Central processing unit
The Central processing unit (CPU) is the heart of a computer. The CPU is fabricated in the form of an integrated circuit called microprocessor . The CPU performs actual calculation, makes decisions and guides the machine in all its operations; it works closely with internet memory. Every CPU has three basic components, namely
1) Control Unit
2) Internal Memory
3) Arithmetic system
It works as manager for controlling the activities of the computer such as data transfer from one device to another. Internal memory is very small in size and is used to temporarily hold part of the data and instructions currently being processed. ALU performs arithmetic and logical operations on the data.
In addition to the internal memory, a computer has main memory. The main memory stores operating system, programme and data. The use of main memory for storage of programmes and data increases efficiency and processing speed of the computer. The results, which are generated after processing of data, are also stored in the main memory. This memory. This memory has the characteristics of Random Access Memory (RAM) . It is volatile which means that information stored in it is lost as soon as the computer is switched off.
The microprocessor chip is mounted on a circuit board, which is called motherboard the motherboard contain a memory chip and many others components to support various functions performed by the computer. These components are connected by control bus, address bus and data bus. Motherboard provider I/O slots for insertion of adaptor cards. The adaptor is an interface between the computer and a peripheral device . For example, the floppy disk drive is connected to the computer motherboard through an adaptor card. The adaptor card is connected to the computer motherboard through an adaptor card called floppy disk controller. Similarly the monitor, the printer and the hard disk are also connected through appropriate adaptor cards. In many cases, whenever a peripheral device is replaced with another one, the corresponding adaptor card is also required to be changed.
The number of operation carried out by the microprocessor depends upon it's clock speed and word length. Quartz crystal is used to generate electric clock pulses for the CPU. It is mounted on the motherboard. It produces millions of electric pulse each second to control 4tye timing of all operations of the processor and other peripheral. The speed of execution of instructions is directly related to the frequency of this clock . The frequency of the clock is measured in mega hertz (1MHz is 1 million cycle per second).
The word length of the internal register during the computation of data, a larger size of these registers allows a big chunk of data to be processed at one stroke, Therefore the speed of the processor is directly related to the word length. The larger the word length, the higher the speed.
The overall speed of processing also depends upon the data bus. The larger the size of the data bus, the greater the amount of information that can be pumped in or pumped out of the computer, the size of the data bus is the number of bits that it can handle at a time. CPU fetches data from the memory or devices through the data bus. The results generated by the CPU are sent to the memory or other devices through the data bus. In the beginning the personal computer had 8-bit data bus. Later on as the technology developed, 16 bit CPU were used in the PC. Nowadays computers have 32 bit and 64-bit processor chips
The number of operation carried out by the microprocessor depends upon it's clock speed and word length. Quartz crystal is used to generate electric clock pulses for the CPU. It is mounted on the motherboard. It produces millions of electric pulse each second to control 4tye timing of all operations of the processor and other peripheral. The speed of execution of instructions is directly related to the frequency of this clock . The frequency of the clock is measured in mega hertz (1MHz is 1 million cycle per second).
The word length of the internal register during the computation of data, a larger size of these registers allows a big chunk of data to be processed at one stroke, Therefore the speed of the processor is directly related to the word length. The larger the word length, the higher the speed.
The overall speed of processing also depends upon the data bus. The larger the size of the data bus, the greater the amount of information that can be pumped in or pumped out of the computer, the size of the data bus is the number of bits that it can handle at a time. CPU fetches data from the memory or devices through the data bus. The results generated by the CPU are sent to the memory or other devices through the data bus. In the beginning the personal computer had 8-bit data bus. Later on as the technology developed, 16 bit CPU were used in the PC. Nowadays computers have 32 bit and 64-bit processor chips
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