Main parts of the system Unit - Types of system unit ?

 Types of system unit

1) The parts of processing unit (CPU) :

The part of the computer that does all the work, all the thinking and all the processing is called the processor or central processing unit (CPU). CPU is brain of the computer. It is linked with the input units and output units to form the computer system. In terms of computing power, the CPU is the is the most important component of a computer system. Om personal computer (PC) and small workstation, the CPU is housed in a single chip called a microprocessor or microchip. Following are the various type of CPU chips :

• Pentium AMD
• Pentium Pro
• Pentium 3
• Pentium 4
• AMD DURON
• Athlon 
• Cyrix 
• Intel Celeron 

The processing speed of CPU is measured in terms of MHz (Mega hurtz) and GHz (giga hurtz). The fastest one in the market is Pentium 4. Central processing unit consists of following three basic parts :

Main memory unit :

It is a storage section of computer. It stores the instruction and data that will be used the computation. Two types of memory units namely internal or primary memory and secondary or auxiliary memory are attached with the processing unit. Internal memory is that memory where the instruction or data has to be locked during execution. In other words, primary memory stores data or a pen drive instruction and analyse or solve them. It has strong capacity of memory as well as high recalling capacity. Auxillary memory is that which stores data or instruction permanently through floppy, CD Hard disc (HD) and pen drive. The storage capacity of memory is expressed in MB or in GB.

Control Unit :

This unit of computer controls the sequence of operation and the tasks performed by all the other units. It gives commands to input devices to transfer data to memory and also direct the output to be transferred to the output devices. In addition, it sends signals from the memory to be artithmatic and logical unit for computation and logical tasks and direct transfer of calculated data and instruction back to main memory.

Arithmetic and logical unit : 

Any processing tasks that are performed by a computer are done in the arithmatic and logical unit. Arithmatic unit performs all the computational tasks like addition, division, substraction, multiplication etc. And logic unit perform all the logical tasks and decision in a process. 

2) Motherboard : 

The motherboard is the flat circuit board on which fibre like structures of metal connecting pins are mounted. These fibre like structures of metal are called 'Bus'. The motherboard is the main circuit board of a computer on which the processor, video card, IDE hard drive etc. are all plugged into the various slots and connectors. Thus, we can say that all the functions of the computer are controlled by this mother board.

RAM Chip Slots : 

These slots are meant to expand the computer's memory by adding RAM chips. 

ROM : 

It is a silicon chip on motherboard on which instructions are burned at the time of manufacture. When computer is switched on, instruction stored is automatically initiated and after switching it off instruction do not get lost.

Expensive slot : 

It is a long narrow connector which allow us to plug in expansion card like network card, sound card etc. 

Some other parts of system unit are : Sound card, video card, RAM, Timer and power supply.