Structure/Components of a Digital Computer 

  • Each computer consists of a series of devices that together operate as an integrated unit or computer system.
  • The processor is made up of the memory, arithmetic, logic and control units.
  • A large computer system will normally have one or more auxiliary units, where input and output data are stored.
  • The major key elements of a digital computer are – Central Processing Unit(CPU)/ Operational Unit, Input Unit, Output Unit and Memory/Storage Unit. These all are located directly or indirectly on mother board.
  • Computer System : 
    • The collection of all the necessary components of a computer system to execute it successfully constitute a system unit.
    • It normally includes cpu, peripherals and others. 
  • CPU Cabinet/System Unit/Computer Case :
    • A box- like structure that contains almost all the components of a computer inside it.
    • A computer case covers the computer circuitry.
    • It is also known as cabinet, box, computer chassis etc.
    • It is a box which contains different components of a computer like CPU, Motherboard, RAM, Power supply unit etc. It contains motherboard as major structure but also includes several ports & connectors, SMPS etc.
    • Computer cases are available in many different forms and sizes like desktop cases, full-size tower cases, mini tower cases etc.
    • ATX is the most popular form factor used for desktop computer these days.
    • Computer case includes input/output ports and power buttons.
    • Motherboard is a main component placed inside the computer case.
    • The power supply unit is also attached with the case. A power supply unit is responsible for providing power to other components of a computer.
  • Mother Board/Main Board/System Board : 
    • It is a printed circuit board on which a number of devices are plugged in.
    • This printed circuit board is often called the mother board.
    • The motherboard contains the circuitry and connections that allow the various components to communicate with each other.
    • Motherboard holds some of the most important component of the computer system.
    • In a typical computer microprocessor, main memory and other components are connected to the motherboard.
    • It acts a s a base for other components.
    • Motherboard also provides connectors for several other devices.
    • A motherboard allows many different parts of our computer to receive power and communicate with one another.
    • The shape , size and layout of a motherboard is called a form factor.
    • The Motherboards usually provides the interface between the CPU memory and input/output peripheral circuits, main memory, and facilities for initial setup of the computer immediately after power-on.
    • All other major components of the computer are either plugged in directly to this mother board or connected through a bunch of wires.
    • CPU, RAM and Device Cards are plugged in various slots of the mother board. Devices like Hard Disk, Floppy Drive, CDROM Drive, which are attached to the CPU cabinet, are connected through wire ribbons.
    • The mother board has printed circuitry which allows all these components to communicate with each other.
    • The motherboard is the main circuit board of a microcomputer.
    • It is also known as the main board or system board.
    • It is the circuit board in which all the components are connected through cable within a personal computer.
    • Many devices are connected with motherboard directly or indirectly.
    • Motherboards usually provide the interface between the CPU memory and input/output peripheral circuits, main memory, and facilities for initial setup of the computer immediately after power-on.
    • Some major parts of a motherboard are : –
      (a) ATX Power Connector :
      • ATX stands for Advanced Technology Extended (ATX) power connector is used to connect computer’s power supply to motherboard.

  (b) AGP Slot :

      • Accelerated Graphics Ports (AGP) is a point-to point channel which is used  to attach a video card to a motherboard.

(c) CD-in Header : –

      • At this, CD drive is plugged in or connected or attached .

(d) FDD Header :

      • Floppy Disk Drive (FDD) header is used for Floppy drive. Now this slot is obsolete because floppy disks are outdated.

(e) HDD Headers : –

      • Hard Disk Drive header is used for connecting to hard disk .

(f) PCI Slots : –

      • It is used for connecting the PCI (Peripheral component interconnect) card.

(g) USB Headers : –

      • It is a group of pins to which an internal USB cable can be attached to provide extra USB ports.
      • These ports are used for attaching external/auxiliary devices such as pen drive, printer etc.
  • SMPS (Switch Mode Power Supply) :
    • A power supply or power supply unit (PSU) is an internal component used to supply the power to the components of a computer.
    • Power supply is rated by the number of watts it generates.
    • CPU cabinet also houses a power supply unit which provides power to all the components of the computer system.
  • Ports and Connectors.
    • On the back end of the CPU cabinet, we have seen that a number of connection slots, technically called Ports and Connectors.
    • These slots are used to connect various input/output devices such as keyboard, mouse, printer, scanner, to the computer.
    • They act as interface between the peripheral devices and CPU directly or indirectly to communicate each other.
  • Operational Unit : 
    • It is the functional unit of a computer.
    • To complete operations successfully, the computer allocates the task among its various functional/operational units. These are 1) arithmetic logical unit, 2) control unit, and 3) central processing unit.
  • A typical computer consists of – 

(A) CPU (B) Input Unit (C) Output Unit (D) Main Memory 

    (A) CPU :

     (For More Details, Click this Link)    

    (B) Input Unit (IU) :

                       (For More Details, Click this Link)                               

    (C) Output Unit (OU) :

    (For More Details, Click this Link)     

    (D) Main Memory :

                            (For More Details, Click this Link)     

    Von Neumann Architecture :

    • Mathematician John Von Neumann conceived a computer architecture which forms the core of nearly every computer system in use today. This architecture is known as Von Neumann architecture.
    • It is a design model for the modern computers which has central processing unit (CPU) and the concept of memory used for storing both data and instructions.
    • This model implements the stored program concept in which the data and the instructions both are stored in the memory. All computers share the same basic architecture which have memory, an I/O system, arithmetic logic unit (ALU) and control unit (CU).

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