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OS FINALS
OS (MOD 1-6)
| Question | Answer |
|---|---|
| this is a program or system software that acts as an interface between the user and the computer hardware and controls the execution of all kinds of programs | operating system (OS) |
| is it possible for the user to use any computer or mobile device without an operating system? | no |
| is it not possible for the user to use any computer or mobile device without an operating system? | yes |
| enumerate the 3 goals of an operating system | (1) EXECUTE user programs and make solving user problems easier, (2) MAKE the computer system convenient to use, (3) USE the computer hardware in an efficient manner |
| enumerate the 4 components of a computer system | Computer Hardware, Application Programs, Users, and Operating System (CAUO) |
| a component of a computer system that is the CPU, memory, I/O devices, which provides basic computing resources for the system | Computer Hardware |
| a component of a computer system that are used to solve the computing problems of the users such as word processors, games and business programs | Application Programs |
| a component of a computer system that are those who utilize a computer or network service trying to solve different problems | Users |
| a component of a computer system that controls and coordinates the use of the hardware among the various application programs for the various users | Operating System |
| what are the two types of software under the Operating System? | System Programs and Application Programs |
| a type of software under the Operating System that is used to control the operation of the computer itself | System Programs |
| a type of software under the Operating System that is used to solve the computing problems of the users | Application Programs |
| enumerate the 9 common services offered by almost all operating systems | User Interface, Program Execution, File System Manipulation, I/O Operations, Communication, Resource Allocation, Error Detection, Job Accounting, and Protection and Security (UPFICRAJP) |
| this common service by all OS refers to the part of an OS, or device that allows a user to enter and receive information | User Interface |
| enumerate the 3 types of UI | Command Line Interface (CLI), Batch-based Interface, and Graphical User Interface (GUI) |
| a type of UI that is a text-only interface that requires the user to type commands, which the computer will then execute | Command Line Interface (CLI) |
| this common service by all OS refers to the capability of an OS to load a program into memory and execute it | Program Execution |
| this common service by all OS refers to when programs need to be read and then written as files and directories | File System Manipulation |
| this common service by all OS also allows users to create and delete files and directories as well as search for a file | File System Manipulation |
| this common service by all OS refers to when a program which is currently executing may require I/O, which may involve a file or an I/O device | I/O Operations |
| who is responsible for reading and/or writing data from I/O devices such as disks, tapes, printers, keyboards, and monitors? | Operating System |
| this common service by all OS refers to when a process needs to swap over information with other processes | Communication |
| processes executing on same/different computer systems can _________ using operating system support | communicate |
| this common service by all OS refers to when the OS manages the different computer resources such as CPU time, memory space, file storage space, I/O devices, etc. and allocates them to different application programs and users | Resource Allocation |
| this common service by all OS refers to how the OS should be able to detect errors within the computer system (CPU, memory, I/O, or user program) and take the appropriate action | Error Detection |
| this common service by all OS refers to when the OS keeps track of time and resources used by various tasks and users, where the information can be used to track resource usage for a particular user or group of users | Job Accounting |
| this common service by all OS refers to any mechanism for controlling access of processes or users to resources defined by the OS, and a defense of the system against internal and external attacks (e.g., denial-of-service, worms, viruses, etc.) | Protection and Security |
| this is the term for any mechanism for controlling access of processes or users to resources defined by the OS | Protection |
| this is the term for a defense of the system against internal and external attacks (e.g., denial-of-service, worms, viruses, etc.) | Security |
| this is the central part of an OS which manages system resources and is always resident in memory | Kernel |
| this acts like a bridge between application and hardware of the computer | Kernel |
| this is the first program that loads after the bootloader | Kernel |
| kernel is the first program that loads after the __________ | bootloader |
| this is a program that loads and starts the boot time tasks and processes of an OS | Bootloader |
| this places the OS of a computer into memory | Bootloader |
| for applications to interact with CPU, memory, and I/O devices, they must go through the __________ | kernel |
| enumerate the 6 types of OS | Batch OS, Time-Sharing OS, Distributed OS, Network OS, Real-Time OS, and Handheld OS (BTDRNH) |
| a type of OS where the user never directly interacts with the computer | Batch OS |
| a type of OS where every user prepares his or her job on an offline device like a punch card and submits it to the computer operator | Batch OS |
| a type of OS where to speed up processing, jobs with similar needs are batched together and run as a group | Batch OS |
| a type of OS where the programmers leave their programs with the operator then the operator sorts the programs with similar requirements into batches | Batch OS |
| a type of OS where the CPU switches jobs so frequently that users can interact with each job while it is running, creating interactive computing | Time-Sharing OS |
| another term for time-sharing OS | Multitasking OS |
| a type of OS where multiple jobs are executed by the CPU by switching between them, but the switches occur so frequently, thus the user can receive an immediate response | Time-Sharing OS |
| in a time-sharing OS, the response time should be less than how many seconds? | 1 second |
| a type of OS where each user has at least one program executing in memory | Time-Sharing OS |
| a type of OS where if there are several jobs ready to run at the same time, CPU scheduling is used | Time-Sharing OS |
| in a time-sharing OS, if there are several jobs ready to run at the same time, what is used? | CPU scheduling |
| a type of OS where if processes don't fit in memory, swapping will take place, which is the process of moving part or all of a process from main memory to disk | Time-Sharing OS |
| in a time-sharing OS, if processes don't fit in memory, what will take place? | swapping |
| a type of OS where examples are Unix, Linux, Multics, and Windows | Time-Sharing OS |
| a type of OS where its systems use multiple central processors to serve multiple real-time applications and multiple users | Distributed OS |
| a type of OS where data processing jobs are distributed among the processors accordingly to which one can perform each job most efficiently | Distributed OS |
| a type of OS where the processors communicate with one another through various communication lines (such as high-speed buses or telephone lines) | Distributed OS |
| a type of OS that are also referred as loosely coupled systems | Distributed OS |
| a type of OS where processors in a distributed system may vary in size and function (these processors are referred as sites, nodes, computers, and so on) | Distributed OS |
| in a distributed OS, ________ in a distributed system may vary in size and function and are referred as sites, nodes, computers, and so on | processors |
| a type of OS where examples are Telecom Network, WWW, Cloud Computing, etc. | Distributed OS |
| a type of OS where it runs on a server and provides the server the capability to manage data, users, groups, security, applications, and other networking functions | Network OS |
| a type of OS where the primary purpose is to allow shared file and printer access among multiple computers in a network, typically a local area network (LAN), a private network or to other networks | Network OS |
| a type of OS where examples are Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X Server, Novell NetWare, and BSD/OS (Berkeley Software Design) | Network OS |
| a type of OS where it is intended to serve real-time systems/applications that process data as it comes in, mostly without buffer delays | Real-Time OS |
| a type of OS where where the time interval required to process and respond to inputs is very small | Real-Time OS |
| in a real-time OS, the time interval required to process and respond to inputs is very ________ | small |
| a type of OS used when there are time requirements that are very strict like missile systems, air traffic control systems, robots, etc. | Real-Time OS |
| a type of OS where examples are LynxOS, OSE, QNX, RTLinux, VxWorks, Windows CE | Real-Time OS |
| a type of OS where it is built exclusively for a mobile device, such as a smartphone, personal digital assistant (PDA), tablet or other embedded OS | Handheld OS |
| a handheld OS is also known as __________ | Mobile OS |
| a type of OS where examples are Android, Symbian, iOS, BlackBerry OS, and Windows Mobile | Handheld OS |
| one or more CPUs, device controllers connect through common _____ providing access to shared _____ | bus; memory |
| concurrent execution of CPUs and devices competing for ________ | memory cycles |
| I/O devices and the CPU can execute ________ | concurrently |
| each _________ is in charge of a particular device type | device controller |
| each device controller has a ________ | local buffer |
| CPU moves data from/to main memory to/from _______ | local buffers |
| this is from the device to local buffer of controller | I/O |
| the device controller informs the CPU that it has finished its operation by causing an ________ | interrupt |
| this is a signal emitted by hardware or software when a process or an event needs immediate attention | interrupt |
| this alerts the processor temporarily to a high priority process requiring interruption of the current working process and then return to its previous task | interrupt |
| an interrupt alerts the processor temporarily to a ________ requiring interruption of the current working process and then return to its previous task | high priority process |
| what are the 2 types of interrupts? | Hardware Interrupts and Software Interrupts |
| this type of interrupt is a signal created and sent to the CPU that is caused by some action taken by a hardware device | Hardware Interrupts |
| this type of interrupt occurs when a key is pressed or when a mouse is moved | Hardware Interrupts |
| this type of interrupt arises due to illegal and erroneous use of an instruction or data | Software Interrupts |
| this type of interrupt often occurs when an application software terminates or when it requests the OS for some service | Software Interrupts |
| this type of interrupt occurs when stack overflow, division by zero, invalid opcode, etc. are thrown | Software Interrupts |
| software interrupts are also called __________ | traps |
| an operating system is _______-driven | interrupt |
| in this process, the OS preserves the state of the CPU by storing registers and the program counter | interrupt handling |
| enumerate the 2 types of interrupt handling | Polling and Vectored Interrupt System |
| this type of interrupt handling is when the OS sends signal to each devices asking if they have a request | Polling |
| this type of interrupt handling is when the requesting device sends an interrupt signal to the OS | Vectored Interrupt System |
| separate segments of code determine what action should be taken for each type of _________ | interrupt |
| this operation allows OS to protect itself and other system components | dual-mode operation |
| what are the 2 modes of operation in dual-mode operation? | User Mode and Kernel Mode |
| this mode of operation in dual-mode operation is where the OS is executed | Kernel Mode |
| this mode of operation in dual-mode operation is where the user programs are executed | User Mode |
| this provides the ability to distinguish when system is running user code or kernel code | the mode bit |
| the mode bit is 1 when the system is running in _______ mode and 0 when the system is running in _______ mode | user; kernel |
| in dual-mode operation, some instructions are designated as _______, which means that they are only executable in kernel mode | privileged |
| in dual-mode operation, this changes the mode to kernel, and returning from it resets it back to user mode | system call |
| in dual-mode operation, this is a way for programs to interact with the OS | system call |
| a computer program makes a _________ when it makes a request to the operating system's kernel | system call |
| what are the 2 processor systems? | Single-Processor System and Multiprocessor System |
