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Comp 2 Definitions
Comp 2 - Definitions
Question | Answer |
---|---|
Boolean Variable | May have two discrete possible values. E.g. true or false |
Truth Table | A table that shows the results of applying the logical function to all possible combinations of inputs. |
OR function | The output is true if either or both inputs are true |
Boolean Equation | An equation that expresses a Boolean output Q in terms of Boolean inputs, X,Y,Z, etc…to which one or more Boolean functions, such as OR, AND and NOT are applied. |
AND function | The output is true if all inputs are true |
NOT function | The output is the inverse of the input. |
Logic Gate | An electronic circuit that performs a Boolean function |
Exclusive OR function | The output is true if either input is true but not if both inputs are true. |
NAND function | The output is true if any input is false |
NOR function | The output is true only when all inputs are false |
De Morgan’s Laws | A+AB=A.B and A.B=A+B |
Hardware | Electronic/electrical circuits that a computer is assembled from. The platform on which the software executes. |
Main Memory | Memory that is directly addressable by the processor |
Memory Location | A separately addressable area of main memory |
RAM | Random access memory. Volatile main memory in which the locations can be accessed directly in any order with the same access time for all writing and reading operations |
ROM | Read-only memory; non-volatile main memory that cannot be written to once it is set up. |
EEPROM | Electrically erasable programmable read-only memory; its contents may be altered but writing is about 100 times slower than reading. |
Computer Bus | A set of parallel wires connecting independent components of a computer system |
System bus or external bus | The main highway connecting the processor, main memory and I/O controllers; it is made up of a data bus, an address bus and a control bus. |
I/O | Allows the CPU to communicate with peripherals |
Clock Signal | Used for timing purposes |
Reset signal | Used to initialise components |
Memory read | Used to assert that the memory location currently in use is being read from. |
Memory write | Used to assert that the memory location currently in use is being written to |
I/O (control signal) | Used to indicate that the processor wishes to use an I/O controller not main memory when I/O and main memory share memory addresses. |
Peripheral | A computer device that is not part of the CPU. It can be external (e.g. mouse, keyboard, printer, monitor, memory stick or scanner. |
I/O device | A hardware unit that sends or receives data or stores data by communicating with the processor and main memory through an I/O controller |
I/O controller | An electronic circuit that connects to a system bus and an I/O device; it provides the correct voltages and currents for the system bus and the I/O device. |
Secondary Storage | Permanent storage memory not directly connected to the processor; also calling backing store |
Main Memory Address | A unique numeric code corresponding to a location in memory |
Stored Program Concept | A program must be resident in main memory to be executed; it is processed by fetching machine code instructions in sequence from main memory and executing them, one at a time, in the processor. |
Register | A very fast memory location inside the processor or I/O controller |
General-Purpose register | A register not assigned a specific role by the processor designer. Programmers may use general-purpose registers. |
Dedicated Register | A register assigned a specific role by the processor designer. Programmers may use some but not all dedicated registers. |
Clock Speed | Of a processor, the frequency in megahertz or gigahertz at which the processor executes instructions |
Word Length | The number of digits in a binary word |