The core elements of a computer include ALU (Arithmetic & Logic Unit), Memory or Storage Unit, Control Unit and I/O devices (Input & Output Devices). The memory unit, control unit and ALU is clubbed as a CPU (Central Processing Unit).
CPU (Central Processing Unit)
The CPU is considered the brain of the computer. It controls all parts of the computer including data processing (like storing data, retrieving data, executing data).
Control Unit
It performs all tasks except the data processing acts. It obtains the instructions from the memory, intercepts it and directs the following operation. It also communicates with the input and output devices. It is regulates the transfer of data.
ALUÂ
The Arithmetic and Logic Unit is a circuit that performs arithmetic and logical functions.
The arithmetic function involves mathematical functions like subtraction, addition, division, multiplication, etc.,
The logical function involves functions like selecting, matching, sorting, etc.,
I/O Unit
The Input and output devices are the interface for the user and the computer to access the data from the user and provide the processed data to the user. The input devices like keyboard, mouse, joystick, barcode scanner, etc., is used to input the data into the computer. The computer processes the data and provides the data back to user through output devices like monitor, printer, graphic plotter, etc.,
Memory Unit
The computer’s memory unit consists of RAM (Random Access Memory) and ROM (read Only Memory). The RAM first gets instructions which then passes to the processor which processes and sends back. The Random access memory is also called as Read/Write memory, which is the temporary memory of a computer. The ROM is a special memory which is read only memory, writing and erasing is not possible by user without specialised equipment.Read only memory can be manufacturer-programmed or user-programmed only.
Memory unit is the amount of data that can be stored in the storage unit. The data storage is in binary digits 0 & 1 (Passive and active state component of circuitry).
1 Bit  means 0 or 1
Group of 4 bits means 1 Nibble
Group of 8 Bits means 1 Byte
1024 Byte = 1 Kilobyte (KB)
1024 Kilobyte = 1 Megabyte (MB)
1024 Megabyte = 1 Gigabyte (GB)
1024 Gigabyte = 1 Terabyte (TB)
1024 Terabyte = 1 Petabyte (PB)
1024 Petabyte = 1 Exabyte (EB)
1024 Exabyte = 1 Zettabyte (ZB)
1024 Zettabyte = 1 Yottabyte (YB)