| this type of processor system is where a computer system has a main CPU capable of executing a general-purpose instruction set, including instructions from user processes | Single-Processor System |
| this type of processor system is where a computer system has two or more processors in close communication, sharing the computer bus, the clock, memory, and peripheral devices | Multiprocessor System |
| this type of processor system is also known as parallel-system or multicore system | Multiprocessor System |
| this type of processor system first appeared in servers and now in smartphones and tablet computers | Multiprocessor System |
| most systems use a single ________________ (PDAs through mainframes) | general-purpose processor |
| _________ systems are growing in use and importance | multiprocessor |
| these are also known as parallel systems or tightly coupled systems | multiprocessor |
| the advantages to these systems include increased throughput, economy of scale, increased reliability (graceful degradation/fault tolerance) | multiprocessor |
| enumerate the 3 advantages of multiprocessor systems | Increased Throughput, Economy of Scale, and Increased Reliability (graceful degradation/fault tolerance) (IEM) |
| what are the 2 types of multiprocessing? | Asymmetric Multiprocessing and Symmetric Multiprocessing |
| this type of multiprocessing is where each processor is assigned a specific task | Asymmetric Multiprocessing |
| this type of multiprocessing is when a boss processor controls the system and the other processors either look to the boss for instruction or have predefined tasks | Asymmetric Multiprocessing |
| this type of multiprocessing has a boss-worker relationship | Asymmetric Multiprocessing |
| this type of multiprocessing is where each processor performs all tasks within the operating system | Symmetric Multiprocessing |
| this type of multiprocessing is the most commonly used multiprocessing system | Symmetric Multiprocessing |
| this type of multiprocessing is when all processors are peers and there is no boss-worker relationship | Symmetric Multiprocessing |
| the difference between symmetric and asymmetric multiprocessing may result from either the _______ or the ________ | hardware; software |
| this advantage to multiprocessor systems is observed when increasing the number of processor, we expect to get more work done in less time | increased throughput |
| this advantage to multiprocessor systems is observed when it can cost less than equivalent multiple single-processor systems because they share peripherals, mass storage and power supplies | economy of scale |
| this advantage to multiprocessor systems is observed when functions can be distributed properly among several processors; if one processor fails, the other processor can pick-up the task | increased reliability (graceful degradation/fault tolerance) |
| a recent trend in CPU design is to include multiple ________ on a single ________ | computing cores; chip |
| this is the term referring to the trend in CPU design to include multiple computing cores on a single chip | multicore |
| these multiprocessor systems can be more efficient than multiple chips with a single core | multicore |
| a _________ design is a multicore with two cores on the same chip | dual-core |
| in ___________ design, each core has its own register set as well as its own local cache (L1 cache) | dual-core |
| these systems are like multiprocessor systems, but multiple systems working together | clustered systems |
| these systems usually share storage via a storage-area network (SAN) | clustered systems |
| clustered systems usually share storage via a ___________ | storage-area network (SAN) |
| these systems provide a high-availability service which survives failures | clustered systems |
| what are the 2 types of clustering in clustered systems? | Asymmetric Clustering and Symmetric Clustering |
| this type of clustering in clustered systems is where one machine in hot-standby mode (a mode where the secondary machine is running but is not used unless the primary machine fails) | Asymmetric Clustering |
| this type of clustering in clustered systems is where it has multiple nodes running applications, monitoring each other | Symmetric Clustering |
| some _______ are for high-performance computing (HPC) | clusters |
| what are the 2 types of storage used in clusters? | Network-Attached Storage (NAS) and Storage-Area Network (SAN) |
| this type of storage used in clusters is where there is a shared storage over shared network | Network-Attached Storage (NAS) |
| this type of storage used in clusters involves file systems and an easier management | Network-Attached Storage (NAS) |
| this type of storage used in clusters is where there is a shared storage over a dedicated network | Storage-Area Network (SAN) |
| this type of storage used in clusters involves block storage and is fast, but expensive | Storage-Area Network (SAN) |
| the _______ computer is blurring over time | traditional |
| enumerate the 7 computing environments | Traditional Computing, Mobile Computing, Distributed System, Client-Server Computing, Peer-to-Peer (P2P) Computing, Virtualization, and Cloud Computing (TMDPCPV) |
| this is a computing environment involving office environment and home networks | Traditional Computing |
| enumerate the 2 types of traditional computing environments | Office environment and Home networks |
| this is a traditional computing environment where PCs are connected to a network, terminals attached to mainframe or minicomputers providing batch and timesharing | Office environment |
| this is a traditional computing environment where now there are portals allowing networked and remote systems access to same resources | Office environment |
| in an office environment, these allow networked and remote systems access to same resources | portals |
| this is a traditional computing environment where it used to be a single system, then modems | Home networks |
| this is a traditional computing environment where they are now firewalled and networked | Home networks |
| this is a computing environment where it refers to computing on handheld smartphones and tablet computers | Mobile Computing |
| this is a computing environment where it is a collection of physically separate, possibly heterogeneous computer systems that are networked to provide users with access to the various resources that the systems maintain | Distributed System |
| under the distributed system computing environment, this is an OS that provides services across the network | Network OS |
| this is a computing environment where dumb terminals are succeeded by smart PCs | Client-Server Computing |
| this is a computing environment where many systems now servers, respond to requests generated by clients | Client-Server Computing |
| in client-server computing, many systems now ________, respond to requests generated by ________ | servers; clients |
| what are the 2 types of servers in client-server computing? | Compute-Server and File-Server |
| this type of server in client-server computing provides an interface to client to request services (i.e., database) | Compute-Server |
| this type of server in client-server computing provides an interface for clients to store and retrieve files | File-Server |
| this is a computing environment where it does not distinguish clients and servers | Peer-to-Peer (P2P) Computing |
| this is a computing environment where all nodes are considered peers and may each act as client, server, or both | Peer-to-Peer (P2P) Computing |
| in P2P, a _____ must join P2P network to participate by registering its service with _______________ on network, or by broadcasting request for service and respond to requests for service via __________ | node; central lookup service; discovery protocol |
| examples of these computing environment include Napster and BitTorrent | Peer-to-Peer (P2P) Computing |
| this is a computing environment where it is a technology that allows OS to run as applications within other OS | Virtualization |
| this is a computing environment where it is one member of the class software that also includes emulation | Virtualization |
| this is used when the source CPU type is different from the target CPU type | emulation |
| examples of these computing environment include virtual machine and OracleVirtualBox | Virtualization |
| this is a type of computing that delivers computing, storage, and even applications as a service across a network, typically on the Internet | Cloud Computing |
| this is a logical extension of virtualization | Cloud Computing |
| what are the 3 types of cloud computing? | Public Cloud, Private Cloud, and Hybrid Cloud (PPH) |
| this type of cloud is available via the Internet | Public Cloud |
| this type of cloud is run by a company for that company's own use | Private Cloud |
| this type of cloud includes both public and private | Hybrid Cloud |
| enumerate the 3 cloud computing service models | Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS) (IPS) |
| this cloud computing service model involves servers or storage available over the Internet | Infrastructure as a Service (IaaS) |
| this cloud computing service model involves a software stack ready for application use via the Internet | Platform as a Service (PaaS) |
| this cloud computing service model involves one or more applications available via the Internet | Software as a Service (SaaS) |
| this type of cloud computing service model includes Google Apps, Dropbox, Salesforce, Cisco WebEx, Concur, GoToMeeting | Software as a Service (SaaS) |
| this type of cloud computing service model includes AWS Elastic Beanstalk, Windows Azure, Heroku, Force.com, Google App Engine, Apache Stratos, OpenShift | Platform as a Service (PaaS) |
| this type of cloud computing service model includes DigitalOcean, Linode, Rackspace, Amazon Web Services (AWS), Cisco Metapod, Microsoft Azure, Google Compute Engine (GCE) | Infrastructure as a Service (IaaS) |
| these OS are released under a license where the copyright holder allows others to study, change, as well as distribute the software to other people | Open-Source OS |
| this is a counter to the copy protection and Digital Rights Management (DRM) movement | Open-Source OS |
| the Open-Source OS was started by __________ which has "copyleft" GNU Public License (GPL) | Free Software Foundation (FSF) |
| examples of these include GNU (GNU's Not Unix), Linux, and BSD (Berkeley Software Distribution, including core of Mac OS X), and Sun Solaris | Open-Source OS |
| this is a program in execution | process |
| is a program by itself not a process? | yes |
| is a program by itself a process? | no |
| a program is a(n) _______ entity, such as the contents of a file stored on disk | passive |
| a process is a(n) _______ entity, such as a program loaded in memory | active |
| a computer system consists of a collection of processes: OS processes execute _____ code, and user processes execute ______ code | system; user |
| although several processes may be associated with the same program, they are nevertheless considered separate ________ | execution sequences |
| all processes can potentially execute concurrently with the CPU(s) multiplexing among them via _______ | time sharing |
| this is actually a cycle of CPU execution (CPU burst) and I/O wait (I/O burst) | process |
| processes alternate back and forth between these two states, what are they? | CPU burst/wait and I/O burst/wait |
| this begins with a CPU burst, followed by an I/O burst, followed by another CPU burst, and so on until the process completes | process execution |
| in process execution, eventually the last CPU burst will end with a ____________ to terminate execution | system request |
| we write our computer programs in a ____ file, and when we execute this program, it becomes a ____ which performs all the tasks mentioned in the program | text; process |
| when a program is loaded into the memory and it becomes a process, it can be divided into four sections, what are they? | Stack, Heap, Data, Text (SHDT, also arranged in this order in main memory) |
| this section in the process architecture contains the temporary data such as method/function parameters, return address and local variables | stack |
| this section in the process architecture contains the dynamically allocated memory to a process during its run time | heap |
| this section in the process architecture includes the current activity represented by the value of program counter and the contents of the processor's registers | text |
| this section in the process architecture contains the global and static variables | data |
| as a process executes, it changes _____ | state |
| the _______ activity of a process party defines its state | current |
| enumerate the 5 states of a process | new, ready, running, waiting, terminated (NRRWT) |
| this state of a process is the initial state when the process is being created | new |
| this state of a process is the state when the CPU is executing its instructions | running |
| this state of a process is the state when the process is waiting for some event to occur, such as an I/O completion or reception of a signal | waiting |
| this state of a process is the state when the process is waiting for the OS to assign a processor to it | ready |
