A processor has main three functional units- The Control unit, The Execution unit and The Bus management unit. The control unit accepts incoming instructions and data, decodes it and send to the execution unit. There it processes the task as of the instruction. The bus management unit manages the flow of incoming and outgoing data and information that links to the RAM.
Author: Kioskea’s Creative Commons, France Last update: 16 Oct 2008
RAM
Also known as Random Access Memory is the form of memory that offers access time for instructions. It’s a volatile memory- data can be wrote on it and read from it but only for a temporary period of time. It losses data when the computer shuts down or when the power losses. So when the computer shuts down the RAM memory will be send to a ROM or secondary hard disks. During a system crash the RAM may not get enough time to send the data stored in it to a safe place, hence the data is lost. This is why we lose the last changed settings or data after the crash.
RAM’s are of two types- SRAM (Static RAM) and DRAM (Dynamic RAM).
ROM
It stands for Read Only Memory. It’s a non-volatile form of memory. It will not lose data when the system power off. So data can be stored in it as long as it is needed.
Depending on the type of ROM data can be written or may not be able to write on it.
THE BIOS
It is a collection of software on a ROM chip, it is also a part of the Operating System. It is the Basic Input Output System which determines what a computer can do without accessing programs from the disk. The Bios contains the codes to control the keyboard, the monitor, the disk drives, serial communication etc.
As the BIOS is placed on the ROM it’s not affected by power failure, making possible the computer to boot itself than from an external sources like a CD. The Bios checks the default hardware configuration with the configuration data hence stable the system. So Bios is considered as the most important diagnostic tool available. It handles the input output flow of the computer data.
Author: Jupitermedia Corporation, New York
POWER SUPPLY
The PSU or the Power Supply Unit is a box in the CPU with a fan and a lot of cables. Its main job is to supply power to various system components in the right type and needed voltage. It accepts the electricity from the mains and converts it from AC to DC. It also eliminates spikes and surges, which is common in electrical items.
The features of PSU differ from according to PC. In some computers the AC power to the monitor is given by the PSU. There are two types of power supply units, external and internal. The external power supply unit provides ac current and the internal ones provide 5V or 12V of dc, which varies by the components.
FAN & HEAT SINK
Some motherboard components like hard drives, video cards, processor etc produce a lot of heat. This heat may affect the working of the chips close to these components, the computer becomes over heated and fails. To prevent this Heat Sinks and Fans are used. The heat sinks with large surface area absorb maximum heat, the fan then pulls out these hot air from the CPU.
Modern Pentium Processors becomes very hot and fails easily, so the heat sink in modern computers are moulded onto the processor chip using mercury based thermal grease. Thermal grease is a special kind of gel which helps to improve heat conductivity between metals.
HARD DRIVES & CONTROLLERS
Hard drive for a computer is the general term used for all the drives including CD, DVD and floppy drives. The device where hard drives are located is known as IDE devices which are controlled by an IDE controller. IDE stands for integrated drive electronics.
There are two types of IDE controller- Primary and the Secondary. Hard drives are attached to the primary controller. CD drives and other drives are connected to the secondary IDE controller.
PORTS & PERIPHERALS
The ports help to connect the peripherals to the CPU. There are two kinds of ports- Parallel and Serial port.
Peripherals are of 3 types- Input, Output & I/O device.
- Input device are devices through which user inputs data to the processor. Key board is an input device used to input information, mouse is used to input commands.
- Output device shows the results of the input data or the command.
- Input/Output device are the storage devices like a Ram or ROM.
SPECIALISED CARDS
They are the devices placed on the slots of the motherboard and connected to the buses to carry data. These slots are of three colors- the black slots are ISA slots which is connected to the buses that carry data at slower rate, the white slots are known as PCI slots which connects to the buses and have faster data transfer rate. The grey ones are the AGP slots used for Video cards. This slots have data transfer speed as same as of the processor speed.
Ref: BTEC National- Information Technology Practitioners Book 1 (2nd edition)
Author: Heinemann Publications
