Functional Units of Computer

 Every functional system incorporates some functional parts that constitute a consumable product. Similarly, there are some functional units of the computer that constitute in producing logical outputs.

The five basic functional units of a computer are:

• Input unit,
• Aprocessing unit (Arithmetic and logic)
• Amemory to store final or intermediate results
• A controlling unit that coordinates functions of every unit, and
• An output unit

In this post, we will discuss all the functional units of the computer.

Functional Unit of Computer

The functional units of a computer, i.e. input unit, arithmetic and logic unit, memory, control unit, and output unit, all are connected to the interconnection network that helps them in exchanging information, as you can see in the image below. Now, let us explore each functional unit separately.

Input Unit :    The input to the computer is either data or instruction that guides the arithmetic and logic unit about what operations have to be performed and also controls the movement of data between the computer and its I/O devices.

Now, the input, i.e. data or instruction, is accepted with the help of input units such as a keyboard, mouse, touchpad, joystick, and trackball. The most familiar device that we use to accept input is the ‘keyboard’ and ‘mouse’. All of these input devices are graphic input devices, and you can see their effect on the display unit.

Whenever you strike any key on the keyboard, it gets converted to binary code and is handed over to the processor, which interprets the code and performs the appropriate action.

For audio and video input, microphones and cameras are used, respectively. Now a day, the internet can also be used to issue input to a computer from other computers or databases.

Memory Unit

A memory unit is required to store the programs that have the set of instructions that instructs the Arithmetic and logic unit in which operation has to be performed. It also stores the data associated with the program. Memory can further be classified into three types:

Primary memory is also known as the main memory or the random-access memory (RAM). It is the fastest accessible memory of the computer. If a program has to be executed, it first needs to be placed in the primary memory. Then the instructions of the program are fetched one at a time by the processor for execution.

The memory is organized in such a way that in one basic operation, one word can be retrieved from the memory, or one word can be stored in the memory. A word length could be 16, 32, or 64 bits.

The primary memory is expensive as well as faster. But primary memory is volatile in nature it does not retain its content when the power gets off.

Secondary Memory

Secondary memory is the hard disk of your system; it also includes flash drives, optical disks, and magnetic disks. It is slower and less expensive as compared to primary memory. It doesn’t lose its contents even if the supply of power gets off.

We require secondary memory to store a large volume of data or program permanently or the data that is less likely to be retrieved.

Cache Memory

Cache memory can be accessed much faster than primary memory, and it is even smaller in size. It is stored with the data that is required frequently by the processor.

As we know, the program to be executed and the data associated with it are brought to the primary memory, and the processor fetches the program instructions from there. The process also places a copy of the instructions and associated data in the cache memory.

Now, the instructions that are required to be executed repeatedly, such as loops, are retrieved from the cache memory to improve the execution rate.

Arithmetic Logic Unit

The arithmetic logic unit of the processors performs all the arithmetic operations. Arithmetic operations include addition, subtraction, division, multiplication, comparison between numbers, etc.

The ALU unit performs the operations present in the instruction and stores the result in the memory. It also stores the intermediate results of the operation in the registers.

The arithmetic operation is performed on the operands. The operands are placed into the registers, which store one word at a time which is sufficient for an operand. Retrieval of the data from registers is even faster than the cache memory.

Output Unit

A computer is a functional unit, and as it has an input unit to accept the input, it also has an output unit to provide the generated output by the system. The most familiar device used to output a result is a printer.

A display screen is also an output unit as it displays the generated result, but it also displays the input provided to the system. That’s why the display screen is termed the ‘I/O unit’ because of its dual function.

Control Unit

The functions of input, ALU, memory, and output unit require coordination so that everything goes in sequence, i.e. the processor accepts input, places it in memory, processes the stored input, and generates output. The control unit coordinates the entire sequence.

In this way, the functional units of computers cooperate to generate useful output.