| this state of a process is the state when the process has finished execution | terminated |
| a(n) _____ switches from a running state to a ready state to allow another process to run | interrupt |
| a(n) _____ switches from a ready state to a running state to allow the process to run | scheduler dispatch |
| when a process is _______, we change from the new state to the ready state | admitted |
| after ___________, we change from the waiting state to the ready state | I/O or event completion |
| after ___________, we change from the running state to the waiting state | I/O or event wait |
| after ___________, we change from the running state to the terminated state | exiting |
| each process is represented in the OS by a _______ | process control block (PCB) |
| a PCB is also called a _______ | task control block |
| this is a data block or record containing many pieces of the information with a specific process | process control block (PCB) |
| enumerate the 7 pieces of information in a PCB | process state, program counter, CPU registers, CPU scheduling information, memory-management information, accounting information, I/O status information (PPCCMAI) |
| this piece of information in a PCB contains the current state of the process; the state may be new, ready, running, waiting, or halted | process state |
| this piece of information in a PCB indicates the address of the next instruction to be executed for this process | program counter |
| this piece of information in a PCB include accumulators, index registers, stack pointers, and general-purpose registers | CPU registers |
| along with the program counter, this piece of information in a PCB must be saved when an interrupt occurs, so that the process can be resumed correctly afterward | CPU registers |
| this piece of information in a PCB includes a process priority, pointers to scheduling queues, and any other scheduling parameters | CPU scheduling information |
| this piece of information in a PCB includes limit registers or page tables | memory-management information |
| this piece of information in a PCB includes the amount of CPU and real time used, time limits, account numbers, job or process numbers, and so on | accounting information |
| this piece of information in a PCB includes outstanding I/O requests, I/O devices (such as disks) allocated to this process, a list of open files, and so on | I/O status information |
| this simply serves as the repository for any information that may vary from process to process | process control block (PCB) |
| what is a diagram that shows an example of the CPU being switched from one process to another? | context switch diagram |
| the processes in the system can execute _________; that is, many processes may be multitasked on a CPU | concurrently |
| a process may create several new processes, via a _______ system call, during the course of execution | create-process |
| each of the new processes created in a _______ system call may also create new processes, and so on | create-process |
| the creating process is the _______ process, whereas the new processes are the _______ of that process | parent; children |
| when a process creates a sub-process, the sub-process may be able to obtain its resources from these two sources | directly from the OS, or a subset of the resources of the parent process |
| restricting a _______ process to a subset of the _______'s resources prevents it from overloading the system by creating too many processes | child; parent |
| when a process creates a new process, what are the 2 common implementations that exist in terms of execution? | (1) the parent continues to execute concurrently with its children, (2) the parent waits until all its children have terminated |
| a process terminates when it finishes its last statement and asks the OS to delete it by using a _______ system call | exit |
| a parent may terminate the execution of one of its children for these 3 reasons | (1) the child has exceeded its usage of some of the resources it has been allocated, (2) the task assigned to the child is no longer required, and (3) the parent is exiting, and the OS does not allow a child to continue if its parent terminates |
| in such systems where the children of a process dies when the parent dies, this phenomenon is referred to as __________ | cascading termination |
| the concurrent processes executing in the OS may either be _________ processes or _________ processes | independent; cooperating |
| a process is __________ if it cannot affect or be affected by the other processes | independent |
| clearly, any process that does not share any data (temporary or persistent) with any other process is __________ | independent |
| enumerate the 3 characteristics of an independent process | (1) DETERMINISTIC; the result depends solely on the input state, (2) REPRODUCIBLE; the result will always be the same for the same input, and (3) its execution can be STOPPED, and restarted without causing ill effects (DRS) |
| when the result of an independent process depends solely on the input state, its execution is said to be _________ | deterministic |
| when the result of an independent process will always be the same for the same input, its execution is said to be _________ | reproducible |
| a process is __________ if it can affect or be affected by the other processes | cooperating |
| clearly, any process that shares data with other processes is a __________ process | cooperating |
| enumerate the 2 characteristics of a cooperating process | (1) the results cannot be PREDICTED in advance; it depends on relative execution sequence, and (2) the result is NONDETERMINISTIC since it will not always be the same for the same input (PN) |
| when the result of a cooperating process will not always be the same for the same input, its execution is said to be _________ | non-deterministic |
| concurrent execution of __________ processes requires mechanisms that allow processes to communicate with one another and to synchronize their actions | cooperating |
| the objective of ____________ is to have some process running at all times, to maximize CPU utilization | multiprogramming |
| this increases throughput, which is the amount of work the system accomplishes in a given time interval | multiprogramming |
| this is the amount of work the system accomplishes in a given time interval (e.g., 17 processes per minute) | throughput |
| the idea of ___________ is if one process is in the waiting state, then another process which is in the ready state goes to the running state | multiprogramming |
| as processes enter the system, they are put into a __________, which consists of all processes in the system | job queue |
| the processes that are residing in main memory and are ready and waiting to execute are kept on another queue which is the __________ | ready queue |
| a ______ migrates between the various scheduling queues throughout its lifetime | process |
| the selection process (when the OS must select processes from various scheduling queues) is the responsibility of the appropriate ____________ | scheduler |
| enumerate the 3 types of schedulers | long-term scheduler (job scheduler), short-term scheduler (CPU scheduler), and medium-term scheduler (LSM) |
| this type of scheduler selects processes from the secondary storage (disk) and loads them into main memory for execution | long-term scheduler or job scheduler |
| this type of scheduler executes much less frequently compared to the other two schedulers | long-term scheduler or job scheduler |
| in this type of scheduler, there may be minutes between the creation of new processes in the system | long-term scheduler or job scheduler |
| this type of scheduler controls the degree of multiprogramming (the number of processes in memory) | long-term scheduler or job scheduler |
| in this type of scheduler, because of the longer interval between executions, it can afford to take more time to select a process for execution | long-term scheduler or job scheduler |
| this type of scheduler selects process from among the processes that are ready to execute, and allocates the CPU to one of them | short-term scheduler or CPU scheduler |
| this type of scheduler must select a new process for the CPU frequently (milliseconds) | short-term scheduler or CPU scheduler |
| in this type of scheduler, a process may execute for only a few milliseconds before waiting for an I/O request | short-term scheduler or CPU scheduler |
| this type of scheduler is also known as the dispatcher | short-term scheduler or CPU scheduler |
| in this type of scheduler, because of the brief time between executions, it must be very fast | short-term scheduler or CPU scheduler |
| this type of scheduler removes (swaps out) certain processes from memory to lessen the degree of multiprogramming (particularly when thrashing occurs) | medium-term scheduler |
| in this type of scheduler, at some later time, the process can be reintroduced into memory and its execution can be continued where it left off | medium-term scheduler |
| the scheme where the process can be reintroduced into memory and its execution can be continued where it left off is called __________ | swapping |
| this is the task of switching the CPU to another process which requires some time to save the state of the old process and loading the saved state for the new process | context switch |
| __________ time is pure overhead, because the system does no useful work while switching and should therefore be minimized | context switch |
| whenever the CPU becomes ___, the OS (particularly the CPU scheduler) must select another process from the ready queue | idle |
| enumerate the 4 circumstances where CPU scheduling decisions may take place | (1) when a process switches from the RUNNING state to the WAITING state, (2) when a process switches from the RUNNING state to the READY state, (3) when a process switches from the WAITING state to the READY state, and (4) when a process terminates |
| in I/O request, invocation of wait for the termination of one of the child processes, the process switches from what state to what state? | RUNNING to WAITING |
| when an interrupt occurs, the process switches from what state to what state? | RUNNING to READY |
| in completion of I/O, the process switches from what state to what state? | WAITING to READY |
| in termination, the process switches from what state to what state? | RUNNING to TERMINATED |
| for these two circumstances out of 4, there is no choice in terms of scheduling; a new process (if one exists in the ready queue) must be selected for execution | when a process switches from RUNNING to WAITING and when the process terminates |
| for these two circumstances out of 4, the OS has to select another process for execution | when a process switches from RUNNING to READY and when a process switches from WAITING to READY |
| when scheduling takes place only under the circumstances (1) when a process switches from RUNNING to WAITING and (4) when a process terminates, this is called __________ | nonpreemptive scheduling |
| when scheduling takes place also under the circumstances (2) when a process switches from RUNNING to READY and (3) when a process switches from WAITING to READY, this is called __________ | preemptive scheduling |
| what are the 2 types of scheduling algorithms? | nonpreemptive scheduling and preemptive scheduling |
| this type of scheduling algorithm is when once the CPU has been allocated to a process, the process keeps the CPU until it releases the CPU either by terminating or switching states | nonpreemptive scheduling |
| in this type of scheduling algorithm, no process is interrupted until it is completed, and after that processor switches to another process | nonpreemptive scheduling |
| this type of scheduling algorithm works by dividing time slots of CPU to a given process; the time slot given might be able to complete the whole process or might not be able to it | preemptive scheduling |
| in this type of scheduling algorithm, when the burst time of the process is greater than CPU cycle, it is placed back into the ready queue and will execute in the next chance | preemptive scheduling |
| this type of scheduling algorithm is used when the process switches to a ready state again | preemptive scheduling |
| different ____________ algorithms have different properties and may favour one class of processes over another | CPU-scheduling |
| many criteria have been suggested for comparing CPU-scheduling algorithms, what are these 5 characteristics used in determination of the best algorithm? | CPU utilization, throughput, turnaround time, waiting time, response time (CTTWR) |
| this characteristic used in comparing CPU-scheduling algorithms measures how busy is the CPU | CPU utilization |
| this characteristic used in comparing CPU-scheduling algorithms may range from 0 to 100 percent | CPU utilization |
| in this characteristic used in comparing CPU-scheduling algorithms, it should range from 40 percent (lightly loaded) to 90 percent (heavily loaded) in a real system | CPU utilization |
| this characteristic used in comparing CPU-scheduling algorithms is the amount of work completed in a unit of time | throughput |
