Topic 7

Question 1

What is a backing store?

Answer 1

A non-volatile storage device

Question 2

What does a power supply do?

Answer 2

Converts alternating current to low-voltage direct voltage

Question 3

Name four tasks the processor is responsible for?

Answer 3

Sorting and searching data
Performing calculations
Logical decision making
Control of input, output and storage devices

Question 4

What is the bus system is composed of?

Answer 4

The bus system is composed of the communication links which connect the various parts of the computer

Question 5

What are the 3 buses?

Answer 5

Address bus
Data bus
Control bus

Question 6

Draw the bus diagram

Answer 6

xxx

Question 7

What does the main memory do?

Answer 7

Main memory stores program instructions and data that are processed by the processor

Question 8

What does the address bus do?

Answer 8

The address bus specifies a physical address in main memory and the value that is to be read or written into that address is communicated via the data bus

Question 9

What does the control bus do?

Answer 9

the control bus manages data processing; for example, sends a signal to either write from the data bus to a memory address or a signal to read data from a memory address

Question 10

Input and output - ______ _______ received from the _______ include input (read) or _____ (_____) requests. These control signals are the used to connect a ______ bus to specific I/O devices.

PROCESSOR
WRITE
CONTROL
SIGNALS
OUTPUT
SYSTEM

Answer 10

Input and output - control signals received from the processor include input (read) or output (write) requests. These control signals are the used to connect a system bus to specific I/O devices.

Question 11

What is Von Neumann’s architecture?

Answer 11

Data and instructions are both stored in the main memory

Question 12

Draw the Von Neumann architecture

Answer 12

What is Harvard architecture?

Question 13

Draw Harvard architecture

Answer 13

xxx

Question 14

What is addressable memory

Answer 14

What is addressable memory

Question 15

Why is addressable memory used?

Answer 15

the processor needs to be able to locate memory locations so each location is given a code

Question 16

How does the processor locate a memory location?

Answer 16

1. The processor writes the code into the address bus
2. The processor sends a request to the control bus with instructions to read or write to the memory location
3. The data that is being read from or written to will be transferred via the data bus

Question 17

What is the stored program concept?

Answer 17

Data and instructions are both stored in the main memory

Question 18

What is Harvard architecture?

Answer 18

data and instructions are stored separately

Question 19

What does the ALU do?

Answer 19

Performs mathematical and logical operations

Question 20

What does the control unit do?

Answer 20

Fetches instructions, decodes them, and executes

Question 21

What does the clock do?

Answer 21

Synchronises computer operations

Question 22

What does the register do?

Answer 22

Used to hold instructions and data temporarily

Question 23

What are general purpose registers used for?

Answer 23

Used to hold instructions and data temporarily

Question 24

What does the ACC register do?

Answer 24

Used as fast temporary storage by the ALU

Question 25

What does the SR register do?

Answer 25

The status register is a hardware register that contains information about the state of the processor

Question 26

What does the PC register do?

Answer 26

Holds the address of the next instruction to be used

Question 27

What does the MAR register do?

Answer 27

Holds the address of the current instruction being executed

Question 28

What does the MBR register do?

Answer 28

Holds the instruction from the (MAR) and the associated data

Question 29

What does the CIR register do?

Answer 29

Used to store the instruction that is to be decoded and executed

Question 30

Explain the ‘fetch’ part of the ‘fetch, decode, execute cycle’?

Answer 30

The PC points to the next instruction to be fetched
The contents of the PC are copied into the MAR
The contents of the MAR are transferred by the data bus to MBR
The contents of the MBR are copied to CIR
the PC is updated to the address of the next instruction

Question 31

Explain the ‘decode’ part of the ‘fetch, decode, execute cycle’?

Answer 31

The instruction in the CIR is decoded

Question 32

Explain the ‘execute’ part of the ‘fetch, decode, execute cycle’?

Answer 32

The decoded instruction is executed

The process is repeated

Question 33

What is the op-code?

Answer 33

Op-code is machine code instructions

Question 34

What is the operand

Answer 34

Is the value or memory address

Question 35

In a 16-bit operation, how many bits represent the op-code?

Answer 35

4 bits for the op-code

12 bits for the operand

Question 36

.

Answer 36

.

Question 37

What is direct/absolute addressing?

Answer 37

The code refers to a memory location
e.g
ADD (1302)
It adds the contents of address 1302 to the accumulator

Question 38

Why does assembly language exist?

Answer 38

It is used to make machine code easier to remember and read

Question 39

what does a # mean

LDR r1, #21

Answer 39

Loads THE NUMBER into the address r1