Compter systems v2

Question 1

Define Hardware.

Answer 1

The physical components that make up a computer system. (e.g. motherboard)

Question 2

What is a computer system?

Answer 2

The hardware and software working together making up a computer, processing data and completing tasks, allowing users to perform specific tasks.

Question 3

Define Software.

Answer 3

The programs that run on a computer (e.g. utility software)

Question 4

Describe what systems software is vs. application software.

Answer 4

SYSTEMS SOFTWARE - The programs that manage/control computer hardware and application software (e.g. operating system).

APPLICATION SOFTWARE - The programs (launched from OS) which help the user perform specific tasks (e.g. word processors).

Question 5

Describe the roles of the operating system.

Answer 5

1. User interface - communicating with the user (sending and receiving instructions to and from applications and hardware).
2. **Memory management **- allocating memory addressed for processes/data.
3. Scheduling - scheduling CPU time between programs, allowing multiple to run.
4. File management
5. Device drivers - OS uses them to communicate with with peripherals (software that translates commands).
6. User management - Authentication, passwords, username.
7. (Peripheral) I/O device management - moving data to and from secondary storage.
8. application management

Question 6

What is Utility software?

Answer 6

Programs that keep the computer functioning efficiently (e.g. freeing storage space, removing viruses, backing up files).

Question 7

What are roles of Utility software?

Answer 7

1) Compression - reducing file size so it can be stores using less space/ transmitted quicker.
2) Defragmentation - Moving separate parts of a file physically together, to speed up disk access.
3) Backing up - Creating copies of files on the same disk, back up device or cloud
(Full Backup - copy of all files; Incremental backup - copy of files created or edited since last backup.)
4) Encryption - data scrambling to prevent unauthorised access of files/data. For secure storage/ secure transmission.

Question 8

Explain Von Neumann architecture.

Answer 8

Von Neumann architecture is a system where both data, instructions (+ programs) are stored in the same main memory. Refer to diagram.

Question 9

What are the main parts of the CPU?

Answer 9

• Control Unit
• ALU (Arithmetic logic unit)
• Clock
• Registers
• Buses

Question 10

Describe the roles of the ALU.

Answer 10

• Performing arithmetic operations ( + - x / )
• Performing relational operations ( < > = )
• Performing logical operations ( AND, NOT, OR)

Question 11

Describe the roles of the Control Unit.

Answer 11

• Managing execution of instructions (by coordination activates of other hardware).

e.g. sending signals to RAM to state whether data should be READ or WRITTEN to from memory.

Question 12

Describe the roles of the Clock.

Answer 12

• A signal that synchronises tasks (by synchronising all components of the CPU)
• 1 tick of the clock, 1 instructions is processed.
  (Clock speed measure in gigahertz)

Question 13

Describe the roles of the Registers.

Answer 13

• Small areas of memory that hold data and memory addresses used during fetch execute cycle.

Question 14

Describe the roles of the Buses.

Answer 14

Data Bus - moves data back and forth between CPU and memory.
Address Bus - transmits memory locations.
Control Bus - transmits commands to other components.

Question 15

Describe the factors that affect CPU performance.

Answer 15

1) Number of Cores
Core - a single unit comprising ALU and Control Unit, which can execute instructions.
(Overhead - time lost to organising which core will follow which instructions, minimal).

2) Clock Speed
Clock Speed - number of clock pulses per second, measured in gigahertz.

3) Cache Size
Cache: Stores copies of data/instructions from RAM which are access regularly.

4) Cache Type
L1,L2 or L3. L1 Smallest fastest, L3 largest, slowest.

Question 16

What is the Fetch-Execute cycle?

Answer 16

Fetch Execute Cycle - a continual sequence of tasks that result in instructions being fetched from main memory, decoded so that the CPU knows what to do, and execute (carried out).

Question 17

Describe and Explain the Fetch Stage in the Fetch-Execute Cycle.

Answer 17

1) There is 1 Clock Pulse.
2) A register (Program counter) contains the location of where the next instruction is to found.
3) The location (Address) is transmitted along the address bus to memory.
4) Memory responds by sending the contents of the address along the data bus back to processor.

Question 18

Describe and Explain the Decode Stage in the Fetch-Execute Cycle.

Answer 18

5) The Instruction is read by the control unit, which prepares the register for the type of data it will be storing.

Question 19

Describe and Explain the Execute Stage in the Fetch-Execute Cycle.