| this characteristic used in comparing CPU-scheduling algorithms is the processes executed to number of jobs completed in a unit of time | throughput |
| in this characteristic used in comparing CPU-scheduling algorithms, the scheduling algorithm must look to maximize the number of jobs processed per time unit | throughput |
| this characteristic used in comparing CPU-scheduling algorithms measures how long it takes to execute a process | turnaround time |
| this characteristic used in comparing CPU-scheduling algorithms is the interval from the time of submission to the time of completion of a process | turnaround time |
| this characteristic used in comparing CPU-scheduling algorithms is the sum of the periods spent waiting to get into memory, waiting in the ready queue, executing on the CPU, and doing I/O | turnaround time |
| this characteristic used in comparing CPU-scheduling algorithms is the time a job waits for resource allocation when several jobs are competing in a multiprogramming system | waiting time |
| this characteristic used in comparing CPU-scheduling algorithms is the total amount of time a process spends waiting in the ready queue | waiting time |
| this characteristic used in comparing CPU-scheduling algorithms is the time from the submission of a request until the system makes the first response | response time |
| this characteristic used in comparing CPU-scheduling algorithms is the amount of time it takes to start responding but not the time it takes to output that response | response time |
| a good CPU-scheduling algorithm _________ CPU utilization and throughput and _________ turnaround time, waiting time, and response time | maximizes; minimizes |
| in most cases for CPU-scheduling algorithms, the ______ measure is optimized; however, in some cases, it is desired to optimize the _______ or _______ instead | average; minimum or maximum |
| in CPU-scheduling algorithms, to guarantee that all users get good service, it may be better to minimize the maximum ___________ | response time |
| for interactive (time-sharing) systems, some analysts suggest that minimizing the _________ in the response time is more important than minimizing the average response time | variance |
| which is more desirable: (1) a system with a reasonable and predictable response may be considered vs. (2) a system that is faster on the average, but is highly variable | (1) a system with a reasonable and predictable response |
| enumerate the 3 non-preemptive scheduling algorithms | first-come, first-served (FCFS), shortest-job-first (SJF), and non-preemptive priority scheduling (FPS) |
| enumerate the 3 preemptive scheduling algorithms | round-robin (RR), shortest-remaining-time-first (SRTF), and preemptive priority scheduling (RSP) |
| this CPU-scheduling algorithm is the simplest scheduling algorithm | first-come, first-served (FCFS) |
| this CPU-scheduling algorithm is when the process that requests the CPU first gets the CPU first | first-come, first-served (FCFS) |
| the _____ chart is a useful way of illustrating CPU scheduling algorithms | Gantt |
| what is the formula of waiting time? | waiting time = start time - arrival time |
| what is the formula of turnaround time? | turnaround time = completion time - arrival time |
| this CPU-scheduling algorithm associates with each process the length of the latter's next CPU burst | shortest-job-first (SJF) |
| in this CPU-scheduling algorithm, when the CPU is available, it is assigned to the process that has the smallest next CPU burst | shortest-job-first (SJF) |
| in this CPU-scheduling algorithm, if two processes have the same length next CPU burst, FCFS scheduling is used to break the tie | shortest-job-first (SJF) |
| in SJF scheduling, if two processes have the same length next CPU burst, what scheduling is used to break the tie? | FCFS scheduling |
| this CPU-scheduling algorithm is one of the most common scheduling algorithms in batch systems | priority scheduling (non-preemptive) |
| in this CPU-scheduling algorithm, each process is assigned a priority, and the process with highest priority is to be executed first and so on | priority scheduling (non-preemptive) |
| in this CPU-scheduling algorithm, processes with the same priority are executed on a first-come, first-served basis | priority scheduling (non-preemptive) |
| in priority scheduling, processes with the same priority are executed on a _________ basis | first-come, first-served |
| in this CPU-scheduling algorithm, priority can be decided based on memory requirements, time requirements or any other resource requirement | priority scheduling (non-preemptive) |
| this CPU-scheduling algorithm is similar to SJF, but preemption is added | shortest-remaining-time-first (SRTF) |
| in this CPU-scheduling algorithm, a new process arriving may have a shorter next CPU burst than what is left of the currently executing process | shortest-remaining-time-first (SRTF) |
| this CPU-scheduling algorithm will preempt the currently executing process if its next CPU burst is shorter than the remaining time of the currently executing process | shortest-remaining-time-first (SRTF) |
| preemptive SJF scheduling is sometimes called __________ | shortest-remaining-time-first (SRTF) |
| in this CPU-scheduling algorithm, when a process arrives at the ready queue, its priority is immediately compared with the priority of the currently running process | preemptive priority scheduling |
| this CPU-scheduling algorithm will preempt the CPU if the priority of the newly arrived process is higher than the priority of the currently running process | preemptive priority scheduling |
| this CPU-scheduling algorithm is specifically for time-sharing systems | round-robin (RR) |
| a small unit of time, called a ________, is defined | time quantum (time slice) |
| this CPU-scheduling algorithm, the ready queue is treated as a circular queue | round-robin (RR) |
| in round-robin, the ready queue is treated as a ________ | circular queue |
| in this CPU-scheduling algorithm, the CPU scheduler goes around the ready queue, allocating the CPU to each process for a time interval of up to 1 time quantum | round-robin (RR) |
| the performance of this CPU-scheduling algorithm depends heavily on the size of the time quantum | round-robin (RR) |
| in this CPU-scheduling algorithm, if the time quantum is too large, it degenerates into the FCFS policy | round-robin (RR) |
| in round-robin, if the time quantum is too large, it degenerates into the ________ policy | FCFS |
| in this CPU-scheduling algorithm, if the time quantum is too small, then the effect of the context-switch time becomes a significant overhead | round-robin (RR) |
| in round-robin, if the time quantum is too small, then the effect of the ________ becomes a significant overhead | context-switch time |
| in round-robin, as a general rule, __ percent of the CPU burst should be shorter than the time quantum | 80 |
| in this CPU-scheduling algorithm, 80 percent of the CPU burst should be shorter than the time quantum | round-robin (RR) |
| this is the functionality of an OS which handles/manages primary memory and moves processes back and forth between main memory and disk during execution | memory management |
| the OS keeps track of each memory location, regardless of either it is ______ to some process or it is free | allocated |
| the OS checks how much ______ is to be allocated to processes | memory |
| the OS decides which process will get memory at what ____ | time |
| the OS tracks whenever some memory gets _____ or _____ and correspondingly updates the status | freed; unallocated |
| this is the process of mapping from one address space to another address space | address binding |
| usually, a program resides on a disk as a __________ | binary executable file |
| the _____ must be brought into main memory before the CPU can execute it | program |
| depending on the memory management scheme, the process of executing programs may be moved between ____ and ____ during its execution | disk; memory |
| the collection of processes on the disk that are waiting to be brought into memory for execution forms the ______ or ______ | job queue / input queue |
| enumerate the 3 types of address binding | (1) COMPILE-TIME, (2) LOAD-TIME, (3) EXECUTION-TIME |
| this is when if you know that during compile time where process will reside in memory, absolute address is generated | compile-time address binding |
| an example of this type of address binding is when physical address is embedded to the executable of the program during compilation | compile-time address binding |
| in this type of address binding, loading the executable as a process in memory is very fast | compile-time address binding |
| in this type of address binding, if the generated address space is preoccupied by other process, then the program crashes and it becomes necessary to recompile the program | compile-time address binding |
| this is when if it is not known at the compile time where process will reside, then a relocatable address is generated | load-time address binding |
| compile-time address binding generates ____ address | absolute |
| load-time address binding generates ____ address | relocatable |
| the _____ is the one that translates the relocatable address to absolute address | loader |
| the base address of the process in memory is added to all _______ addresses by the loader to generate the absolute address | logical |
| this is when the base address of the process is added to all logical addresses to generate the absolute address | load-time address binding |
| in this type of address binding, if the base address of the process changes then we need to reload the process again | load-time address binding |
| this is the type of address binding where the instructions are in memory and are being processed by the CPU | execution-time address binding |
| in this type of address binding, additional memory may be allocated and/or deallocated at this time | execution-time address binding |
| this type of address binding is used if process can be moved from one memory to another during execution | execution-time address binding |
| this is the linking that is done during load or run time | dynamic linking |
| compaction is done only in what type of address binding? | execution-time address binding |
| to obtain better memory-space utilization, ____ loading is used | dynamic |
| with _______, a routine is not loaded from disk until it is called | dynamic loading |
| whenever a routine is called in dynamic loading, the ___________ is called to load the desired routine into memory and to update the program's address tables | relocatable linking loader |
| this is a method that helps OS to collect and merge various modules of code and data into a single executable file | linking |
| OS can link system-level libraries into a program that combines the libraries at ____ time | load |
| in _______ method, libraries are linked at execution time, so program code size can remain small | dynamic linking |
| in dynamic linking method, libraries are linked at ______ time | execution |
| this is an address generated by the CPU | logical address |
| this is an address seen by the memory unit | physical address |
| these two address binding schemes result in an environment where the logical address and the physical address are the same | compile-time and load-time address binding |
| in this type of address binding, the logical and physical addresses differ | execution-time address binding |
| the run-time mapping from logical to physical addresses is done by the _______, a hardware device | memory management unit (MMU) |
| when mapping from logical to physical address, the base register is now the ______ register | relocation |
| when mapping from logical to physical address, the value in the relocation register is _____ to every address generated by the user process at the time it is sent to memory | added |
| this is the process of reserving a partial or complete portion of computer memory for the execution of programs/processes | memory allocation |
| main memory has two partitions, what are they and what resides in each? | (1) OS resides in LOW memory, (2) user processes are held in HIGH memory |
| enumerate the 4 memory allocation techniques | (1) SINGLE PARTITION ALLOCATION, (2) MULTIPLE PARTITION ALLOCATION, (3) PAGING, (4) SEGMENTATION |
| enumerate the 3 types of multiple partition allocation | (1) FIXED, (2) VARIABLE/DYNAMIC, (3) RELOCATABLE VARIABLE/DYNAMIC |
| this is a memory allocation technique that set aside some memory for the OS and user program gets the rest | single partition allocation |
| this is a memory allocation technique that use MMU to translate addresses by simple addition | single partition allocation |
| this is a memory allocation technique that does not support multiprogramming | single partition allocation |
| this is a memory allocation technique that supports multiprogramming | multiple partition allocation |
| this is a memory allocation technique that is the oldest and simplest technique used to put more than one processes in memory | multiple fixed partition allocation |
| in this partitioning technique, number of partitions (non-overlapping) in RAM are fixed but size of each partition may vary | multiple fixed partition allocation |
