Structure and Function of the Processor

Question 1

function of the processor

Answer 1

to execute instructions and manage the rest of the hardware

Question 2

ALU (arithmetic and logic unit)

Answer 2

completes all the arithmetic , logical and shift operations

Question 3

CU (control unit)

Answer 3

determines the sequence of operations to be executed from the ALU.

• controls and coordinates activities of the CPU
• manages the flow of data between the CPU and other devices
• accepting the next instruction to be executed in order
• decodes instructions
• stores results back into RAM

Question 4

Registers

Answer 4

small high speed memory locations used to store temporary data and where all ALU operations occur

Question 5

PC

Answer 5

holds the address of the next instruction to be executed

Question 6

ACC

Answer 6

temporarily stores the results from calculation

Question 7

MAR

Answer 7

stores the address of the memory location currently in use

In the fetch phase, this would be the address of the instruction being loaded; in the execute phase, it would be the address of the data being used.

Question 8

MDR

Answer 8

A register that contains the data to be stored in the computer storage, or the data after a fetch from the computer storage. It acts like a buffer and holds anything that is copied from the memory ready for the processor to use it.

Question 9

Busses

Answer 9

Physical pathways shared by signals connecting multiple components in the CPU

Data bus
Address bus
Control bus

Question 10

Data Bus

Answer 10

bi-directional

The part of the bus which carries data to and from components of the cpu

Question 11

Address Bus

Answer 11

The part of the bus which carries the address of where the data is being sent to and has been retrieved from.
FROM CPU TO RAM
unidirectional

Question 12

Control Bus

Answer 12

bi- directional.

carries control signals from the processor to every other component. The control bus also carries the clock’s pulses.

Question 13

Control Signals

Answer 13

• Bus request: device requesting the use of data bus
• Bus grant: CPU granted access to data bus
• Memory write: data written into the addressed location using this bus
• Memory read: data is read from a specific location to be placed onto the data bus,
• Interrupt request: shows that a device is requesting access to the CPU
• Clock: used to synchronise operations

Question 14

Pipelining

Answer 14

Process of executing separate instructions simultaneously. {As once and instruction is processed, the next instruction is fetched and one is decoded}

resembles the production line known as (overlapping )and is aimed to improve the efficiency of the processor.

Question 15

Pipelining Pros

Answer 15

• reduces the times that the CPU is kept idle
• increases the throughput of the system
• makes the system reliable
• cycle processor time is reduces so more instructions are executed per second

Question 16

Pipelining Cons

Answer 16

• Complex/ costly to manufacture

- instruction latency is more

Question 17

Instruction pipelining

Answer 17

divides instructions into series of steps {fetch, decode, execute}

Question 18

Arithmetic pipelining

Answer 18

divides an arithmetic problem into various sub problems and overlapping them as they are performed

Question 19

Fetch-Decode-Execute Cycle

Answer 19

• Address from PC copied to MAR
• Instruction held at that address is copied to MDR by the data bus
• Simultaneously, contents of the PC are incremented by + 1
• value held in the MDR is copied to the CIR
• The contents of CIR are decoded and executed. results are stored ACC.

Question 20

Factors affecting the performance of the CPU

Answer 20

Clock speed
Number of cores
Cache

Question 21

Clock speed

Answer 21

Measured in Hertz, the clock speed is the frequency at which the internal clock generates pulses. The higher the clock rate, the faster the computer will execute instructions per second.

The clock is the electronic unit that synchronizes related components by generating pulses at a constant rate.

Question 22

Number of cores

Answer 22

CPUs with multiple cores have more power to run multiple programs at the same time. Therefore, if we increase the number of cores in a processor, there will be an increase in system performance.

Question 23

Cache size

Answer 23

a larger cache size means more programs and instructions can be stored in cache which can be accessed faster than RAM.

Question 24

Von Neumann Architecture

Answer 24

Traditional computer architecture that forms the basis of most digital computer systems. A single control unit manages program control flow following a linear sequence of fetch-decode-execute

Question 25

Harvard Architecture

Answer 25

A computer architecture with physically separate storage and signal pathways for instructions and data. These early machines had data storage entirely contained within the central processing unit, and provided no access to the instruction storage as data.

Question 26

Contemporary Processing

Answer 26

Any modern set of disciplines that describes the functionality, the organization and the implementation of computer systems.

Question 27

CIR

Answer 27

A register in the control unit that stores the address of the instruction currently being executed and decoded.