Essentials 1

The computer

Foundation

Microprocessor

A microprocessor is also known as the Central Processing Unit (CPU). All the main calculations a computer makes are done using the processor. The processor is built onto a single chip.

Chip

This is the common name for an integrated circuit. It is small and usually made of silicon. It is used to send electronic signals.

Main memory

A running program is stored along with its data in the main memory of the computer.

Main memory is divided up into storage locations each with its own address.

A single storage location can hold one or more bytes of information.

RAM and ROM

There are two different types of memory: RAM and ROM

• RAM or Random Access Memory is volatile. This means that when the computer is switched off all the contents of the RAM are lost
• ROM or Read Only Memory retains all of its information even when the computer is switched off

Backing storage

Backing storage is used for permanent storage of programs and data.

Hard disks and USB flash drives are common forms of backing storage.

Magnetic tapes are used in large commercial organisations to store long term data. Backup copies are often held on tape.

For more information on backing storage, read the revision bite on Current backing storage devices.

Types of computer

Desktop

This type of computer tends to be in one location, e.g. on a desk, in a workplace. They usually have more memory, larger hard disks, better graphics and larger screens than most laptops or notebooks.

Laptops and notebooks

Laptop computers use an LCD/TFT screen, a keyboard and all other input and output devices in the base. They typically use a track pad or a raised button to control the pointer on the screen instead of a mouse. They are battery operated, with rechargeable power packs.

Palmtop

A palmtop computer is small enough to be held in one hand while it is being used. For this reason a palmtop computer is also called a handheld computer or a personal digital assistant (PDA).

They have:

• an LCD screen
• limited processing power
• main memory
• backing storage
• rechargable batteries

Palmtop computers are frequently used in business for:

• keeping schedule calendars
• address book storage and retrieval
• note taking
• doing calculations
• exchanging email and retrieving information from the internet (using a modem).

A microphone is often provided for voice recording.

Information can be input using an on-screen keyboard or by using a stylus on a touch sensitive screen.

Video clip - More PC power for less space

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Source: http://www.bbc.co.uk/bitesize/standard/computing/computer_systems/hardware/revision/1/