Computer architecture

Question 1

Computer systems consist of software and hardware. What is meant by each term?

• Software
• Hardware

Answer 1

• Software: programs executed from a computer system/ instructions that tell the hardware what to do.
• Hardware: electrical component that makeup a computer system

Question 2

What is meant by the microprocessor or CPU?

Answer 2

A semiconductor chip that implements the central processor of the of a computer.The microprocessor is the component that executes instruction in a sequence.

Question 3

Name and describe the functions of the main components within the Von Neuman CPU.

Answer 3

1. Control Unit: provides the functionality required to control the movement of information between memory, the ALU an other portions of the machine.
   / is in charge of fetching the sequence it also decodes, synchronises and sends control signals between different internal parts.
2. ALU (Arithmetic Logic Unit): Forms functions of two input values and produces a single output result/ performs arithmetic and logical operations.
3. Registers: very small but fast storage located on the CPU
4. Buses: connect all internal components (CPU with main memory).

Question 4

Define Main Memory

Answer 4

Volatile memory that stores instructions and data which is directly accessible by the processor.

Question 5

Purpose of Main Memory

Answer 5

For storing programs that are currently being run and for data that is currently being processed.

Question 6

Example of what is stored in Main Memory

Answer 6

A spreadsheet with its data that a user is currently working on.

Question 7

Define Cache

Answer 7

Is small but fast memory which can be used by the processor much more quickly.

Question 8

Purpose of Cache

Answer 8

To be accessed quicker than RAM by the CPU.

Question 9

Example of what is stored in Cache

Answer 9

Instructions used for a loop that the processor is currently executing.

Question 10

Define Register

Answer 10

Small but fast temporary storage located on the CPU.

Question 11

Purpose of Register

Answer 11

Stores one instruction to be executed next.

Question 12

Example of what is stored in a Register

Answer 12

LDA#15 - Load number 15 into accumulator.

Question 13

Define ROM (Read Only Memory)

Answer 13

Series of instructions inside a computer that cannot be changed - non volatile.

Question 14

Purpose of ROM

Answer 14

For data and instructions that are fixed onto the ROM chip to start the computer.

Question 15

Example of what is stored in ROM

Answer 15

Configuration of the motherboard.

Question 16

Define EEPROM (Electronically Erasable Programmable Read Only Memory)

Answer 16

Is non volatile but the entire contents can be erased and reprogrammed.

Question 17

Purpose of EEPROM

Answer 17

Holds details of what is connected to the motherboard.

Question 18

Example of what is stored in EEPROM

Answer 18

Multiple numbers and configurations of RAM modules

Question 19

Example of secondary storage

Answer 19

Floppy disk

Question 20

Example of Main Memory

Answer 20

RAM

Question 21

What is meant by CACHE memory

Answer 21

CACHE is small but fast memory that can be used by the processor much quicker compared to RAM. While CACHE is quicker, RAM has a higher capacity. Also RAM is volatile memory that stores instructions and data which is directly addressable by the processor.
CACHE: parts of the program currently being used.
RAM: All running programs.

Question 22

Describe three differences between RAM and ROM?

Answer 22

• RAM is volatile
• ROM is non volatile
• RAM larger capacity
• ROM smaller capacity compared to RAM
• ROM does not require a constant source of power to retain information stored on it
• RAM does require a constant source of power to retain information. When power is turned off RAM will lose all information stored on it

Question 23

What is the difference between ROM and EEPROM?

Answer 23

ROM: Cannot be changed
EEPROM: Content can be erased and reprogrammed
ROM: Systems / Programs / Instructions to boot your computer
EEPROM: Configuration of the motherboard attached devices

Question 24

Computers utilise different types of cache memory. Two traditional types of RAM cache and disc cache. Describe in detail each type of cache memory.

Answer 24

1. On-chip cache: Area of microprocessor that contains cache memory.
2. Disc cache: Area of very fast memory between a hard drive and RAM.
3. RAM cache: Area of very fast memory between RAM and the microprocessor.
4. Web Cache: File containing recently accessed web pages.

Question 25

Another use of cache is storing internet pages temporarily on the computer's hard disc drive. Briefly describe the advantages of utilising this type of cache.

