1.1.1 Structure and functions of the processor

Question 1

What happens in the fetch stage?

Answer 1

1. The PC holds the address of the next instruction to be carried out
2. This address is copied into the MAR
3. The contents of the address in the MAR are copied into the MDR
4. The contents of the MDR is copied into the CIR
5. The contents of the PC is incremented

Question 2

What is the ALU?

Answer 2

Arithmetic logic unit

It does the arithmetical and logical calculations

Question 3

What is the control Unit?

Answer 3

The part of the CPU that manages the execution of instructions

Sends control signals around CPU

Question 4

What is a register?

Answer 4

Tiny areas of extremely fast memory, located inside the CPU

Question 5

What is the PC?

Answer 5

Program counter

A register inside the control unit which holds the address of the next instruction

Question 6

What is the accumulator?

Answer 6

It is used to hold the result of the ALU (Arithmetic logic unit)

Question 7

What is the MAR?

Answer 7

Memory Address Register

-A register in the CPU that holds the address of the memory location currently in use

Question 8

What is the MDR?

Answer 8

Memory Data Register

-Temporary stores data that has been or needs to be written

Question 9

What is the CIR?

Answer 9

Current Instruction Register
-A register inside the control unit that stores the memory address of the next instruction currently being decoded or executed

Question 10

What is the data bus?

Answer 10

This is a bi-directional used for for transporting data and instructions between components

Question 11

What is the address bus?

Answer 11

This the bus used to transmit the memory addresses specifying where data is to be sent to or retrieved from.The width of the address bus is proportional to the number of addressable memory locations.

Question 12

What is the control bus?

Answer 12

This is a bi-directional bus used to transmit control signals between internal and external components.

Question 13

Factors that affect CPU performance?

Answer 13

1. Clock speed
2. Amount of cores
3. Amount of cache

Question 14

What is pipelining?

Answer 14

The concurrent decoding of two or more machine instructions

Question 15

What 3 Characteristics of Von Neumann Architecture?

Answer 15

• Has a single control unit and single ALU
• Works sequentially through instructions
• Store instructions and data together in the same memory unit

Question 16

What 3 Characteristics of Harvard Architecture?

Answer 16

• The idea of the harvard architecture is to split the memory into two parts
• One part for data and another part for programs, each part is accessed with a different bus
• More expensive and difficult to program