| in this partitioning technique, the operating system divides main memory into a number of partitions wherein each partition may contain only one process | multiple fixed partition allocation |
| in fixed partitions, the ___________ is bounded by the number of partitions | degree of multiprogramming |
| in fixed partitions, when a partition is free, the OS selects a process from the _______ and loads it into the free partition | job/input queue |
| in fixed partitions, the OS places jobs/processes entering the memory in a job queue on a ________ manner (such as FCFS) | predetermined |
| enumerate the 2 ways we can allocate jobs to partitions | (1) FIRST-FIT, (2) BEST-FIT |
| in this way of allocating jobs to partitions, the first job claims the first available memory with space more than or equal to its size | FIRST-FIT ALLOCATION |
| in this way of allocating jobs to partitions, the OS doesn't search for appropriate partition but just allocate the job to the nearest memory partition available with sufficient size | FIRST-FIT ALLOCATION |
| in this way of allocating jobs to partitions, the OS keeps the free/busy list in order by size--smallest to largest | BEST-FIT ALLOCATION |
| in this way of allocating jobs to partitions, the OS first searches the whole memory according to the size of the given job and allocates it to the closest-fitting free partition in the memory | BEST-FIT ALLOCATION |
| one flaw of the _______ algorithm is that it forces other jobs (particularly those at the latter part of the queue) to wait even though there are some free partitions | FIRST-FIT |
| this algorithm allows small jobs to use a much larger memory partition if it is the only partition left, but still wastes some memory space | BEST-FIT |
| what if a process in a fixed partition requests for more memory? | (1) kill it, (2) return "out of memory" message, (3) reswap to bigger partition (dynamic relocation) |
| this happens as processes are loaded and removed from memory, and the free memory space is broken into little pieces | fragmentation |
| this happens when processes cannot be allocated to memory blocks considering their small size and memory blocks remains unused | fragmentation |
| what are the two types of fragmentation? | (1) INTERNAL, (2) EXTERNAL |
| this type of fragmentation occurs when a partition is too big for a process | internal |
| this type of fragmentation is the difference between the partition size and the process size | internal |
| this type of fragmentation occurs when a partition is available, but is too small for any waiting job | external |
| this is the total process size inside partitions divided by the total memory available | memory utilization (%) |
| this is a memory allocation technique where the system allows the region sizes to vary dynamically | multiple variable partition technique (MVT) |
| this is a memory allocation technique where it is possible to have a variable number of tasks in memory simultaneously | multiple variable partition technique (MVT) |
| in MVT, initially the OS views memory as one large block of available memory called a ____ | hole |
| in MVT, when a job arrives and needs memory, the system searches for a hole ____ enough for the job | large |
| this is a memory allocation technique where if a hole in memory exists, the OS allocates only as much as is needed, keeping the rest available | multiple variable partition technique (MVT) |
| enumerate the 3 types of variable partition allocation | (1) FIRST-FIT, (2) BEST-FIT, (3) WORST-FIT |
| in this way of allocating jobs to variable partitions, the OS allocates the job to the first hole that is large enough | FIRST-FIT |
| in this way of allocating jobs to variable partitions, the OS allocates the job to the smallest hole that is large enough | BEST-FIT |
| in this way of allocating jobs to variable partitions, the OS allocates the job to the largest hole | WORST-FIT |
| this algorithm for variable partition allocation is generally faster | FIRST-FIT |
| this algorithm for variable partition allocation is where empty spaces tend to migrate toward higher memory | FIRST-FIT |
| this algorithm for variable partition allocation produces the smallest leftover hole | BEST-FIT |
| this algorithm for variable partition allocation may leave many holes that are too small to be useful | BEST-FIT |
| this algorithm for variable partition allocation produces the largest leftover hole | WORST-FIT |
| this algorithm for variable partition allocation tends to scatter the unused portions over non-contiguous areas of memory | WORST-FIT |
| in MVT, if the hole is too ____ for the job, the system splits it into two: one for the job, the other for the remaining set of holes | large |
| in MVT, when a job terminates, it releases its ________ | block of memory |
| in MVT, if the new hole is _______ to other holes, the system merges these holes to form one larger hole | adjacent |
| in MVT, the process of two adjacent holes merging into one hole is called what? | coalescing |
| this kind of fragmentation does not exist in MVT | internal |
| this kind of fragmentation still exists in MVT | external |
| in MVT, it is possible to have several holes with sizes too ____ for any job | small |
| in MVT, external fragmentation can be resolved using what? | compaction |
| this is the process of shuffling the memory contents to place all free memory together in one large block | compaction |
| this is a memory allocation technique where compaction is possible | multiple relocatable variable partition technique (MRVT) |
| this is a memory allocation technique where the OS can move processes around in memory | multiple relocatable variable partition technique (MRVT) |
| note that compaction is possible only if relocation is _____, and is done at ____ time | dynamic; execution |
| this is a memory allocation technique that still suffers from external fragmentation when available memory is not contiguous | multiple variable partition technique (MVT) |
| aside from compaction (MRVT), this memory allocation technique can minimize the external fragmentation of MVT | paging |
| this is a memory allocation technique that permits a program's memory to be non-contiguous, thus allowing the OS to allocate a program physical memory whenever possible | paging |
| this is a memory management technique for controlling how a computer or virtual machine's (VM's) memory resources are shared | memory paging |
| in paging, this non-physical memory, which is called _______, is actually a section of a hard disk that's set up to emulate the computer's RAM | virtual memory |
| in paging, the portion of the hard disk that acts as physical memory is called a ______ | page file |
| in paging, the OS divides main memory into fixed-sized blocks called ______ | frames |
| in paging, the system breaks a process into blocks called ____ | pages |
| the size of a memory frame is ____ to the size of a process page | equal |
| in paging, the pages of a process may reside in _____ frames in memory | different |
| in paging, using the ______, the OS translates this logical address into a physical address | page table |
| in paging, a logical address has two parts: ____ and ____ | (1) PAGE NUMBER, (2) PAGE OFFSET |
| in paging, this part of a logical address indicates what page the word resides in | page number (p) |
| in paging, this part of a logical address indicates the displacement within the page | page offset (d) |
| in paging, this part of a logical address selects the word within the page | page offset (d) |
| in paging, this is used as an index into the page table | page number (p) |
| this contains the base address of each page in physical memory | page table |
| this ______ is combined with the ______ to define the physical memory address sent to the memory unit | base address; page offset |
| the page size (like the frame size) is defined by the _____ | hardware |
| the size of a page is typically a power of __ varying between ___ bytes and __ MB per page, depending on architecture | 2; 512; 16 |
| if the size of a logical address space is 2^m and the page size is 2^n addressing units, then the high-order ____ bits of a logical address designate the page number | m-n |
| if the size of a logical address space is 2^m and the page sie is 2^n addressing units, then the n lower-order bits designate the _____ | page offset |
| if the memory size is 32 bytes, the process size is 16 bytes, and page/frame size is 4 bytes, how many MM frames are there? | 8 frames |
| if the memory size is 32 bytes, the process size is 16 bytes, and page/frame size is 4 bytes, how many pages are there? | 4 pages |
| if the memory size is 32 bytes, the process size is 16 bytes, and page/frame size is 4 bytes, how many bits are needed for the page number? | 2 bits |
| if the memory size is 32 bytes, the process size is 16 bytes, and page/frame size is 2 bytes, how many bits are needed for the page offset? | 1 bit |
| if the memory size is 32 bytes, the process size is 16 bytes, and page/frame size is 8 bytes, how many bits are needed for the logical address? | 4 bits (1 bit for page number, 3 bits for page offset) |
| what's the formula for physical address? | frame no. * page size + offset |
| in paging, there is no _____ fragmentation | external |
| in this memory allocation technique, there is no external fragmentation because the OS can allocate any free frame to a process that needs it | paging |
| in paging, there is still _____ fragmentation | internal |
| why is there still internal fragmentation in paging? | because the last page may not completely fill up a frame |
| if the page size is 2048 bytes, and the process size is 72,766 bytes, how many pages are needed? | 36 pages (35 full pages, and 1 page with 1086 bytes) |
| if the page size is 2048 bytes, and the process size is 72,766 bytes, how much is the internal fragmentation? | 962 bytes (2048 - 1086) |
| this is a memory allocation technique in which each job is divided into several segments of different sizes, one for each module that contains pieces that perform related functions | segmentation |
| when a process is to be executed, its corresponding segmentation are loaded into ________ memory though every segment is loaded into a _____ block of available memory | non-contiguous; contiguous |
| this works very similar to paging except segments are of variable-length whereas in paging pages are of fixed size | segmentation |
| segmentation memory management works very similar to paging but here segments are of ______ length | variable |
| in segmentation, this contains the program's main function, utility functions, data structures, and so on | program segment |
| this is a collection of segments where each segment has a name and length | logical address space |
| in segmentation, these specify the name of the segment or its base address and the offset within that segment | addresses |
| in segmentation, the OS maintains a _______ for every process | segment map table |
| for each segment, the table stores the starting address of the segment called ____ and the length of the segment called ____ | base; limit |
| a reference to a byte outside a segment's limit would result in a ____ to the OS | trap |
| the various memory management strategies that are used in computer systems have the same goal: to keep many processes in memory simultaneously to allow ________ | multiprogramming |
| memory management strategies tend to require the entire process to be in ____ before the process can execute | memory |
| this is a technique that allows the execution of processes that may not be completely in memory | virtual memory |
| one major advantage of this scheme is that programs can be larger than physical memory | virtual memory |
| this abstracts main memory into an extremely large, uniform array of storage, separating logical memory as viewed by the user from physical memory | virtual memory |
| this technique frees programmers from the concerns of memory-storage limitations | virtual memory |
| with this, users would be able to write programs for an extremely large virtual-address space | virtual memory |
| with virtual memory, users would be able to write programs for an extremely large ______ | virtual-address space |
| with this, because each user program could take less physical memory, more programs could run at the same time | virtual memory |
| in this, less I/O would be needed to load or swap each user program into memory, so each program would run faster | virtual memory |
| in virtual memory, less ______ would be needed to load or swap each user program into memory, so each program would run faster | I/O |
| this is the separation of user logical memory from physical memory | virtual memory |
| this system is similar to a paging system with swapping | demand-paging system |
| in this system, instead of swapping the entire procses into memory, the OS (particularly the pager) swaps only the necessary pages into memory | demand-paging system |
| demand-paging is also called what? | lazy swapping |
| in demand-paging, there is an additional bit in the page table which is the ___________ bit | valid-invalid |
| in this system, unlike normal paging, the page table entry has a valid-invalid bit | demand-paging system |
| this bit is set to valid to indicate that a corresponding page is in memory | valid-invalid |
