Components of a Computer Flashcards Preview

A-Level Computer Science OCR > Components of a Computer > Flashcards

Flashcards in Components of a Computer Deck (117)
Loading flashcards...
1

Arithmetic Logic Unit

Carries out calculations and logic (Comparisons of binary)

2

Control Unit

Control Unit is a register in the CPU that controls and co-ordinates the activity of the CPU. Control signals are sent along the control bus between the control unit and the other components of the computer.

3

Registers

Registers are small storage locations used to hold data temporarily. They have high read and write speeds.

4

Program Counter

stores the address of the next instruction

5

Memory Address register (MAR)

stores the address of instructions and data that need to be fetched from memory

6

Memory Data register (MDR)

stores the data which is to be sent or fetched from memory

7

Current instruction register

stores the actual instruction that is being decoded

8

Accumulator

stores the result of calculations made by the ALU

9

Interrupt register

generates and detects interrupts

10

Buses

the communication channels between the CPU and the memory and other components.

11

Address Bus

A one directional bus that transmits memory addresses that are used as operands in programming instructions, so that data can be retrieved from main memory

12

Data Bus

A bi-directional path for moving data and instructions between system components

13

Control Bus

A bi-directional bus to transmit command, timing and specific status information between system components

14

system bus

collective term for address, data and control bus

15

fetch decode execute cycle

PC
MAR
Address Bus
Memory
Data bus
MDR
CIR
Decode Unit

16

Fetch

1. The address of the next instruction is copied from the PC to the MAR
2. The fetch signal is sent across the control bus. The content of the MAR are transferred across the address bus.
3. The contents of the memory location stored in the MAR are sent across the data bus and stored in the CIR
4. the PC increments by 1

17

Decode

The contents of the CIR are sent to the CU and divided. The Opcode tells you the instruction to be carried out and the operand stores the address of any data which might be needed, the operand is sent to the MAR and the data is fetched from memory and stored in the MDR

18

Execute

The appropriate instruction/ opcode is carried out on the data/ operand

19

program branch reason

occurs due to an if statement, function, procedure call or loop.

20

program branch result

the next instruction held in the PC is not carried out

21

Clock speed

Indicates the number of instructions the CPU can process per second.

22

Clock speed Unit

Hertz (usually gigahertz)

23

Positives of increasing clock speed

you can carry out more instructions in a given time; improved performance

24

Negatives of increasing clock speed

more heat generated meaning computers must be cooled (either with heat sync/fan or water/oil cooling)

25

Cache memory

Special high speed memory used by a computer. Stores frequently used data and instructions.

26

Positives of increasing cache size

less time fetching data; improved performance

27

negative of increasing cache size

expensive

28

Multiple cores

Multiple CPUs working on a single computer

29

positives of multiple cores

may speed up processing

30

negatives of multiple cores

complicated circuitry (more expensive)
doesn't always improve performance