Lecture 2

Question 1

What is hardware?

Answer 1

Hardware: covers all the parts of the computer that you can physically touch.
E.g. Keyboard

Question 2

What is a bus?

Answer 2

A ‘bus’ is a set of wires or copper tracks that are built into the motherboard
External buses such as USB can transfer data in and out of the computer
The bus system determines the size of each memory location and it also determines how much memory can be installed in the system.

Question 3

Data bus?

Answer 3

It is a bi-directional bus that carries data between the processor and memory

Question 4

Address bus?

Answer 4

Carries the address of the memory location being read from or written to

Question 5

Control bus?

Answer 5

Carries signals that control the operation of each device

Question 6

What is the control unit?

Answer 6

This is the part of the central processor unit (CPU) which manages the execution of instructions.
The control unit fetches each instruction in sequence, decodes and synchronises it before executing it by sending control signals to other parts of the computer.

Question 7

What is the ALU?

Answer 7

This is the part of the CPU where data is processed and manipulated. The Arithmetic Logic Unit performs logic, shift and arithmetic operations on data.
Logic-NOT, AND, OR
Shift-shift bit pattern to left or right
Arithmetic-add, times,subtract

Question 8

What are registers?

Answer 8

A small number of read/write memory cells that operate at very high speed.
Part of the ALU.
Holds the operands of an operation and on completion holds the result of the operation.
Addressed more quickly than regular memory cells

Question 9

what is a byte?

Answer 9

If a memory location contains 8 binary digits (bits) it is known as a byte

Question 10

What is ROM?

Answer 10

ROM cannot be changed by the processor, but only read by it.
When the computer is turned off the contents of ROM are maintained - known as non-volatile memory.
ROM is used for:
Storing the bootstrap program that starts the computer
Store fixed data associated with the computer system
Sometimes stores programs that remain in the computer at all times.

Question 11

What is RAM?

Answer 11

Memory which holds data loaded from the backing store – data that the computer is to process, screen display etc.
It can be written to i.e. read/write memory
Lost when the computer is turned off -known as volatile memory
RAM is used for:
Storing programs that are being executed
Store data required for immediate use
As buffers for external storage devices

Question 12

what is Cache memory?

Answer 12

High speed memory
Part of the processor or a special high speed cache memory chip
Used to speed up the execution of computer programs
Cache memory is faster than RAM and ROM but slower to access than a register
The following can be stored in a cache:
Program instructions that are executed many times
Regularly used data
Virtual memory page tables
Pipelining

Question 13

what is the Machine clock?

Answer 13

An electronic device that produces a pulse of electricity at regular intervals.
A computer runs on a clock – a 2.5 GHz machine is running at 2.5 thousand million cycles per second. Each cycle is a clock pulse. The faster the clock, the more instructions per second.
Used to synchronise the computer system
Normally connected to the processor passing on synchronising signals through the control bus.
The complexity of the instructions affects the speed of processing.

Question 14

Improving performance:

Number of cores

Answer 14

A single processor can only run 1 instruction at a time.
To get beyond this you need an additional processor.
This allows more than one instruction to be run and increases the speed of the computer.
Programs and computers have to be written to make use of the second processor

Question 15

Improving performance:

Bus speed

Answer 15

The speed of the computer is also determined by how fast the data can travel. Data travels down buses
Increasing the speed of the bus decreases the waiting time and increases the speed. The speed of the bus is determined by the clock speed

Question 16

Improving performance:

RAM

Answer 16

The more RAM you have, the more instructions you can store without having to access the disk which is slow. It decreases disk thrashing
Cache memory is even faster and with more of it, the machine runs faster still

Question 17

Improving performance:

Dedicated Processing Devices

Answer 17

Instead of using the processor to do all the processing you can use specialist processors to take some of the load and thus speed up the machine. These include sound and graphics processors

Question 18

Making a Machine Run Faster

Software options

Answer 18

Memory Optimiser:
Better use of memory
Replace programs with up-to-date ones:
Make better use of memory and resources
Patch software / run anti virus / anti spyware:
Remove programs using resources
Defragment Hard Drive:
Increases BUS speed
Remove Unused Programs:
Frees up hard drive space
Large swap file

Question 19

Magnetic storage devices

Answer 19

Create magnetised areas on magnetic media to represent the data. Areas of magnetised and non-magnetised are detected by the computer
e.g.s are hard disks, floppy disks, magnetic tape

Question 20

Optical storage devices

Answer 20

Uses lasers to burn spots on optical media
A light is used to read the spots and interpret them as data
e.g.s CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R and DVD-RW

Question 21

Memory sticks

Answer 21

Use semi-conductor memory called flash memory

Similar to memory chips in the computer but hold data permanently

Question 22

What is an input device

Answer 22

Allows data to be entered onto a computer

Question 23

What is an output device?

Answer 23

Allows data to be retrieved from a computer after processing

Question 24

What is the Program Counter?

Answer 24

PC-keeps track of the memory location of the line of machine code being executed
Contains the address of the next instruction that is needed to be fetched/carried out.