A typical computer system irrespective of its size, class, or type consists of hardware and software, integrated and harmonized together to perform computational work (scientific or military) or data processing.


Computer hardware consists of the components that can be physically handled. It refers to the physical units or machine of functional units, which makes up the computer configuration which is done to suit the goals and objectives of the user. The function of these components is typically divided into three main categories: input, output, and storage.

Components in these categories connect to microprocessors, specifically, the computerís central processing unit (CPU), the electronic circuitry that provides the computational ability and control of the computer, via wires or circuitry called a bus.

Hardware may be classified into Central Processing Units (CPU) and the peripherals. The CPU entails Control Unit (CU), Arithmetic and Logic Unit (ALU), and the Internal Memory Unit (IMU) or main memory. The peripherals consist of the input, output, and Auxiliary Storage Units.

Strictly speaking, computer is made up of five district elements to include:

  1. A central processing unit (ALU and CU)
  2. Input unit
  3. Output unit
  4. The storage unit (Internal and Auxiliary)
  5. The communication network; ìBusî that links all the elements of the system, and connects the
  6. External world. (Cables and Cords)


The motherboard is a printed circuit board that connects other components through the use of traces or electrical pathways. The motherboard is indispensable to the computer and provides the main computing capability. Personal computers normally have one central processing unit (CPU) on the motherboard.


This is the main brain of the computer that accepts data, performs operations on the data, and sends out the result. Information from an input device or from the computerís memory is communicated via the bus to the
Central Processing Unit (CPU), which is the part of the computer that translates commands and runs programs. It consists of ALU and CU, and a single chip or series of chips that perform arithmetic and logical calculations and controls the operations of the other elements of the system.

Most CPU chips are composed of four functional sections:

  • ALU: Calculating ability either arithmetical or logical operations.
  • Registers: Temporary storage areas that hold data, keep tracks of instruction, and hold the location and
    results of these operations.
  • Control section: Times and regulates the operation of the entire computer system, by using its instruction decoder to read patterns of data in a designated register and translate the patterns into activities, such as
  • addition or comparison. It also uses its interrupt input to indicate the order in which individual operations uses the CPU and regulates the amount of CPU time allotted to each operation.
  • Internal Bus: Network of communication lines that connects the internal elements of the processor and also leads to external connectors that links the processor to the other element of the computer.

The main functions of the microprocessor (CPU clips) includes the following.

a. Control use of the main storage in storing data and instructions (i.e the ROM).

b. Control the sequence of operations.

c. Give commands to all parts of the computer system.

d. Carry out-processing.


The input unit consists of external devicesóthat is components outside the computerís CPU. It provides or fetches information and instructions to the computer. These include keyboard, mouse (mechanical/ optomechanical/ opticals), light pen, joystick, scanner, microphones (voice recognition modules), Optical Character Reader (OCR), Magnetic Ink Character Reader Recognition (MICR), bar code reader, badge reader, digitizer, touch screen, and optical mark reader (OMR).

  • Light pen
  • Mouse
  • Joystick
  • Keyboard
  • Optical Scanner
  • Microphone
  • Modem


Output devices consist of hardware that transfers information from the computerís CPU to the computer user. This includes the monitor, Printer, plotters, or speaker. Video Graphic Adapter: This is a device that converts information generated by the computer into visual information called Monitor. It looks similar to a television set. Information from the CPU is displayed on the screen of the monitor.

Printers: Information and graphics processed or produced with the aid of computer are printed out as hardcopy with the aid of printer. There are different types of printers; Dot-matrix printers, Laser printers, Inkjet, etc.

Plotters: Computer output to microfilm or fiche (COM) which process information on rolls of film (drum plotter) or slide of the film (flatbed plotter).


Storage devices provide permanent storage of information and programs for retrieval by the computer. The two main types of storage devices are disk drives and memory. There are several types of disk drives: hard disk drive, floppy disk, magneto-optical, and compact disk.

Hard disk drives store information in magnetic particles embedded in a disk. Usually a permanent part of the computer, hard disk drives can store large amounts of information and retrieve that information very quickly. The disks are of different sizes such as 1G, 10G, 40G, etc

  • Floppy disk drives
  • Magneto-optical disc drives
  • Compact Disc Drives
  • Digital Video Disc
  • Flash drives
  • Memory Cards


Memory refers to the computer chips that store information for quick retrieval by the CPU. They are basically divided into two ROM and RAM.

Random Access Memory is used to store information and instructions that operate the computerís programs. Typically, programs are transferred from storage on a disk drive to RAM. RAM is also known as volatile memory because the information within the computer chips is lost when power to the computer is turned off or the computer hanged

Read-Only Memory (ROM) contains critical information and software that must be permanently available for computer operation, such as the operating system that directs the computerís actions from start-up
to shut down. ROM is called non-volatile memory because the memory chips do not lose their information when power to the computer is turned off.

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