Computer system

Question 1

What is a computer?

Answer 1

• a machine that processes data

Question 2

Hardware

Answer 2

• physical component of a computer system

Question 3

Embedded System

Answer 3

• a computer system built into a device

Question 4

Control Unit

Answer 4

• controls the flow of data in and out of the CPU

Question 5

CPU

Answer 5

• processes instructions and data

Question 6

Registers

Answer 6

Examples:

• program counter
• accumulator register
• memory address register
• memory data register
• store data before its needed by CPU to be read to, written to, deleted or moved to another area

Question 7

Accumulator Logic Unit

Answer 7

• stores results of logic calculations and preforms division, multiplications, addition and subtraction

Question 8

Cache

Answer 8

• small memory store that contains frequently used data for faster access
• there are 3 levels ; higher level = lower capacity and faster access speed

Question 9

Fetch Decode Execute cycle

Answer 9

1 - copy the memory address from the program counter to the memory address register
2 - copy the instruction form memory address register to the memory data register
3 - program counter is incremented (increased) to point to the next data address instruction
4 - the instruction is decoded in the control unit and prepares for the next step
5 - the instruction is carried out

Question 10

Volatile

Answer 10

• data/ files that are deleted when device is switched off/ temporary

Question 11

Non Volatile

Answer 11

• data/ files that are not deleted when device is turned off/ permanent

Question 12

Random access memory

Answer 12

• stores data from in use program

- can be read and written to

Question 13

Read only memory

Answer 13

• stores data required for programs to run

- can only be read to

Question 14

Random Access Memory

Answer 14

• volatile
• stores data, files and programs when they’re in use
• can be read and written to

Question 15

Read Only Memory

Answer 15

• non volatile
• contains the BIOS that allows a device to boot up
• when the computer is turned on the CPU reads instructions from ROM to do self checks and set up the computer

Question 16

Virtual Memory

Answer 16

• used when RAM is full or low on storage
• its has slower access speed and lower capacity than RAM
• data is moved from VM back to RAM when it needs to be read

Question 17

Clock speed

Answer 17

• number of instructions that can be carried out by CPU per second
• measure in Hz/GHz; 1GHz = 1 billion instructions per second

Question 18

Cores

Answer 18

• A core is a section of the CPU that independently carries out instructions
• more instructions = faster access

Question 19

Primary Storage

Answer 19

• mostly volatile
• areas that can be accessed by the CPU very quickly
• stores data from in use programs
• ROM, cache, RAM and CPU registers
• fastest read and write speeds

Question 20

Secondary Storage

Answer 20

• non volatile
• where all data (operating systems, applications and user files) are stored when not in use
• includes hard disk drives, solid state drives, CDs and SD cards
• read and write speeds are slower compared to primary storage

Question 21

Tertiary Storage

Answer 21

• non volatile
• used for storing data long term
• mainly used for archives and backups for large amounts of data

Question 22

Hard Disk Drive

Answer 22

• traditional internal storage in PCs and laptops
• made up of a stack of magnetised metal disks
• data is stored magnetically in small areas called sectors, within circular tracks
• read and write heads on a moving arm are used to locate sectors
• portable HDDs are popular for backing up and transporting large amounts of data

Question 23

Summary of secondary storage

Answer 23

slowest - fastest:
- optical, memory card, magnetic tape, HDD, SSD

cheapest - most expensive:
- magnetic tape, optical disc, HDD, memory card, SSD

lowest capacity - highest capacity:
- optical disc, memory cards, SSD, HDD, magnetic tape