Year 10 - Systems Architecture - Gcse Computer Science

Front 1

CPU Purpose

Back 1

To execute / run programs, to coordinate and manage the hardware resources.

Front 2

ALU Operations

Back 2

Simple arithmetic operations, Logic (comparison) operations

Front 3

Stored Program Concept

Back 3

Both the program and the data are stored together in the same memory. Von Neumann Architecture

Front 4

Control Unit

Back 4

Co-ordinates and controls the entire operations carried out by a computer.

It monitors hardware and the input and outputs and the flow of data in the CPU.

Front 5

Program counter

Back 5

Special purpose register that holds the address of the next instruction to be executed

Front 6

Accumulator

Back 6

Arithmetic and logic results are temporarily stored here

Front 7

Register

Back 7

A special fast memory location in the CPU.

Used to store instructions and small amounts of data.

Front 8

Memory Data Register

Back 8

Holds the actual data copied from RAM, ready for the CPU to process it

Front 9

Memory Address Register

Back 9

Holds the memory location of data that needs to be accessed from RAM.

Front 10

Current Instruction Register

Back 10

stores the instruction currently being executed or decoded

Front 11

Clock Speed

Back 11

Number of Fetch, Decode, Execute cycles per second. (Measured in Hertz)

Front 12

Clock speed effect

Back 12

The higher the speed (Hz), the more instructions the CPU will be able to carry out per second.

Front 13

Multi-core processors

Back 13

Two or more processors linked together on a single chip.

twice the power but does not always perform twice as fast, because the software may not be able to take full advantage of both processors.

If the computer is running a single program, it is not necessarily any faster, since instructions have to be carried out in sequence

Front 14

Cache

Back 14

small amount of very fast, expensive memory in the CPU

Front 15

Cache effect

Back 15

The data used most often by the CPU is held in cache so is instantly available.

Avoids having to travel to RAM which will take more time.

If you have a “while” loop in a program, for example, having all the instructions in the loop in cache speeds up execution

Front 16

Level 1 cache

Back 16

Cache memory that is extremely fast but small (between 2-64KB),

located very close to the processor

Front 17

Level 2 cache

Back 17

Cache memory that is fairly close to the processor,

fairly fast and medium-sized (256KB-2MB)

Front 18

Fetch

Back 18

causes the next instruction and any data involved to be taken from main memory

Front 19

Decode

Back 19

Interprets what the instruction means

Front 20

Execute

Back 20

carries out the instruction

Front 21

Embedded computer

Back 21

A special-purpose computer system.which is built into the hardware

and cannot be changed without replacing the hardware in which it is embedded

Without embedded systems, a digital device would not be able to perform specific functions

Front 22

Embedded computer uses

Back 22

Cars, Microwaves, dishwashers etc

Front 23

Dual core effect

Back 23

Allows 2 processes to execute instructions at the same time

More cores will improve performance in some circumstances but the computer system may not always be able to take advantage of more than one core e.g. multitasking

Front 24

MAR

Back 24

Memory Address Register

Holds the address of the instruction/data currently being used

Front 25

MDR

Back 25

Memory Data Register

Stores the actual instruction/data that is currently being used

Front 26

Fetch-Decode-Execute cycle

Back 26

The Processor fetches the next instruction to be executed from memory

whose address it looks up from the Program Counter

The Program counter is updated

The instruction contains the opcode and the data or address of the data

The instruction is decoded

The instruction is executed

And the cycle begins again.

Front 27

ROM

Back 27

Non-volatile memory that holds crucial information

such as the boot program thats instructs the CPU how to load the Operating system from the drive into RAM

READ ONLY

Can hold programs in embedded systems.

Front 28

RAM

Back 28

Store of currently running data and program instructions so that they can be retrieved quickly by the CPU

The Operating System / or the part of the Operating System currently in use.

The programs / software currently in use.

The data in use by those programs.

Any clipboard data

READ and WRITE

Front 29

Volatile

Back 29

Requires power to maintain the data stored within it.

Front 30

Virtual Memory

Back 30

Combines your computers RAM with temporary space on your hard disk when RAM runs out.

Avoids closing programs down.

Front 31

Virtual Memory disadvantage

Back 31

read/write speed of a hard drive is much slower than RAM

Front 32

Motherboard

Back 32

Central printed circuit board that holds the different computer components

Front 33

Flash storage

Back 33

SSDs, USB drives and SD cards (derived from solid-state storage)

Front 34

Input Device

Back 34

Any hardware device used to enter data into a computer system for processing

Front 35

Output Device

Back 35

Any hardware device used to present processed information to users

Front 36

Secondary storage

Back 36

Non-volatile method for storing large amounts of data for long term use

Needed because RAM is volatile and loses data once ther eis no power

e.g. hard drives, flash storage, CDs, USB sticks etc

Front 37

Optical

Back 37

involves the use of lasers to read and write data, e.g. CD, DVD

Front 38

Magnetic

Back 38

Mechanical parts move over the disks surface to read and write data magnetically

Traditional hard drive

Front 39

Solid State

Back 39

Data is recorded onto solid memory chips without any moving parts

e.g. SSDs (Solid state drives)

Front 40

Actuator

Back 40

Mechanical device that is controlled by computers

e.g. robotic arm, motor

Front 41

Magnetic advantages

Back 41

Cheap per GB

vast storage capability possible

fast write speed

Front 42

Magnetic disadvantages

Back 42

Lots of mechanical parts

durability an issue, sealed unit due to disk head and platter precision

not very portable

Front 43

Optical Advantages

Back 43

Cheap

very easily portable

takes up little space physically

Front 44

Optical disadvantages

Back 44

Less storage capacity compared to other types.

Easily damaged / scratched, requires a CD reader

Slow write speeds

Front 45

SSDs advantages

Back 45

Highly durable

no moving parts

very fast read/write speeds

no noisy fan

faster start up times

Front 46

SSDs disadvantages

Back 46

Expensive at present

less storage capacity / physical size than traditional hard disks

Front 47

How flash memory works

Back 47

Large electric current used to force electrons through a barrier and trap them on the other side.

They remain on the other side until “flashed” with a new current, hence the name

Front 48

Flash memory

Back 48

Low cost
portable
no moving parts
durable
Used for Cameras, mobile phones, USB sticks etc