1.1.1 Processors, input, output and storage

Question 1

Computer

Answer 1

A computer can process an input from a user in order to reach an output

Question 2

CPU

Answer 2

Central processing unit

Question 3

What does a CPU design depend on

Answer 3

What it is being used for

e.g. phone is smaller than a PC and is battery powered without a fan so it needs a smaller CPU with less functions

Question 4

Components of a CPU

Answer 4

Control Unit
Buses
Arithmetic Logic Unit
Designated Registers

Question 5

Control unit

Answer 5

Processes instructions for the CPU

Question 6

Buses

Answer 6

Move signals around
Consist of connectors that transfer signals between components
8/16/32/64 lines

Question 7

3 types of bus

Answer 7

Address bus - where it is going ; CPU to RAM
Data bus - carries the data around ; both ways
Control bus - controls data instructions ; both ways

Question 8

Arithmetic logic unit

Answer 8

Carries out arithmetic and outputs - stores results in the accumulator

Question 9

CIR

Answer 9

Current instruction register

Holds the current instruction that is being followed

Question 10

PC (register)

Answer 10

Program counter

Memory address of the next instruction

Question 11

MAR

Answer 11

Memory address register

Holds the address of where data is being read/written

Question 12

MDR

Answer 12

Memory data register

Holds data between processor and memory

Question 13

AC

Answer 13

Accumulator

Stores the result of logical calculations

Question 14

What must you call registers by?

Answer 14

Their full names - NO ACRONYMS

Question 15

Fetch

Answer 15

CPU fetches data and stores in registers

1. PC transfers address of next instruction to MAR
2. Instruction from that address is carried to MDR
3. Simultaneously PC value increases by 1
4. Contents of MDR are transferred to CIR

Question 16

Decode

Answer 16

5. Instruction held in CIR is decoded
6. Split into operand and opcode to define the type of instruction and acquire any additional data
7. Passed to ALU

Question 17

Execute

Answer 17

8. Instruction is executed and result stored in accumulator or memory

Question 18

Operand and opcode

Answer 18

opcode has the instruction

operand has the data and address.

Question 19

Words

Answer 19

The equal units memory is divided into, usually 8/16/32/64 bits
Each has a separate memory address

Question 20

Address bus

Answer 20

The width determines the maximum possible memory addresses (2 to the power of width addresses)

Question 21

Hexadecimal machine code instruction

Answer 21

8 bits opcode - 6 instruction, 2 clarify what

8 bits operand

Question 22

Factors affecting performance

Answer 22

Clock speed
Number of core
Cache memory
Buses

Question 23

How does clock speed affect performance?

Answer 23

It increases the speed of the fetch/decode/execute cycle.
The faster clock speed the more instructions executed per second.
You can overclock if the clock speed is too high

Question 24

How does the number of cores affect performance?

Answer 24

They can process more instructions simultaneously

Parallel processing - where multiple cores work on different elements of the same task to complete it quicker

Question 25

Cache memory

Answer 25

A small amount of superfast memory that stores recent data and instructions
Level 1 cache smaller but faster, cores share level 2
More allows for better performance

Question 26

How can buses affect performance?

Answer 26

A bigger address bus allows you to have more address locations, storing more data and instructions

Question 27

Methods to improve the performance of a computer

Answer 27

Changing CPU for clock speed/ more cores/ more cache
More or faster RAM
Change graphics card
SSD (Solid state drive)

Question 28

Pipelining

Answer 28

Overlapping stages of the F/D/E cycle to improve performance
One line is executed as the next is decided and the one after that fetched
Data is held in a buffer

Question 29

Issues with pipelining

Answer 29

Conditionals from instructions you have executed may mean you now need different instructions, negating the gain by fetching and decoding others before.

Question 30

Register definition

Answer 30

Small memory cells that operate at a higj speed. They store data and operations are carried out on data in them

Question 31

Clock

Answer 31

An electronic device which generates signals, switching between 0 and 1. The clock speed is measured in Hz

Question 32

Core

Answer 32

An independent processor able to carry out its own F/D/E cycle