basic components, memory
TRANSCRIPT
CXC Information Technology
Unit One – Basic Computer components
Basic computer components
Every computer, regardless of size, shape or function work in basically the same way
Input Process Output
Types of computers
Supercomputers Desktop Computers Notebook (laptop) Netbook Handhelds Tablet computers E-book Readers
Basic components CPU (Brain of the computer)
ALU – Arithmetic and Logic Unit Control Unit
Main memory RAM or ROM
Secondary memory (storage) Diskettes, CD-R’s etc.
Peripheral devices (input and output) Any external device attached
Information flow in a computer
INPUT
MAIN MEMORY
SECONDARY MEMORY
CPU:
ALU
Control unit
OUTPUT
KEYBOARDMOUSE
JOYSTICKWEBCAM
MICROPHONE
MONITORPROJECTORSPEAKERS
HEADPHONES
DISKETTECD
DVDFLASH DRIVE
Arithmetic and Logic Unit (ALU)
This is the part of the CPU which is responsible for all mathematical and logic functions. It carries out all calculations and makes any decisions which the computer needs.
Control Unit
This is the part of the CPU which is responsible for directing all instructions going to the CPU. It tells the instructions when and for how long they can have access to the CPU. The control unit is like a traffic warden, directing and controlling the flow of data.
Memory
A computer’s memory is either main (primary) or secondary (backing storage).
Main memory is where all the data needed by the CPU to carry out instructions is stored.
Secondary memory provides more space for storing data (diskettes, CD-Rs etc.)
Main memory
ROM (Read Only Memory)This memory can only be read from. It is non volatile (data remains even though
power is turned off) ROM contains the instructions needed for the
computer to “boot” up properly.
Main memory
RAM (Random Access Memory)This memory can be read from and written
to. It is volatile (when power is turned off, all
information is lost). Instructions needed by the CPU while it is
working are stored in RAM.The more RAM, the faster the processing
Main memory – Other types of ROM PROM (Programmable Read Only Memory)
This memory can only be reprogrammed ONCE. EPROM (Erasable Programmable Read Only
Memory) This memory can be reprogrammed more than once.
It must however be reset to its original state.
RAM vs. ROM
ROM works when the computer is booting up
RAM kicks in when the computer has started. The CPU uses RAM
Secondary storage is used to save data for later.
Units of memory
Bit – The smallest unit of storage in memory
Byte – a collection of bits (7 or 8) Kilobyte – 1024 bytes (210) Megabyte – 1024 kilobytes Gigabyte – 1024 megabytes
1 bit1 bit
8 bits = 1 byte8 bits = 1 byte