A computer system is a basic and functional computer which includes all the hardwares and softwares which are required to make it functional for the user. It is an electronic device which accepts the data as input, process the data in pre-determined way and then communicate the result as output on the screen.
CPU which stands for Central Processing Unit is the brain of the computer. It is an electronic circuit within a computer that executes instructions that make up a computer program. Various blocks of CPU are-
- It carries out the operations of arithmetic and logical expressions.
- Timing and Control Unit controls the entire operation being performed on the computer system.
- Register is a very small amount of very fast memory that is built in the CPU in order to store the current data and instructions which are being performed by the CPU.
- Memory unit is the storage unit of the computer system which is used to store the program statement and data.
- Input and Output unit sends and receives to data to display it to user.
Characteristics of Computer System :
- Size of Data Bus –
It defines the number of bits that can be transferred through the data bus. It is also known as the width of data bus. Data bus is bidirectional because micro-processor can read data from memory or write data to memory.
- Size of Address Bus –
The size of address bus determines the capacity of CPU or micro-processor to identify different memory locations.
Chip Size- 2(raised power R) * N Address Bus- 2(raised power R)
Address bus is unidirectional because the micro-processor is addressing a specific memory location. No outside devices cannot write into micro-processors.
- Word-length –
It is the amount of data that can be processed by CPU and micro-processor at a time. It depends on the data bus, register, ALU etc. For example, 8-bit processor can process 8 bit data at a time. A processor with larger word length can process data at a time with fastest speed as compared to processor with shorter word length.
- Capability –
It depends upon the number of instructions a micro-processor have and the flexibility provided by each instruction.
- Instruction Set –
It is the total number of instructions that a micro-processor can understand.
- Band-Width –
It is the number of bits processed in a single instructions.
- Data Types –
There are various types of data formats that can be handled by CPU or micro-processor such as binary, BCD, ASCII, Sign and Unsigned numbers.
- Input-Output Addressing capability –
It depends upon the input-output addresses provided by input-output instruction.
- Clock Speed –
The clock speed finds out the number of operations per second, the processor can perform. The CPU required a fix number of clock cycles to execute each instruction. The faster the clock, then CPU execute more instructions per second. It is expressed in MHz or GHz.
1 MHz= 1 million cycles per second 1 GHz= 1 billion cycles per second
Machine Cycle Clock Cycle or T-State Opcode Fetch 4T Memory Read 3T Memory Write 3T Input Output Read 3T Input Output Write 3T
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