| the valid-invalid bit is set to ____ to indicate that a corresponding page is in memory | valid |
| the valid-invalid bit is set to ____ to indicate that a corresponding page is not in memory, but in secondary storage | invalid |
| in demand-paging, if a process tries to use a page that is not in physical memory, then a _______ will occur | page fault |
| in this, if a process tries to use a page that is not in physical memory, then a page fault will occur | demand-paging |
| this will cause a trap to the operating system indicating an invalid address error | page fault |
| in the extreme case, the system could start executing a process with ___ pages in memory | zero / no |
| in demand-paging, the process would immediately fault for the page with the ____ instruction | first |
| in this, the process would immediately fault for the page with the first instruction | demand-paging |
| what does the OS do when a page fault occurs? | brings in the page from secondary storage to physical memory |
| faulting as necessary until every page that it needed was actually in memory is called ____ demand-paging | pure |
| ____ demand-paging says to never bring a page into memory until it is required | pure |
| in demand-paging, the principle of __________ ensures that programs do not access a new page of memory with each instruction execution | locality of reference |
| the effectiveness of the demand paging is based on a property of computer programs called the ____________ | locality of reference |
| analysis of programs shows that most of their execution time is spent on ____ in which many instructions are executed repeatedly | routines |
| it is important to keep the page-fault rate low in a demand-paging system to prevent __________ | thrashing |
| this happens when a system spends most of its time swapping pages in and out | thrashing |
| it is important to keep the page-fault rate ___ in a demand-paging system | low |
| it is important to keep the ________ rate low in a demand-paging system | page-fault |
| when page-fault rate is not low, the __________ increases, slowing down process execution dramatically | effective access time |
| if there is a need to transfer a page from disk to memory but there is no memory space available (in short, memory is ________) | over-allocated |
| users should not be ____ their processes are running on a paged system | aware |
| paging should be logically __________ to the user | transparent |
| in this scheme, the OS removes or replaces one of the existing pages in memory to give way for the incoming page | page replacement |
| this algorithm is necessary to select which among the pages in memory should be replaced | page-replacement algorithm |
| in this, if no frame is free, the system finds one that is currently being used and frees it | page-replacement |
| _______ a frame means transferring its contents to the disk and changing the page table (and all other tables) to indicate that the page is no longer in memory | freeing |
| enumerate the 7 steps of page-replacement | (1) find location of page on disk, (2) find free frame, (3) exists? use it, (4) else, use PR-A to select victim, (5) write victim to disk & change tables, (6) read new page to free frame & change tables, (7) restart process |
| in page replacement, if no frames are free, how many page transfers are required? | two (one out and one in) |
| to reduce the overhead of two page transfers per page fault, a _____ or _____ is necessary for each page or frame | modify bit / dirty bit |
| this is set whenever any word or byte is written into, indicating that the page has been modified | modify bit / dirty bit |
| the modify bit is set to 0 when the page is not ______ | modified |
| the modify bit is set to 1 when the page is ______ | modified |
| it is no longer necessary to swap out pages whose modify bit is ___ | zero |
| enumerate the 2 major problems in the implementation of demand-paging | (1) FRAME ALLOCATION, (2) PAGE REPLACEMENT |
| this major problem in demand-paging is concerned with how many frames the OS will allocate to a process, particularly if there are multiple processes | frame allocation |
| this major problem in demand-paging is concerned with how the OS will select which page will be removed to give way for incoming pages | page replacement |
| enumerate the 3 major page-replacement algorithms | (1) FIFO, (2) OPTIMAL, (3) LRU |
| these are the techniques using which an OS decides which memory pages to swap out, write to disk when a page of memory needs to be allocated | page-replacement algorithms |
| a good ____________ algorithm will result in a low page-fault rate | page-replacement |
| a good page-replacement algorithm will result in a low ______ rate | page-fault |
| a PR algorithm is evaluated by running it on a particular string of _______ and computing the number of page faults | memory references |
| a string of memory references is called a _______ | (page) reference string |
| this is the simplest page-replacement algorithm | FIRST-IN FIRST-OUT (FIFO) |
| in this PR algorithm, the OS keeps track of all pages in memory in a queue, with the most recent page at the end | FIFO |
| in FIFO, the OS removes the page at the ______ of the queue | front/head |
| in this PR algorithm, when a page must be replaced, the oldest page is chosen | FIFO |
| in FIFO, the _____ page is chosen when a page must be replaced | oldest |
| in FIFO, it is not strictly necessary to record the ___ when a page is brought in | time |
| in FIFO, when a page is brought into memory, it is inserted at the ___ of the queue | end/tail |
| the performance of this PR algorithm is not good | FIFO |
| this PR algorithm is the simplest and most easily implemented | FIFO |
| in FIFO, after an active page is removed to bring in a new one, a ____ occurs almost immediately to retrieve the active page | page fault |
| a bad replacement choice increases the page-fault rate and slow process execution, but does not cause _____ execution | incorrect |
| in FIFO, as a general rule, the more frames available in physical memory, the ____ the page-fault rate | lower |
| what do you call the instance where the page-fault rate may increase with more frames available in physical memory? | Belady's Anomaly |
| this PR algorithm suffers from Belady's Anomaly | FIFO |
| this PR algorithm has the lowest page-fault rate of all algorithms | OPTIMAL |
| in this PR algorithm, the page that will be replaced is the one that will not be used for the longest period of time | OPTIMAL |
| the optimal algorithm is ____ as good as FIFO | twice |
| this PR algorithm is difficult to implement, since it requires future knowledge of the reference string | OPTIMAL |
| this PR algorithm is mainly used for comparison studies | OPTIMAL |
| this PR algorithm uses the recent past to approximate the near future | LEAST RECENTLY USED (LRU) |
| this PR algorithm replaces the page that has not been used for the longest period of time | LEAST RECENTLY USED (LRU) |
| this policy is often used as a page replacement algorithm and is considered to be quite good | LRU policy |
| in this PR algorithm, the OS maintains a stack of page numbers | LEAST RECENTLY USED (LRU) |
| the major problem in this PR algorithm is how to implement it | LEAST RECENTLY USED (LRU) |
| the main requirement of secondary storage is to be able to store a very large amount of data _____ | permanently |
| the main requirement of ____ is to be able to store a very large amount of data permanently | secondary storage |
| one of the earliest secondary-storage media is the ____ | magnetic tape |
| this was too slow in comparison with the access time of main memory | magnetic tape |
| these provide the bulk of secondary storage for modern computer systems | magnetic disks |
| a _______ system has several disk platters | magnetic disk |
| each ________ has a flat circular shape, like a phonograph record | disk platter |
| a magnetic material, similar to that of a magnetic tape or floppy diskette, covers its two surfaces | disk platter |
| a disk platter is divided into concentric circles called _______ | tracks |
| these are rigid metal or glass platters covered with magnetic recording material | disks |
| the disk surface is logically divided into ____, which are subdivided into sectors | tracks |
| the disk surface is logically divided into tracks, which are subdivided into ______ | sectors |
| the ____ does not actually touch the surface of a disk | read/write head |
| this flies or floats only microns from the disk surface, supported by a cushion of air | read/write head |
| the read/write head flies or floats only ____ from the disk surface | microns |
| typical hard disks have a rotation speed from ____ to ____ rpm | 4500 to 7200 |
| a ____ rpm drive just hit the market | 10000 |
| the faster the rotation, the higher the _____ rate, but also the louder and hotter the __ | transfer; hard drive (HD) |
| you may need to cool a ____ rpm disk with an extra fan, or its life would be much shorter | 7200 |
| modern HD's read all sectors of a track in how many turns? | one |
| for disks, the _____ speed is constant | rotation |
| this is when the head contacts the disk surface and scrapes the recording medium off the disk, destroying data that had been there | head crash |
| this was used as an early secondary-storage medium, but the access time is much slower than that of magnetic disks | magnetic tape |
| these are currently used mainly for backup, for storage of infrequently used information, and as a medium for transferring information from one system to another | magnetic tapes |
| the system stores information by recording it _______ on the sector under the read-write head | magnetically |
| a _____ system has a separate read-write head for each track | fixed-head |
| this arrangement allows the computer to switch from track to track quickly, but it requires a large number of heads, making it expensive | fixed-head system |
| a ____ system has only one read-write head per surface and the system moves the head to access a particular track | moving-head |
| this type of disk system is slower but less expensive | moving-head system |
| in this disk system, all the tracks on one drive that can be accessed without moving the heads are called a cylinder | moving-head system |
| all the tracks on one drive that can be accessed without moving the heads are called a ______ | cylinder |
| these are disks coated with a hard surface, so the read-write head scans it directly on the disk surface without destroying the data | floppy disks |
| a ________, which was one of the most commonly used floppy diskettes, capable of storing 1.44 mb of data | 3.5-inch floppy diskette |
| a 3.5-inch floppy diskette is capable of storing how much data? | 1.44 mb |
| a disk normally has a ____________ indicating which files are on the disk | device directory |
| this lists the file by name, and includes such information as where on the disk the file is, and what are its length, type, owner, time of creation, time of last use, protections, and so on | device directory |
| the system stores this on the device, often at some fixed disk address, such as disk address 00001 | device directory |
| modern disks are addressed as large one-dimensional arrays of ________, the smallest unit of transfer | logical blocks |
| the size of a logical block is usually __ bytes, although some disks can be low-level formatted to choose a different logical block size such as ____ bytes | 512; 1024 |
| enumerate the 2 ways of reading and writing of data on disks | (1) CONSTANT LINEAR VELOCITY, (2) CONSTANT ANGULAR VELOCITY |
| in this type of reading and writing of data on disks, the density of bits (bits/unit length) per track is uniform | CONSTANT LINEAR VELOCITY (CLV) |
| in this type of reading and writing of data on disks, since the outer tracks are longer, the number of bits on the outer tracks is more than the number of bits on the inner tracks | CONSTANT LINEAR VELOCITY (CLV) |
| in CLV (constant linear velocity), the number of bits on the ____ tracks is more than the number of bits on the ____ tracks | outer; inner |
| in this type of reading and writing of data on disks, the drive increases its rotation speed as the head from the outer to the inner tracks to keep the same rate of data moving the head | CONSTANT LINEAR VELOCITY (CLV) |
| in CLV (constant linear velocity), the drive _____ its rotation speed as the head from the outer to the inner tracks to keep the same rate of data moving the head | increases |
| this type of reading and writing of data on disks is used in CD-ROM and DVD-ROM drives | CONSTANT LINEAR VELOCITY (CLV) |
| in this type of reading and writing of data on disks, the drive spins the disk at a constant speed | CONSTANT ANGULAR VELOCITY (CAV) |
| in this type of reading and writing of data on disks, the number of bits per track is uniform (constant number of sectors) | CONSTANT ANGULAR VELOCITY (CAV) |
| in this type of reading and writing of data on disks, the density of bits per track increases from outer tracks to inner tracks | CONSTANT ANGULAR VELOCITY (CAV) |
| in CAV (constant angular velocity), the density of bits per track increases from ____ tracks to ____ tracks | outer; inner |
| this type of reading and writing of data on disks is used in hard disks and floppy disks | CONSTANT ANGULAR VELOCITY (CAV) |
