Computing mock prep

A computer system is a collection of hardware & software to produce a coded solution.

A computer must be able to Output , input & process.

Input devices include : Touch screen , a mouse , keyboards , Microphones , Foot mice & webcams.

A processing device is: Sounds cards & graphics cards.

Out put devices include : Printers , speakers & monitors.

Computer systems are important to the modern world because Communicate and work with people worldwide. Save lives (eg 999 system). Improve quality of life (eg bionics). Allow secure data access. Better manufacturing .

Define the term computer system

In computing relaiability is How dependable a computer system is to carry out a job you have entrusted it with .

A general computer system is A computer system that can load and operate with various apps. E.g a laptop/desktop.

A dedicated computer system is Specially produced system that have one purpose. E.g. ticket vending machine.

A control computer system is Computer systems that control machinery. Their output is read by another machine, rather than a human.

An embeded system is a computer system which is part of a larger system.

Examples of embeded systems are ; Digital watches, satnavs, cameras, MP3 players, traffic lights and controllers of machinery.

An expert computer system is Computer systems that are designed to behave like human experts in a particular field.

A computer system needs to be reliable as it has the ability to save lives. It could be the difference between life an death. E.g. ATC and medical situations.

Data integrity is Data being accurate and consistent throughout its life and reflecting what it means in the real world.

Data integrity can be comprimised by Human error, viruses, bugs in code, hardware malfunctions and natural disasters.

Software often has errors after being relased because Software is complex, testing is expensive, testing is time consuming.

De facto standards are They ensure some things are the same across computer systems so they can be used by everyone. E.g. QWERTY keyboards.

De jure standards are Standards that must be adhered to BY LAW. They are universally accepted. E.g. ASCII and PDF .

Propietary standards are They are decided by the company and ensure all their products work seamlessly together.

Industry standards are Standards set by recognised non-commercial organisation E.g. ANSI.

Open standards are not dominated by any one particular group and are produced collaboratively so they can be used across many apps and pieces of hardware.

Examples of open standards are ;HTML, HTTP, WAP & SQL.

Energy can be saved in a computer system by ; Automatic standby, solid state storage (doesn't rotate) & modern screens that are more efficient.

Computers can be bad for the enviromeny because they Contain toxins (cadmium etc), need electricity to run which usually means fossil fuels have been burned.

The cpu uses the cycle Fetch - decode - execute.

The thing determined by the CPU clock speed is the speed of the F-D-E cycle. It is measured in cycles per second (Hz). It is usually measured in GHz (billion of Hz).

The boot sequence is a pattern of processes that contain all the information needed to get the computer up and running.

The internet is An international network of computers.

The advantage of having Multiple processing cores is that more data is processed simultaneously.

The disadvantage of having multiple processing cores is that A more complicated operating system is required.

Cache memory is Memory that is quickly and easily accessed by the CPU.

Ram is Volatile.

Volatile is when things are lost when a computer is turned off.

Ram is bigger than ROM

What is meant by volatile memory?

Two things stored in Ram is the OS & Data currently in use.

One thing stored in ROM is The boot sequence .

Virtual memory is Part of the hard drive that is an extension to RAM .

When you increase the amount of RAM the amount of virtual memory decreases but the performance of the computer increases.

Flash memory is A type of ROM that can be rewritten. It can be portable.

A not logic gate changes the input to the opposite such as input 1 changed to 0.

To get a high output in an and gate 2 (both). It must be 1 1. 0 0 will produce an output of 0 .

An or gate is a logical operation which gives the value one if at least one operand has the value one, and otherwise gives a value of zero.

To get a high input in an or gate it must be 1 or both.

Magnetic memory is Memory that uses a magnetised field and possibly polarized elemental ions.

3 advantages of Magnetic memory hard disk includes ; Reliable, high capacity, low cost .

4 main considerations when selecting a type of storage includes ; Capacity, speed, portability, durability, reliability.

Secondary storage is Memory used to store data after the computer has been switched off.

Primary storage is; Volatile memory - includes RAM

System software controles Hardware.

Application software soes the jobs users dont want to do.

Ulility software is Limited functionality but is used maintain a computer system. .

GUI is A graphical user interface is easy to understand and uses recognisable icons.

Virtual memory is used for When excess jobs (jobs that won't fit in the main memory) are held in virtual memory.

Jobs of an operating system includes ; Issues error messages, manages memory, maintains security and access rights of specific users, deals with errors, deals with user inputs.

What are viruses?