Answer 25

This cache (web cache) speeds up viewing because you can quickly view previously viewed pages.

Question 26

What is the highest address in a computer with 1K of memory?

Answer 26

2^10 - 1

Question 27

Give three examples of what can be stored in a 32 bit word.

Answer 27

Values / characters / integers

Question 28

A particular computer has 256 MB of RAM. How many bus wires are needed to address every Byte of this memory?

Answer 28

``` 1MB = 2^20 --(20 lines) 256MB = 2^20 * 2^8 = 2^28 -- (28 lines) ```

Question 29

Giving an example in each case, define the computer terms bit and byte.

Answer 29

Bit: One binary digit, smallest unit of data in a digital computer system, can store one value (Example: 0 or 1). Byte: A group of 8 bits (Example: 0101 0101).

Question 30

Define the computer term word. Give an advantage of a computer using a large word size compared with a computer using a small word size .

Answer 30

Word - the number of bits processed in one go in CPU. Advantage - quicker than smaller word size because it can transfer more bits in one go. / A word is the number of bits which can be addressable or transferred as a single unit at a time. A computer with a large word size will be faster compared to a computer with a smaller word size. Advantage: performance better because more instructions.

Question 31

What is meant by the stored program concept?

Answer 31

Program must be resident in Main Memory to be executed. From where they are fetched one after another, one at a time. Program can be replaced by loading another program into main memory.

Question 32

What is meant by a Von Neuman architecture?

Answer 32

Programs/ instructions and data are stored in one single store (MAIN MEMORY).

Question 33

Give two more names for immediate access store

Answer 33

RAM and Main memory

Question 34

Give another name for main memory

Answer 34

RAM

Question 35

If the data bus consists of 8 lines, what is the largest denary value which could be transferred in one go?

Answer 35

255

Question 36

What is the significance of the size of the address bus?

Answer 36

It determines the number of memory cells that can be accessed by the CPU

Question 37

Give two examples of a signal carried by the control bus

Answer 37

- Command signals | - Timing signals

Question 38

What are the names of the three buses

Answer 38

- Data bus - Control bus - Address bus

Question 39

A company has designed a new peripheral and is developing the I/O controller for it. What do we mean by the term peripheral?

Answer 39

A peripheral is a piece of equipment that can be attached to the central processing unit, e.g. hard disk, keyboard (I/O controller).

Question 40

Why are devices not connected directly to the processor?

Answer 40

It would slow the computer down because the devices would have to have a separate interpreter in order to communicate

Question 41

Name one other device controller which may be found in a typical microcomputer

Answer 41

Expansion card

Question 42

The data bus carries data in both directions. Explain why the address bus only carries addresses in one direction

Answer 42

Does so from processor to system components. It only goes in one direction so no outside devise can write into the microprocessor.

Question 43

What is meant by the clock speed of a processor

Answer 43

The number of pulses per second generated by an oscillator that sets the tempo for the processor

Question 44

How is clock speed measure?

Answer 44

in GHz

Question 45

What is the relationship between the word length and bus width of a processor?

Answer 45

Bus width - determines the number of bits that can be transmitted together. Word length - number of bits that the processor can process simultaneously

Question 46

Identify and describe three factors that affect the rate at which operations are carried out by the microprocessor.

Answer 46

1. Control Unit - coordinates the activities taking place in the processor memory and peripherals. 2. ALU - in which all arithmetic and logical operations are carried out. 3. System Clock - generates clock pulses to step the control unit through its operations.

Question 47

What is the effect on processor performance of increasing (1) clock speed, (2) word length and (3) data bus width?

Answer 47

1. If clock speed increases the speed at which instructions are executed increases in the processor. 2. The overall speed of the computer will increase with the increase of word length. 3. Determines the overall speed and performance.

Question 48

Why are microprocessors being designed with multiple cores?

Answer 48

- They become faster | - Clock frequency increases with multiple cores

Question 49

The internal components of a computer are connected by a bus. Briefly describe two roles of the bus

Answer 49

Data bus - carries data to and from memory | Address bus - carries the memory address to the next instruction to be executed.