Computer Science

What is secondary storage

It is the memory in which the computer can store the data or instructions which are not currently in use

List the main types of secondary storage

Hard Disk Drive, Solid State Drive, Compact Disk, Flash/USB Drive

What are input devices

Devices that allows users to input data into the computer

What are output devices

Peripherals that receive data from the computer

What is primary storage

It is the memory in which the computer can store the data or instructions that are currently in use

What are the 2 main types of primary storage

RAM - Random Access Memory

ROM - Read-Only Memory

What is a processor

It is a special component that processes data and instructions to control other components within the computer

Examples of hardware

Processors, secondary storage, primary storage, input/output devices

What are the 2 main types of processors

Central Processing Unit (CPU)

Graphics Processing Unit (GPU)

List types of computer systems

Embedded and general purpose

What is a general purpose system

A system capable of performing many different tasks

Examples of general purpose sysytem

PCs, Macs, Smartphones

What is an embedded system

A system built into another device to support its operation

Examples of embedded system

Washing machines, digital cameras

Advantages of high level languages

• Makes it easier for us to program because they are human readable statements

• Can be run on may different types of hardware (portable)

Advantages of low level languages

• LLLs provide exact control over the central processing unit.

• LLLs need less translation, and often lead to faster code which is useful for computers with low specifications such as embedded systems.

What is a translator

A special software that converts source code into executable binary.

List the types of translators

Compilers, interpreters and assemblers

What is a compiler

It is a kind of translator that converts high level language to executable machine code in one go

Pros of compilers

1. They produce an executable program

2. They hide the source code from the end user

Cons of compilers

1. The compilation process can be very slow

What is an interpreter

It is a type of translator that converts high level language to executable machine code one line at a time

Pros of interpreters

1. It will stop as soon as they encounter an error

2. They are portable

Cons of interpreters

1. It is slower than a compiled program

2. They do not produce a compiled program file

What is an assembler

It is a type of software that converts assembly language into machine code

Pros of assemblers

1. It provides exact control over the hardware

2. it can be used on low specification machines

Cons of assemblers

1. It s very difficult to use

2. Needs deep technical knowledge of the CPU and memory

What is an assembly language

It is a type of low level language

What are transistors

They are electrical components made from semiconductor materials that can act as electrically- controlled switches

Uses of transistors

Used to temporarily store data e.g. primary storage, arranging into logic circuits

What are logic gates

A series of transistors connected together to give one or more outputs with each output being based on the input or combination of inputs supplied to it.

Examples of logic gates

AND, NOT, OR, NAND, NOR, XOR

What does the AND gate do

It will only output true if both of its inputs are true.

What does the OR gate do

It will output true if either or both of its inputs are true.

What does the NOT gate do

It takes one input and inverts it

What is the symbol for the AND operator

‘-’

What is the symbol for the OR operator

‘+’

What is the symbol for the NOT operator

Ā

What is an application software

A type of software that helps a user perform a given task.

Examples of application software

Word processors, web browsers and presentation software

What is a system software

It is a type of software that controls the hardware of the computer and the application software

What are the types of system software

OS, utility software, device drivers

What is an operating system (OS)

A type of system software that manages access to the hardware in the computer

List the purpose of an Operating system

Manages user interface (UI), manages I/O devices, manages memory, manages user authentication, manages distribution of CPU cycles, manages files.

What are device drivers

They are a type of system software that tells the OS how to use a piece of hardware

What is an utility software

A type of system software that performs maintenance tasks to make sure the operation of the system continues.

What are the 4 main types of utility software

Compression, backup. encryption and defragmentation

What is compression

The process of applying an algorithm to reduce space needed to represent a file or its contents

What is backup

The process of making copies of data that can be restored in an evet of data loss

What is encryption

The process designed to prevent unauthorized access to files by applying an algorithm to “scramble” data.

What is defragmentation

The process of improving hard disk performance by applying algorithm to recognize data

What are the 3 types of user interface

Graphical, Command Line and Window-Icon-Menu-Pointer

What is command line interface (CLI)

A type of user interface that controls the computer by texting commands using the keyboard

What is a window-icon-menu-pointer (WIMP)

The use of he use of Icons, Menus and a Pointer or cursor.

What is graphical user interface (GUI)

They are based on the WIMP paradigm or multi-touch interface

How are modern CPUs based (arranged)

They are based on Von Neumann architecture

What are the components of the Von Neumann architecture

ALU, CU and registers

What does the arithmetic and logic unit (ALU) do

It performs all the arithmetic and logic operations of the CPU e.g.

• plus, minus, times and division

• Comparisons of numbers

• Boolean operations

What does the control unit (CU) do

• Sends control signals to other parts of the CPU

• Executes program instructions by following the fetch-decode-execute cycle

What is the CU made up of

Made up of the clock and decoder

What does the clock in the control unit do

Coordinates the CPU’s activity

What does the decoder in the CU do

Decodes program instructions

What are registers

They are tiny amounts of super-quick memory within the computer

What does the registers do

• They are used to hold information needed for the CPU to work

• Each register holds a specific information

What are the types of registers

Memory address registers (MAR), program counter (PC), accumulator (ACC), memory data register (MDD)

What does the MAR do

Holds the address of the location in memory where data is to be stored or retrieved

What does the program counter do (PC)

Holds the memory location address of the next instruction to be performed by the CPU

What does the ACC do

Holds the result of calculations and operations performed by the ALU

What dos the MDR do

It holds the data that has been retrieved from or is about to be stored in the memory

What is the fetch-execute-cycle (FDE)

The process the processor follows to retrieve instructions and data from memory.

What does the fetch stage do

• The address of the next instruction to be processed is copied from the Program Counter (PC) to the Memory Address Register (MAR).

• The PC is incremented to point to the next instruction that will be needed when the cycle starts again.

• The instruction stored at the location held by the MAR is copied to the MDR.

What does the decode stage do

The CU decodes the instruction and sends control signals to the component within or outside the CPU that needs to act.

What does the execute stage do

The operation indicated by the instruction is performed buy the appropriate component

What are the factors affecting CPU performance

(Cores, cache size, clock speed,) - the main 3, cache type

What is a core

It is a processing unit within the CPU capable of processing instructions independently

How can a core help improve a CPU performance

Multiple cores allows a CPU to process multiple instructions at the same time

What is a cache

Small amount of RAM located on the CPU itself

How does cache help improve a CPU performance

More cache memory speeds up the processor

What does the CPU clock do

Sends a pulse at fixed intervals to trigger the next stage of the (FDE) cycle

How can a clock help improve a CPU performance

The higher the clock speed, the more pulses are sent per second so more instructions can be executed in the same amount of time

Features of RAM

1. More expensive per unit capacity than secondary storage

2. Any part of the memory can be accessed non-sequentially and quickly as any other part of the memory

3. It is much faster to access than secondary storage e.g. HDD

4. It is volatile

What is the meaning of volatile

It means it will loose its contents when power is lost

What is the meaning of non-volatile

It means it will keep its contents when power is lost

What are the 2 types of memory

Primary (main memory) and secondary storage

Features of ROM

1. It is non-volatile

2. It’s contents cannot be changed easily because it is often made from flash memory

3. It stores only small programs that boots up the computer

4. It is very fast to access

5. It is expensive

6. Tends to be very small

What is basic input output system (BIOS)

They are programs that starts up the computer

Examples of BIOS programs

1. Load an OS

2. Check the system for errors