| enumerate the 3 parameters that affects access time of a sector | (1) SEEK TIME, (2) LATENCY TIME, (3) TRANSFER TIME |
| this is the time it takes to move the read-write head to the correct track | SEEK TIME |
| this is the time it takes for the sector to rotate under the head | LATENCY TIME |
| this is the time it takes to actually trasfer data between disk and main memory | TRANSFER TIME |
| before a computer can make use of a new disk, the disk must be broken into the sectors that the computer can understand; this is called ______ | physical formatting |
| when ______, a disk consists of a set of sectors on each track the head can address | formatted |
| each sector has a header containing the ____ number and space for _______________ | sector; error correcting code (ECC) |
| for a computer to start running (from rebooting or powering up), it needs to have an initial program to run called the ______ | bootstrap program |
| the bootstrap program is stored in the _______ | boot block |
| this initializes all aspects of the system, from CPU registers to device controllers to memory contents | bootstrap program |
| because disks have moving parts and small tolerances, they are prone to _____ | failure |
| sometimes the failure is ____, and the disk needs to be replaced | complete |
| since there is only a limited amount of disk space, it is necessary to reuse the space from ____ files for new files | deleted |
| to keep track of the free disk space, the system maintains a _______ | free-space list |
| this is a free-space list implementation where a single bit represents each block on the disk | bit vector |
| in this free-space list implementation, if the block is free, the bit is 0; otherwise, the bit is 1 | bit vector |
| the main disadvantage of this free-space list implementation is that the OS often keeps this bit map in main memory | bit vector |
| enumerate the 4 free-space list implementations | (1) BIT VECTOR, (2) LINKED LIST, (3) GROUPING, (4) COUNTING |
| this free-space list implementation links all the free disk blocks together, keeping a pointer to the first free block | linked list |
| this free-space list implementation however, is not efficient because of the sequential nature of lists | linked list |
| this free-space list implementation is a modification of the free-list approach | grouping |
| in this free-space list implementation, the addresses of n free blocks are stored in the first free block, and so on | grouping |
| in grouping, the last one of the n free blocks contains a pointer to what? | the next group of n free blocks |
| the importance of this free-space list implementation is that the addresses of a large number of free blocks can be found quickly | grouping |
| this free-space list implementation takes advantage of the fact that, generally, several contiguous blocks may be allocated or freed simultaneously | COUNTING |
| in this free-space list implementation, rather than keeping a list of n free disk addresses, the system keeps the address of the first free block and the number n of free contiguous blocks that follow the first block | counting |
| in this free-space list implementation, each entry in the free-space list then consists of a disk address and a count | counting |
| enumerate the 3 disk allocation methods | (1) CONTIGUOUS, (2) LINKED, (3) INDEXED |
| this disk allocation method requires each file to occupy a set of contiguous addresses on the disk | contiguous |
| in this disk allocation method, if the file is n blocks long, and starts at location b, then it occupies blocks b, b+1, b+2, ..., b+n-1 | contiguous |
| in contiguous allocation, if the file is n blocks long, and starts at location b, then it occupies blocks b to ____ | b+n-1 |
| in this disk allocation method, the directory entry for each file indicates the address of the starting block and the length of the area allocated for this file | contiguous |
| this disk allocation method is where each file is a linked list of disk blocks; the disk blocks may be scattered anywhere on the disk | linked |
| in disk allocation method, the directory contains a pointer to the first and last blocks of the file | linked |
| in this disk allocation method, there is no external fragmentation | linked |
| in linked allocation method, there is no _____ fragmentation | external |
| in this disk allocation method, any free block on the free-space list can be used to satisfy a request | linked |
| in this disk allocation method, a file can also continue to grow as long as there are free blocks on the disk | linked |
| a disadvantage of this disk allocation method is that the pointers also occupy precious disk space | linked |
| an important variation on the linked allocation method is the use of the _________ | file-allocation table (FAT) |
| this table has one entry for each disk block, and is indexed by block number | file-allocation table (FAT) |
| this disk allocation method introduces the file-allocation table (FAT) | linked |
| the OS uses this table much like a linked list | file-allocation table (FAT) |
| when using the FAT, the ______ contains the block number of the first block of the file | directory |
| in FAT, the chain continues until the last block, which has a special _____ value in the table entry | end-of-file (EOF) |
| this disk allocation method is similar to linked allocation, except for the fact that pointers to the blocks are not scattered but are grouped in one location | indexed |
| in indexed allocation method, the pointers to the blocks are not scattered but are grouped in one location called the ____ | index block |
| in this disk allocation method, each file has its own index block, which is an array of disk-block addresses | indexed |
| this is an array of disk-block addresses | index block |
| the ith entry in the _____ points to the ith block of the file | index block |
| in indexed allocation method, the directory contains the address of the _________ | index block |
| this disk allocation method supports direct access, without suffering from external fragmentation | indexed |
| this disk allocation method however suffers from wasted space because it allocates an entire block, even if only one or two pointers will be non-nil | indexed |
| in indexed allocation method, the pointer overhead of the index block is generally _____ than the pointer overhead of linked allocation | greater |
| the OS can improve on the average disk service time by _________ the requests for disk access | scheduling |
| if the desired disk drive and controller are available, it can service the request __________ | immediately |
| while the drive or controller is serving one disk request, any additional requests, normally from other processes, should go to a _____ | queue |
| enumerate the 6 disk scheduling algorithms | (1) FIRST-COME, FIRST-SERVED (FCFS), (2) SHORTEST SEEK TIME FIRST (SSTF), (3) SCAN, (4) C-SCAN, (5) LOOK, (6) C-LOOK |
| this disk scheduling algorithm is the simplest form of scheduling | first-come, first-served (FCFS) |
| this is the count of how much tracks the head passes over in traversing to all the requested tracks | total head movement |
| this disk scheduling algorithm selects the request with the minimum seek time from the current head position | shortest seek time first (SSTF) |
| in this disk scheduling algorithm, the system moves the head to the closest track in the request queue | shortest seek time first (SSTF) |
| this disk scheduling algorithm would result in a substantial improvement in average disk service time | shortest seek time first (SSTF) |
| the problem with this disk scheduling algorithm is that it may cause starvation of some requests | shortest seek time first (SSTF) |
| the problem with the SSTF algorithm is that it may cause _____ of some requests | starvation |
| this is when in theory, a continual stream of requests near one another could arrive which causes the request for a farther track to wait indefinitely | starvation |
| this disk scheduling algorithm, although a substantial improvement from FCFS, is not optimal | shortest seek time first (SSTF) |
| in this disk scheduling algorithm, the read-write head starts at one end of the disk, and moves toward the other end, servicing requests as it reaches each track, until it gets to the other end of the disk | SCAN |
| in this disk scheduling algorithm, when it gets to the other end, the direction of head movement reverses and servicing continues | SCAN |
| this disk scheduling algorithm is sometimes called the elevator algorithm | SCAN |
| the scan scheduling algorithm is sometimes called the ______ algorithm | elevator |
| this disk scheduling algorithm is a variant of the SCAN algorithm | C-SCAN |
| in this disk scheduling algorithm, when it reaches the other end, it immediately returns to the beginning of the disk without servicing any requests on the return trip | C-SCAN |
| this disk scheduling algorithm essentially treats the disk as though it were circular, with the last track adjacent to the first one | C-SCAN |
| in this disk scheduling algorithm, the head is only moved as far as the last request in each direction | LOOK |
| in this disk scheduling algorithm, as soon as there are no requests in the current direction, the head movement is reversed | LOOK |
| this disk scheduling algorithm is a variant of the LOOK algorithm | C-LOOK |
| in this disk scheduling algorithm, after reaching the last request in the current direction, the head immediately returns to the first of the remaining requests while maintaining direction | C-LOOK |
| these two disk scheduling algorithms are more appropriate for systems that place a heavy load on the disk | SCAN, C-SCAN |
| if the queue seldom has more than one outstanding request, then all scheduling algorithms are effectively equivalent and ____ is a reasonable algorithm due to its simplicity | FCFS |
| this plays a key role in computer system security | the OS |
| any vulnerability at the OS opens the entire system to ____ | attack |
| the more complex and powerful the OS, the _____ it is to have vulnerabilities to attack | more likely |
| they must be on guard to arm their OS with all available defenses against attack | system administrators |
| this is the capability of a system to fulfill its mission, in a timely manner, in the presence of attacks, failures, or accidents | system survivability |
| enumerate the 4 key properties of survivable systems | (1) resistance to attacks, (2) recognition of attacks/damage, (3) recovery of services, (4) adaptation of defense mechanisms |
| this key property of a survivable system are strategies for repelling attacks | resistance to attacks |
| authentication is under what key property of a survivable system? | resistance to attacks |
| access controls is under what key property of a survivable system? | resistance to attacks |
| encryption is under what key property of a survivable system? | resistance to attacks |
| message filtering is under what key property of a survivable system? | resistance to attacks |
| system diversification is under what key property of a survivable system? | resistance to attacks |
| functional isolation is under what key property of a survivable system? | resistance to attacks |
| this key property of a survivable system are strategies for detecting attacks and evaluating damage | recognition of attacks/damage |
| intrusion detection is under what key property of a survivable system? | recognition of attacks/damage |
| integrity checking is under what key property of a survivable system? | recognition of attacks/damage |
| this key property of a survivable system are strategies for limiting damage, restoring compromised information/functionality, and so on | recovery of services |
| redundant components is under what key property of a survivable system? | recovery of services |
| data replication is under what key property of a survivable system? | recovery of services |
| system backup and restoration is under what key property of a survivable system? | recovery of services |
| contingency planning is under what key property of a survivable system? | recovery of services |
| this key property of a survivable system are strategies for improving system survivability based on knowledge gained from intrusions | adaptation of defense mechanisms |
| intrusion recognition patterns is under what key property of a survivable system? | adaptation of defense mechanisms |
| the _________ must evaluate the risk of intrusion for each computer configuration, which in turn depends on the leve lof connectivity given to the system | system administrator |
| enumerate the 3 kinds of computer configurations | (1) single computer (w/o email or internet), (2) LAN connected (w/o internet), (3) LAN connected (w/ internet) |
| this computer configuration's vulnerabilities are compromised passwords and viruses | single computer (w/o email or internet) |
| this computer configuration's vulnerabilities are sniffers and spoofing | LAN connected (w/o internet) |
| this computer configuration's vulnerabilities are e-mail, web servers, FTP, and Telnet | LAN connected (w/ internet) |
| a single computer (w/o email or internet) has what ease of protection? | high |
| a LAN connected (w/o internet) has what ease of protection? | medium |
| a LAN connected (w/ internet) has what ease of protection? | low |
