Key Area 1.4 - Low Level Operation and Structure

Question 1

What is the control unit

Answer 1

This sends control signals which allow data to be stored in memory, fetched from memory and which decode and carry out instructions

Question 2

What is the ALU

Answer 2

The arithmetic and logic unit
This carries out all of the computer arithmetic (addition subtraction multiplication) and logical (IF AND OR =) functions

Question 3

What are the registers

Answer 3

The storage locations that are internal to the processor
They are used to store data that is being transferred to and from memory and hold the addresses of the location in memory which the processor is accessing to read or write data. It holds the instructions that are currently being carried out

Question 4

What is main memory

Answer 4

Main memory can be either rom or ram
ROM is system memory which holds the system information
RAM is the working space of the computer and holds all the data and files currently in use by the system

Question 5

Give the properties or RAM

Answer 5

Random Access Memory
The processor can read to or write from RAM quickly
Data held here can be edited
Data held here is lost when the power is turned off
RAM holds all the data and programs currently in use

Question 6

Give the properties of ROM

Answer 6

Read Only Memory
Data here cannot be edited and is stored permanently
Data us nit lost when the power is turned off
Holds vital system data and programs

Question 7

What is a bus

Answer 7

Buses are used as transmitters between different parts of a computer system

Question 8

What is the data bus

Answer 8

The data bus is used to carry data to and from the CPU and memory. Each line on a data bus will carry one binary word

Question 9

What is the address bus

Answer 9

The address bus holds the memory location of where data is about to be stored or from which data is about to be read

Question 10

What is the control bus

Answer 10

The control bus is a series of independent control lines used to send out control signals such as
Read from
Write to

Question 11

What is the fetch execute cycle

Answer 11

The computers memory RAM stores the program and data instructions while they are being used
The processor then decides and carries ur each program instruction
These instructions often involve fetching and processing the data stored in memory

Question 12

What is an interface

Answer 12

An interface is the combustion of hardware and software needed to link the processor to the peripherals and is the means by which independent systems can communicate
They can
Change electrical voltages
Deal with control signals
Change analogue data into digital data
Store incoming data

Question 13

What is ASCII

Answer 13

American Standard Code for Information Interchange

Holds 8 bits therefor 256 characters

Question 14

What is Unicode

Answer 14

Contains every character based alphabet, ideographical languages, punctuation and control signs

Question 15

Show the progress of memory size

Answer 15

Bit
Byte
Kilobyte
Megabyte
Gigabyte
Terabyte

Question 16

What is machine code

Answer 16

The language that the computer understands at the lowest level. This is very difficult to read.
Programs written in high level languages must be translated into machine code

Question 17

What is an interpreter

Answer 17

An interpreter does not produce object code
The translator translates and executes each line of code in turn
Advantages
Any errors present are highlighted immediately and easier to fix
They can run code still being developed
Disadvantages
The translation is not saved and therefor must be rerun each time the code is run
If a loop is present the code is translated and run many times
Individual runs are slower

Question 18

What is a compiler

Answer 18

A compiler translates source code into machine code. Once the code is translated it is stored and does not have to be translated again
Advantages
If no errors are found the source code does not need to be translated again
Disadvantages
If any syntax errors are present the program won’t run
The errors are harder to correct as they are not identified until the code is translated

Question 19

What is floating point representation

Answer 19

It is used for real numbers which are numbers with a decimal portion
Only the mantissa and exponent are stored, the base is implied saving storage space

Question 20

How are bit maps stored

Answer 20

Made up of small squares of colour (pixels)

Question 21

How are vector graphics stored

Answer 21

Each object in the picture is described mathematically as a list of attributes

Question 22

What is the processor

Answer 22

The processor is at the centre of all of the computers operations and deals with all the movements of data and any calculations to be carried out. Composed of the
Control unit
ALU
Registers