Characteristics of contemporary processors

Question 1

What is the ALU and what is its function?

Answer 1

The ALU completes all of the arithmetic and logical operation

Question 2

What is the control unit and what is its function?

Answer 2

Directs the operations of the CPU

Question 3

What is a register?

Answer 3

Registers are small memory cells that operate at a very high speed.

Question 4

What does the PC (program counter) do?

Answer 4

Holds the address of the next instruction to be executed

Question 5

What does the accumulator do?

Answer 5

Stores the result from a calculation.

Question 6

What does the MAR( Memory Address Register) do?

Answer 6

Holds the location that is to be read or written to

Question 7

What does the MDR (Memory Data Register) do?

Answer 7

Temporarily stores data that has been read or that needs to be written

Question 8

What does the CIR(Current Instruction Register) do?

Answer 8

Holds the current instruction being executed

Question 9

What is operand?

Answer 9

The data or memory location that is used to execute an insruction

Question 10

What is opcode?

Answer 10

The instruction executed by the CPU

Question 11

What is a bus?

Answer 11

A set of parallel wires that connect two or more components inside the CPU.

Question 12

What are the 3 busses in the CPU?

Answer 12

Data bus, control bus, address bus

Question 13

What does the data bus do?

Answer 13

This is a bidirectional bus (can go both ways). Used for transporting data and instructions between components.

Question 14

What does the address Bus do?

Answer 14

Transmits memory addresses.

Question 15

What does the control bus do?

Answer 15

This is a bidirectional bus (can go both ways). Used to transmit controls signals between the internal and external components.

Question 16

What is pipelining?

Answer 16

Pipelining is the process of completing the fetch, decode execute cycles of three separate instructions at the same time. Pipelining reduces the amount of the CPU that is kept idle.

Question 17

What happens in the fetch stage of the fetch execute decode cycle?

Answer 17

Fetch:
Address from the PC is copied to the MAR
Instruction held at address is copied to MDR
PC increased by 1
Value in MDR is copied to CIR

PC ->MAR
at address -> MDR
PC increase 1
MDR ->CIR

Question 18

What happens in the decode state of the fetch execute decode cycle?

Answer 18

The contents of the CIR are split into operand and opcode

Question 19

What happens in the execute stage of the fetch execute decode cycle?

Answer 19

The decoded instruction is executed.

Question 20

What factors affect the CPU’s performance?

Answer 20

Clock speed, number of cores and size of cache memory.

Question 21

How does clock speed affect the CPU’s performance?

Answer 21

Clock speed is the time taken for one clock cycle to complete

Question 22

How does the number of cores affect the CPU’s performance?

Answer 22

Every core can complete their own fetch execute decode cycle, more cores more fetch execute decode cycles at once.

Question 23

How does the amount of cache memory affect the CPU’s performance?

Answer 23

Cache memory is very quick small amounts of memory that is read and written to. The more quick memory you have the better.

Question 24

What is the structure of Von Neumann architecture?

Answer 24

A shared memory and data bus is used for both data and instructions, can only take one at a time

Question 25

What is the structure of Harvard architecture?

Answer 25

Two physically separate memories for instructions and data each with their own bus.

Question 26

What is contemporary processing?

Answer 26

Contemporary processing uses a combination of both Harvard and Von Neumann architecture. Uses Von Neumann for data and instructions but Harvard to divide the cache into instructions cache and data cache.

Question 27

What is RISC processing?

Answer 27

Reduced Instruction Set Computers, there is a small set of instructions with each instruction taking one clock cycles. They are very simple instructions such as add or minus however is not as complex as multiplication in one stage.

Question 28

What is CISC processing?

Answer 28

Complex Instruction Set Computer, there is a large instruction set. This type of processing aims for tasks to be accomplished in as few lines of assembly code as possible.

Question 29

What are the advantages of CISC processors?

Answer 29

Pipelining is possible since each instruction takes one clock cycle.
Less RAM required because code is shorter.
Compiler has less work to do to translate high level code into machine code.

Question 30

How does an optical device work?

Answer 30

Optical devices are read to and written to using lasers. Binary information is represented with the laser either being reflected or scattered- indicating if it is a 1 or a 0.

Question 31

How does a magnetic device work?

Answer 31

The magnetic device will be split into polarised and unpolarised states. If a portion is polarised or unpolarised it shows whether it has the binary value of 1 or 0.

Question 32

What are some examples of optical storage?

Answer 32

CDs, DVDs, Blu-ray

Question 33

What are some examples of magnetic storage?

Answer 33

Hard disk drives, Magnetic tape, Floppy disks.

Question 34

How does Flash storage work?

Answer 34

Flash storage is fast and compact, uses silicon semiconductors forming different logical gates.

Question 35

What are some examples of flash storage?

Answer 35

Solid State Drives