Answer 19

6) The instruction is carried out (performing operation, storing something in register etc.)
7) The Program counter is updated as the current instruction has been executed.

Question 20

What is an embedded system?

Answer 20

A dedicated system which is part of a larger system. They are computers built into other devices, like dishwashers, microwaves and TVs.

Question 21

What do embedded systems normally do?
What are the advantages of embedded systems?

Answer 21

• Embedded systems are often used as control systems. They monitor and control machinery in order to achieve a desired result.
• As they’re usually dedicated systems, and only serve one purpose, they are easier to design, cheaper to produce, and more efficient at doing their task than general purpose computers.

Question 22

What are the 2 types of programming languages?

Answer 22

High Level Languages - more understandable to humans than L.L. (python)
Low Level Languages - hard to understand for humans, easy to execute for computers (machine code, assembly language)

Question 23

What is a translator, and name the 3 types.

Answer 23

Translator - program that translates source code into machine code.

Assemblers: translates assembly language
Interpreters: translates and execute HL, one line at time
Compilers: translates HL programs, then executes in one go

Question 24

What is RAM memory?

Answer 24

• Random Access Memory, a form of volatile main memory in a computer.
• When a program is loaded from a computer’s hard disk, the data and instructions are loaded into RAM.

Question 25

What is ROM memory?

Answer 25

• Read Only Memory, non volatile (contains BIOS as an example).
• ROM memory stores data and instructions that will not need to be updated. content cannot be edited or deleted.

Question 26

What is cache memory?

Answer 26

Cache memory stores copies of data or instructions accessed regularly from RAM.

Question 27

What are the difference between RAM and ROM?

Answer 27

RAM:
Random Access Memory
Memory addresses can be read or written to
Increase the capacity, the PC’s overall speed will increase
Volatile (data is lost when power lost)

ROM:
Read only Memory
Memory addresses can only be read to
Non Volatile

Question 28

What is main memory?

Answer 28

Main storage directly accessible to the CPU (except cache and registers).

Question 29

What is secondary storage?

Answer 29

Secondary storage is non-volatile storage not directly accessible by CPU.

Question 30

How does optical storage work? (Including advantages and disadvantages).

Answer 30

• Read and Written to with a laser
• Optical disc spins to allow laser to read data from the correct location
• burned by laser to store values, 1 - land, 0 - pit

(+) 1 disc is very cheap; can’t accident overwrite data; portable; immune to magnetic fields
(-) vulnerable to scratches; low data capacity

Question 31

How does Magnetic Storage work? (Including advantages and disadvantages).

Answer 31

• They are round (but often put in rectangle housing)
• The surface is divided into tracks and sectors
• Disk will spin to allow the read-write head to access data in a specific segment
• In each sector, billions of magnetic particles (1) magnetised, (0) not.

(+) Cheapest storage/ Megabyte; more practical than multiple optical discs
(-) Slower access speed than SS; data is all in 1 device, can be lost, data can be lost near strong magnetic fields

Question 32

How does Solid State Storage work?

Answer 32

• They use electronic circuits to store data electronically
• sturdy and quiet (no moving parts)
• non volatile electrical circuits

(+) fastest access speed; no moving parts, harder to damage; very portable
(-) most expensive/Megabyte; limited number of times its written to.

Question 33

Define cloud storage.

Answer 33

Storage on remote computers, usually managed by other organisations. When a file is saved or loaded, and then transmitted across the internet, and multiple backups of the file exist around the world. It uses magnetic and SS storage.

Question 34

What are the advantages and disadvantages of cloud storage.

Answer 34

(+) Less likely to be damaged (data is stored remotely, in multiple physical locations)
(+) Capacity on your machine is freed up
(+) multiple people can access files at the same time
(+) can access data anywhere

(-) Cloud storage comes with a subscription fee
(-) It requires internet access and speed depends of Wifi speed.
(-) Hosting company could be hacked

Question 35

Order these in terms of data access speed:
Flash drive, RAM, Cache, Hard disk drive, registers, CD

Answer 35

Fastest:
Registers (MM)
Cache (MM)
RAM (MM)
Flash drive (SS)
Hard disk drive (magnetic)
CD (Optical)

Question 36

Order these in terms of capacity:
Hard disk drive, CD, Flash drive, DVD

Answer 36

Largest Capacity:
Hard disk drive (magnetic)
Flash drive (SS)
DVD (Optical)
CD (Optical)