Computing A451 Topic 2

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The CPU (Central Processor Unit)

The CPU is the brain of the computer.

Properties of the CPU:

  • Cores
  • Fetch-code-execute
  • Control Unit
  • Clock Speed
  • Immediate Access Store
  • ALU (Arithmetic Logic Unit)
  • Cache Memory

Purpose of the CPU:

The main purpose of the CPU is to process data. It will perform searches, sort data, make calculations and make decisions.

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Binary and Logic Gates

Computer systems can only understand ON and OFF instructions. These are represented by the value of 1 and 0. This is known as binary.

To make a decision computer systems will compare bits using a certain gate in a circuit. These are called logic gates. There are three main gates: AND, NOT and OR.

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RAM (Random Access Memory)

  • Holds the instructions whereas the processor carries out them.
  • More RAM means you can hold more nstructions.
  • Filled RAM can cause computers to freeze or crash
  • RAM is volatile. Deleted when the computer is not on.
  • GB

ROM (Read Only Memory)

  • Small chip in the motherboard that stores boot up instructions
  • Check all hardware that is installed
  • ROM is non-volatle. Instructions remain even when the computer is off.
  • It cannot be changed by the user.
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Virtual Memory

Virtual memory acts as extra RAM for your computer.

If you are doing a lot of multitasking it will take up a lot of RAM, and if it is filled programmes will no longer open.

Instead of not allowing you to open more programmes the computer takes some of the RAM instructions and copies them to the hard drive, giving us more RAM.

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Cache Memory

Cache Memory is similar to RAM but it is found in the processor.

The CPU can access the Cache Memory faster than RAM and this is why we store some data and instructions in there.

The Cache stores instructions and data that we constantly need to access by certain software. This can in some cases improve the overall speed of the programme.

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Flash Memory

Flash Memory is non-volatile and comes in a solid state. This means data is kept when it has no power and no moving parts.

A USB, memory card, tablet storage, mobile phone storage and video game storage all use Flash Memory.

Flash Memory offers much faster access speed than a traditional hard drive and is why solid state drives are on the rise.

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Input and Output Devices

Input - An input device is any hardware that can enter data into a computer.

  • Webcam
  • Barcode Reader
  • Scanner

Output - An output device is any hardware that can display or output data that is processed or has been stored on a computer.

  • Monitor
  • Speakers
  • Printer
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Secondary Storage

Secondary Storage is the term used for data that is stored on a storage device.

Considerations of Data Storage:

  • Capacity
  • Speed
  • Portability
  • Durability
  • Reliability

Ways to store data:

  • Hard Drive
  • Optical
  • Magnetic Tape
  • Flash
  • Network
  • Online
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