Components Of A Computer - 1.1.2

Question 1

What is a CPU?

Answer 1

The “brain” of the computer system

Question 2

What does the CPU do?

Answer 2

Processes all the data and instructions for the system to work

Question 3

What are the 3 main parts of a CPU?

Answer 3

CU ( Control Unit)
ALU ( Arithmetic Logic Unit)
Cache

Question 4

Function of the CU?

Answer 4

Overall control of the CPU, manages the fetch-decode-execute cycle

Question 5

Function of ALU? (4)

Answer 5

Does all the calculations
Performs logic operations (AND, OR, NOT)
Binary shifts
Contains the ACC

Question 6

Function of Cache (5):

Answer 6

Very fast memory, stores regularly used data so the CPU can access it quickly
Very low capacity and expensive
Different levels of cache
Slower than registers but faster than RAM
If data is not in cache it’s stored in the RAM

Question 7

What is the Von Neumann architecture?

Answer 7

Currently used data and software are stored in the RAM in memory addresses.

Question 8

What does the program counter do? (2)

Answer 8

Holds the memory address of the next instruction in the cycle
Found in the CU

Question 9

Function of the accumulator?

Answer 9

Stores the results of the calculations from the ALU
Found in the ALU

Question 10

Function of the MAR?

Answer 10

Holds any memory address that the CPU will use
Can be for data or instructions

Question 11

Function of an MDR?

Answer 11

Holds the actual data or instruction

Question 12

Explain the fetch-decode-execute cycle (7 steps):

Answer 12

1. PC starts at 1 and is copied to the MAR
2. PC increases by 1 ready for the next instruction
3. MAR fetches the data or instruction from that address in the RAM at and copies it to the MDR
4. CU decodes the data or instruction
5. The instruction is executed, e.g. loading data from memory, do a calculation in the ALU, change the PC address
6. Then copied to the ACC
7. Repeats.

Question 13

What does CPU performance depend on (5)?

Answer 13

Clock speed
Number of cores
Cache size
More RAM
GPU’s

Question 14

What is the Clock Speed (2)?

Answer 14

Number of instructions that can be carried out by a core per second (Hz)
Higher clock speed = greater number of instructions completed

Question 15

How does the number of cores affect CPU performance ?

Answer 15

Each core can process data independently
More cores = more instructions completed at once
4 cores in smartphones and PC’s

Question 16

How does cache size affect CPU performance?

Answer 16

Data storage that is much faster than RAM
Larger cache = CPU has faster access to more data

Question 17

How does RAM affect CPU performance?

Answer 17

Too little RAM = system may run too slowly and use virtual memory
More RAM = more applications remembered

Question 18

How do GPU’s help CPU performance?

Answer 18

Graphics processing units
Relieve processing load on the CPU

Question 19

What are busses?

Answer 19

Sequence of wires which carry electrical signals
3 types:
Address bus - carries memory addresses from processor to other components
Memory bus - carries data from processor to other components
Control bus - carries control signals

Question 20

What was Moore’s Law?

Answer 20

Observed that every two years the speed and capability of computers should double while the price halves

Question 21

What are the other components and functions (7)?

Answer 21

Power supply - supplies power to the motherboard and other hardware
Case cooling fan - extracts hot air from the computer case
CPU heat sink and cooling fan - keeps the CPU at a steady temperature
Optical drive - for read/writing of optical discs
RAM sticks - computer memory
Motherboard - main circuit board where all components are connected
Hard disk drive - internal secondary storage