1. What do mean by computer architecture? Describe each functional components of computer architecture with typical diagram.
When referring to computers, architecture or computer architecture is the overall design and setup of the computer. This includes where connections and parts of the computer are to be placed, how each of components operate with each other, dimensions, etc.
It is a framework, functional description, design and implementation for various parts of computer.
The major hardware components of computer system are:
(a) Input Unit
(d) Output unit
Figure: The basic block diagram of computer system.
The input unit is formed by the input devices attached to the computer. Input devices are used to interact with computer system or used to enter data and instructions to
the computer. Keyboard, Mouse, Scanner etc are some example of input devices.
The basic functions of input unit are:
• It accepts data and instruction from the outside world.
• It converts these data and instruction into computer understandable form.
• Supply the converted data to the computer system for further processing.
Central Processing Unit
CPU is a major component of any computer. It acts as heart and brain of computer, and performs all the processing related activities. It receives data and instructions from outside world, stores them temporarily, processes the data as per the instructions and sends the result to the outside world as information.
The CPU is combination of three components ALU, CU and Registers.
Arithmetic Logic Unit (ALU)
This is the area of CPU where various computing functions are performed. The main functions of ALU are as follows:
• It accepts operands from registers.
• It performs arithmetic and logical operations
• It returns results to register or a memory
The control unit provides the necessary timing and control signals to all the operations in the computer. It controls the flow of data between the CPU and memory and peripherals. The main funtions of control units are given below:
• It performs data processing operation
• It sends control signal to various parts of computer system for controlling
• It gives commands to input data from input unit to memory unit to ALU.
• It transforms result from ALU to memory unit to output unit.
• It gives command to store the data, instruction and program in memory.
Registers are the primary memory of computer system. They are mainly used to store data during the time of processing inside ALU.
The main function
• It holds the address of the active memory locations
• It holds the contents of the accessed (read/write) memory word.
• It holds the address of the next instruction to be executed.
• It holds the data to be operated upon, the intermediate results, and the results of processing.
• It hold the current instruction being executed.
Memory is the part of the computer system that is used to store data or instruction or program temporarily and permanently. Memory is the main storage unit in a computer. In simple terms, memory indicates the primary memory is the main storage unit in a computer. But, memory can be divided into two types primary or main memory and secondary or auxiliary memory.
Alternatively referred to as internal memory, main memory, and primary memory, a primary storage device is a medium that holds memory for short periods of time while a computer is running. Although it has a much
lower access time and faster performance, it is also about two orders of magnitude more costly than secondary storage.
Random Access Memory (RAM) and cache are both examples of a primary storage device.
(This picture is only for students to
Secondary storage is any storage device designed to retain data and instructions (programs) in a relatively permanent form. Secondary storage is non-volatile that is stored data and instructions retain even if the power supply is cut off. It is also called as auxiliary memory or back-up memory.
Some example of secondary memory are Hard disk, Cd, DVD, Floppy disk, Magnetic tape etc.