What is Computer Architecture ?
A Computer is a fast electronic calculating machine that accepts digitized information from the user, processes it according to a sequence of instructions stored in the memory and provides the processed information to the user.
In computer science, computer architecture is a set of discipline that describe the part of computer system and their relation.
Personal Computers are the most widely used computers which have applications used in everyday activity of the modern world.
Example like Middle class Indian homes, cyber cafes, shopping malls, business institutions etc.
This is slightly different form the regular PC in respect that is has evolved from the mini computers. Originally used for engineering, graphics and such other non-personal work or technical work, workstation computers were designed for the purpose of singular interaction of computer with one persona at a time.
Components of Computer
A computer mainly consists of four man components as follows :
- Input Unit
- Output Unit
- Central Processing Unit
- Memory Unit
The computer accepts coded information through input unit by the user. It is a device that is used to give required information to the computer.
Example like, Keyboard, Mouse etc.
The output unit sends the processed results to the user. It is mainly used to display the desired result to the user as per input instruction.
Example like, Monitor, printer and plotter etc.
Central Processing Unit (CPU)
The central processing unit consists set of registers, arithmetic and control circuits, which together interpret and execute instruction in assembly language.
Central processing unit is often called the brain of computer.
The CPU is single integrated circuit chip and also known as microprocessor.
A CPU controls all the internal and external devices and performs arithmetic and logic operations.
A program counter is a register in a computer processor that contains the address(location) of the CPU instruction being executed at the current time.
The CPU consists of three main sub-systems, Arithmetic Logic Unit(ALU), Control Unit(CU) and Registers
- Arithmetic Logic Unit(ALU)
It is used to perform all arithmetic calculations (addition, subtraction, multiplication and division) and logical calculations (AND, OR etc.)
A register is a small amount of very fast memory that is built into the CPU in order to speed up its operations by providing quick access to commonly used values.
- Program Counter – PC keeps the address of the next instruction
- Memory Address Register – MAR holds the address of memory location
- Memory Data Register (MDR) – It stores the data to be stored in the computer storage (e.g RAM) or the data refer fetch form the computer storage
- Current Instruction Register – CIR stores instruction that is currently being executed.
- Accumulator – used for storing data and for carrying out arithmetic and logic manipulations.
- Control Unit
It is also known as nerve center. Control unit coordinates with the input and output devices of a computer. It directs the computer to carry out stored program instructions by communicating with the ALU and the registers.
- Memory Unit
This unit is responsible to store programs or data on a temporary or permanent basis. It has primary memory and secondary memory.
The input data which is to be processed is brought into main memory before processing. The needed instruction for processing and any kind of intermediate results are also stored in primary memory. Together with these, the final output is also stored in primary memory before transferring it to the output unit. Secondary memory is used to permanently stores data, programs and output. This unit does not deal directly with CPU.