| a single computer (w/o email or internet) has what relative risk? | low |
| a LAN connected (w/o internet) has what relative risk? | medium |
| a LAN connected (w/ internet) has what relative risk? | high |
| many system managers use a _____ backup schedule | layered |
| backups, with one set stored off-site, are crucial to _______ recovery | disaster |
| written policies and procedures and regular user training are essential elements of ____ management | system |
| a gap in system security can be _____ or not | malicious |
| these can be classified as a purposeful disruption of the system's operation | intrusions |
| these can be classified as something that happens due to uneducated users and unauthorized access to system resources | intrusions |
| an example of this is hardware malfunctions, undetected errors in OS/apps, or natural disasters | accidental/unintentional intrusions |
| this is any breach of security or modification of data that was not the result of a planned intrusion | accidental/unintentional intrusions |
| an example of this is the accidental incomplete modification of data | accidental/unintentional intrusions |
| an example of this is errors due to incorrect storage of data values | accidental/unintentional intrusions |
| when a data value is too large for the field, _______ replaces the data with asterisks | FORTRAN |
| when a data value is too large for the field, _______ truncates the higher order digits and stores only the digits that remain | COBOL |
| enumerate the 5 types of intentional attacks | (1) intentional unauthorized access, (2) viruses/worms, (3) trojan horses, (4) bombs, (5) blended threats (IVTBB) |
| this type of intentional attack includes denial of service attacks, browsing, wire tapping, repeated trials, trap doors, and trash collection | intentional unauthorized access |
| this is when a malicious hacker takes over computers via the internet and causes them to flood a target site with demands for data and other small tasks causing a computer to perform repeated unproductive task | denial of service (DoS) attack |
| this is when unauthorized users gain access to search through secondary storage directories or files for information they should not have the privilege to read | browsing |
| this is when unauthorized users monitor or modify a user's transmission | wire tapping |
| this refers to entering systems by guessing authentic passwords | repeated trials |
| this refers to an unspecified and undocumented entry point into a system | trap doors |
| this is installed by a system diagnostician or programmer for future use | trap doors |
| this leaves the system vulnerable to future intrusion | trap doors |
| trap doors are installed by a ______ or programmer for future use | system diagnostician |
| this refers to the use of discarded materials such as disks, CDs, printouts, etc. to enter the system illegally | trash collection |
| this type of intentional attack are small programs written to alter the way a computer operates, without permission of the user | viruses |
| enumerate the 2 criteria of a virus | (1) self-executing, (2) self-replicating |
| this type of intentional attack is usually written to attack a certain OS or application | viruses |
| this type of intentional attack is spread via a wide variety of applications | viruses |
| this kind of virus works by attaching itself to a template (such as NORMAL.DOT), which in turn is attached to word processing documents | macro virus |
| a _______ virus attacks a clean file by attaching a small program to it | file infector |
| enumerate the 5 types of virus | (1) file infector, (2) boot sector, (3) master boot record, (4) multipartite, (5) macro (FBMMM) |
| this type of virus infects files on the computer, normally .exe and .com files commonly found on Microsoft OS | file infector |
| these viruses commonly become resident in memory and then infect any clean .exe file that runs on that computer | file infector |
| this type of virus infects the boot record, the system area of a floppy disk or hard drive | boot sector |
| these viruses activate whenever the user boots up the computer | boot sector |
| most boot sector viruses were written for _____, but other OS are potential targets | MS-DoS |
| this type of virus infects the boot record of a disk, saving a legitimate copy of the master boot record in a different location on the volume | master boot record |
| this type of virus infects both the boot record and program files, making them difficult to repair | multipartite |
| successful removal of this virus requires that all instances of the virus be removed at once, on the boot records as well as all instances if files infected with it | multipartite |
| should any instance of the infection from this virus remain, the virus will reinfect the system | multipartite |
| this type of virus infects data files (such as documents, spreadsheets, etc.) though newer versions now infect other program files as well | macro |
| to avoid this type of virus, we are advised to disable their automatic execution on files we don't completely trust | macro |
| this type of intentional attack is a program that appears to be harmless but actually does something other than what it claims to do | trojan horse |
| this type of intentional attack is a program that is designed to be destructive triggered either by an event or time | bomb |
| this type of bomb is a destructive program with a fuse and a certain triggering event (keystroke, internet, etc.) | logic bomb |
| this type of bomb is a destructive program that is triggered by a specific time, such as a day of the year | time bomb |
| this type of bomb spreads unnoticed throughout a network | logic bomb |
| this type of intentional attack is a combination of other attacks into one program | blended threats |
| these are programs that reside on computers attached to the network, perusing data packets as they pass by, examining each one for information | sniffers |
| this is the act of disguising a communication from an unknown suorce as being from a known, trusted source | spoofing |
| this is done when unauthorized users want to disguise themselves as friendly sites (hoax sites) | spoofing |
| these are sites that are designed to look like a legitimate site, but are actually unauthorized | hoax sites |
| this is a technique whereby system intruders gain access to information about a legitimate user to learn active passwords | social engineering |
| looking in and around the user's desk for a written reminder is an example of what? | social engineering |
| trying the user logon ID as the password is an example of what? | social engineering |
| searching logon scripts is an example of what? | social engineering |
| telephoning friends/co-workers to learn the names of user's family members, pets, vacation destinations, etc. is an example of what? | social engineering |
| phishing is under what? | social engineering |
| this is the act of fraudulently using email to try to get the recipient to reveal personal data | phishing |
| in a _____ scam, con artists send legitimate-looking emails urging the recipient to take action to avoid a negative consequence or to receive a reward | phishing |
| spear-phishing is under what? | social engineering |
| this is a variation of phishing in which the phisher sends fake emails to a certain organization's employees | spear-phishing |
| this variation of phishing is called that way because the attack is much more precise and narrow in scope | spear-phishing |
| smishing is under what? | social engineering |
| this is a variation of phishing that involves the use of Short Message Service (SMS) texting | smishing |
| in a _____ scam, people receive a legitimate-looking text message on their phone telling them to call a specific phone number or to log on to a Web site | smishing |
| vishing is under what? | social engineering |
| this is a variation of phishing except the victims receive a voice mail telling them to call a phone number or access a Web site | vishing |
| rootkits are under what? | social engineering |
| this is a set of programs that enables its user to gain administrator-level access to a computer without the end user's consent or knowledge | rootkits |
| once this is installed, the attacker can gain full control of the system | rootkits |
| ransomware is under what? | social engineering |
| this is a malware that disables a computer or smart-phone until the victim pays a fee | ransomware |
| there is ___ single guaranteed method of protection | no |
| file downloads, e-mail exchange are under what? | system vulnerabilities |
| vulnerable firewalls are under what? | system vulnerabilities |
| improperly configures internet connections, etc. are under what? | system vulnerabilities |
| we need ______ attention to security issues | continuous |
| a Trojan horse or worm consists ________ of malicious code | entirely |
| this is a software to combat viruses that can be preventative, diagnostic, or both | antivirus software |
| this kind of antivirus software may calculate a checksum for each production program | preventative |
| this kind of antivirus software compares file sizes, looks for replicating instructions, or unusual file activity | diagnostic |
| this can sometimes remove the infection and leave the remainder intact | antivirus software |
| antivirus cannot repair worms, Trojan horses, or blended threats as they are what? | entirely malicious |
| this is a set of hardware/software designed to protect a system by disguising its IP address from unauthorized users | firewall |
| this sits between the internet and network | firewall |
| this blocks curious inquiries and potentially dangerous intrusions from outside the system | firewall |
| packet filtering and proxy servers are mechanisms used by the ____ | firewall |
| they often log activities that access the internet | firewall |
| they often maintain access control based on senders' or receivers' IP addresses | firewall |
| they maintain access control based on services that are requested | firewall |
| they hide internal network from unauthorized users | firewall |
| they verify that virus protection is installed and enforced | firewall |
| they perform authentication based on the source of a request from the internet | firewall |
| this is a verification that an individual trying to access a system is authorized to do so | authentication |
| this is a network authentication protocol designed to provide strong authentication for client/server applications by using secret-key cryptography | Kerberos |
| using Kerberos, when client A attempts to access server B, user is authenticated, and receives a ____ for the session | ticket |
| using ____, when client A attempts to access server B, user is authenticated, and receives a ticket for the session | Kerberos |
| this is the most extreme protection method for sensitive data where data is put into a secret code | encryption |
| to communicate with another system, data is encrypted, transmitted, decrypted, and processed with the process | encryption |
| in encryption, the sender inserts _____ key with the message | public |
| in encryption, the message receiver is required to have a _____ key to decode the message | private |
| a disadvantage of this protection method is that it increases system's overhead | encryption |
| a disadvantage of this protection method is that the system becomes totally dependent on the process itself | encryption |
| the 2 most basic techniques used to protect hardware and software investments include good _____ and careful user _____ | passwords; training |
| password files normally stored in ______ form | encrypted |
| the password _____ has a direct effect on the ability of password to survive cracking attempts | length |
| for passwords, use minimum of ____ characters (numeric and non-alphanumeric, lower and upper case) | 8 |
| for passwords, create a _____ word or join bits of phrases into a word easy to remember | misspelled |
| for passwords, you may follow a certain _____ on the keyboard or create ____ from memorable sentences | pattern; acronyms |
| for passwords, never use a word included in any _____ | dictionary |
| this is a method of breaking encrypted passwords that requires a copy of the encrypted password file and the algorithm used to encrypt the passwords | dictionary attack |
| to avoid _______, some OS "salt" user passwords with extra random bits | dictionary attacks |
| this is a credit card-sized calculator that requires both "something you have and something you know" | smart card |
| for security, the user must type in the number that appears at that moment on the _____ | smart card |
| for added protection in smart cards, user then enters a _______ | secret code |
| on the _____, user is admitted to the system only if both number and code are validated | smart card |
| this is the science and technology of identifying individuals based on unique biological characteristics of each person | biometrics |
| using human face, fingerprints, hand measurements, iris/retina, and voice prints for identification is called what? | biometrics |
| this positively identifies the person being scanned, but its critical factor is reducing the margin of error | biometrics |
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