Draw the block diagram of a computer system. Briefly write about the functionality of each component.

The block diagram of the computer system is shown below:

1. Input Unit — An input unit takes/accepts input and converts it into binary form so that it can be understood by the computer. The computer input constitutes data and instructions.

2. Central Processing Unit — CPU is the control centre or brain of a computer. It guides, directs, controls and governs all the processing that takes place inside the computer. There are mainly three components of a CPU:

   1. Arithmetic and Logical Unit (ALU) — The ALU performs the arithmetic (+, -, *, /) and logical (AND, OR, NOT, XOR) operations sent from the memory, performs specific operations (addition, subtraction etc) and the result is returned to the memory.

   2. Control Unit (CU) — The CU controls the flow of data from input devices to memory and from memory to output devices.

   3. Registers — These are high-speed temporary storage areas found in CPU. Registers work as per the instructions given by the control unit (CU), storing instructions and data immediately required for performing an operation.

3. Memory Unit — Memory unit is used as a storage unit for program as well as data. The memory can be both primary and secondary depending upon its location in the computer system. The primary memory, also termed as main memory, is directly accessible to the CPU since all the work is done in the RAM and later on gets stored on the secondary storage. On the contrary, the secondary memory, also known as auxiliary memory, can be accessed by the CPU through input-output controllers or units.

4. Output Unit — Output unit is formed by the output devices attached to the computer. Output devices produce the output generated by the CPU in human readable form.