Computer – Hardware Parts of the Personal Computer

The Major Parts of the Computer :-

• Central Processing Unit (popularly known as CPU)  – it consists of different technical parts like processor, motherboard, hard disc, RAM, CD Drive and cabinet with SMPS.
• Monitor / Screen
• Keyboard
• Mouse

The major accessories of the computer system ?

. In addition to the above referred major components of the computer, we find the following accessories attached to most of the computers :-

• Speakers
• Printers
• Scanners
• Modem
• Microphone

Various Hardware Components of A Personal Computer : 

• PC Case :  It consists of a thin sheet metal enclosure that houses the motherboard, power supply and various drives (HDD, FDD, CD, DVD).  These cases come in two shapes / styles –  desktop and tower.  Now a days the tower type is predominant. It stands upright and is much taller than it is wide. It is usually placed on the floor near the desk or under the top of the desk.  On the other hand desktop version is  pizza box profile and usually placed  on the desktop.
•  Motherboard :   The motherboard is the main circuit board in a PC. It contains all the circuits and components that run the PC.   Major Components found on the motherboard are:

1. CPU -  Full form of CPU is Central Processing Unit or commonly known as processor.    CPU consists of electronic circuits that interpret and execute instructions.  It communicates with the input, output and storage devices.  CPU, with the help of memory, executes instructions in the repetition of machine cycles.   It is the brain of every PC. We can say that the CPU is the hardware device in a computer that executes all of the instructions from the software.  All scheduling, computation and control occurs here.

1. There are two major makers of CPUs namely Intel and AMD.  We often hear that CPU is Intel Pentium or Celeron.  Currently the Pentium chip or processor, made by Intel, is the most common CPU though there are many other companies that produce processors for personal computers. like CPU made by Motorola and AMD.  The speed of a microprocessor is measured in megahertz, or cycles per second.    A MHz is a million machine cycles per second.  A personal computer of 500 MHz has a processor capable of handling 500 million machine cycles per second.  Another measure of speed is gigahertz (GHz), which means a billion machine cycles per second.

• BIOS – Full form of BIOS is  Basic Input Output System.   It is a non-volatile memory that contains configuration information about the PC. It contains all the code required for the CPU to communicate with the keyboard, mouse video display, disk drives and communications devices.

When a PC is powered on it uses the BIOS ‘boot code’ to set up many required functions that bring the PC to a point where it is ready to work.

•   RTC – Full form is ‘Real Time Clock’.   This chip keeps date, day and time in a 24 hour format just like our watch. The PC uses this clock to ‘time stamp’ files as these are created and / or modified.
•      Chip Set - these are large chip(s) that integrate many functions that used to be found in separate smaller chips on the motherboard. They save space and cost.

The functions performed by these chip sets often broken into two devices with one providing an interface from the CPU to the memory and the other providing controllers for IDE, ISA, PCI and USB devices (see below).

In addition to above, in a PC, you will notice a number of connectors on the mother board.

(a)Primary Connectors :  Some of such primary connectors are :

·         (b)Power  - A 20 pin connector accepts a plug from the power supply. This plug carry DC power to all the circuits on the motherboard.

·         ©Keyboard - A Mini-din 6-pin (round) connector found at the back of the motherboard is where the keyboard plugs in.

·         (d) Mouse - A Mini-din 6-pin connector found next to the keyboard connector is where the where the mouse plugs in.

·         (e) Display - This connector is not integrated into the motherboard but is included in this list since its function is absolutely necessary. It is a 15-pin, D-shell type connector found on a video card that plugs into the AGP connector of the motherboard (see below).

 ·         (f) IDE - stands for Integrated Drive Electronics. These are 40 pin connectors that provide a place to connect the ribbon cables from the drives (hard and CD/DVD). All data between the motherboard and the drives is carried in these cables. They are not accessible unless the PC cover is removed.

·         (g) FDD connector - it is similar in function to the IDE connector. It is a 34 pin ribbon connector that carries data between the motherboard and any floppy drive installed in the PC. Not accessible with PC cover on.

·         (h) DRAM - Dynamic Random Access Memory connectors for SIMM and DIMM type memory modules. Not accessible with chassis cover on.

PORTS or Connectors enable us to connect external output or input devices to our computer. The basic types of ports are:  Parallel ports can be used to connect printers, zip drives, video capture (such as Snappy), external hard drives, or digital cameras.   Serial ports that are frequently used to connect all of the above except printers. In addition, there are some serial port mice.  PS2 ports are used to connect some types of mice. There are also places on your computer to attach a keyboard and s-video cable.

(A)Serial Connectors

o    Standard Serial Connector - This connector has been around in PCs since they first appeared. It was originally located on ISA expansion type cards (see below). Today it is an integral part of newer motherboards. It is a 9- pin, D-shell connector that allows you to connect external devices with serial ports to your PC. The maximum data rate is 115 KB/s.

o    USB – Universal Serial Bus This is a relatively new serial bus. Originally specified as low speed, 1.2 Mb/s, it was enhanced to full speed, 12Mb/s. The latest version 2.0 is specified as high speed, 400 MB/s.

Someday USB will completely replace the standard serial connector that has been the workhorse serial port in earlier PCs. USB is now a standard connector on all new motherboards.   Unlike serial and parallel ports, the USB port is designed to power devices connected to it. The devices must be low power devices and must be able to reduce their current draw to less than 0.5uAmps when commanded to do so by the PC.

(B)Parallel Connectors 

o    Centronix or Standard Parallel - This connector has been around in PCs since they first appeared. It has 37-pins and is now integrated on new motherboards. It is usually used to connect your printer to the PC and moves data at about 1MB/s.

o    SCSI - Small Computer System Interface moves data at a maximum of up to 80Mb/s. It not integrated into most PC motherboards. It can be added to a PC as an Expansion card (see below). Some printers and hard disk drives use SCSI interfaces.

Expansion Card Connectors - The CPU connects to expansion card connectors through one of the chip set ICs mentioned above. They are located on the motherboard near the rear of the PC. These connectors allow special function cards to plug into and work with the PC.

Before motherboards integrated the serial and centronix connectors they were found on expansion boards that plugged into ISA slots.

Most PCs have the following expansion connector types:

o    ISA - Industry Standard Architecture connectors have been around since 1980 and first appeared in the IBM XT PC. This type of slot still appears on some newer motherboards so that older expansion boards can still be used. However, many motherboards no longer have ISA connectors on them.

o    PCI - Peripheral Component Interconnect is a newer and faster interface that accepts all expansion cards that have a PCI interface.

o    AGP - Accelerated Graphics Port is a connector that is designed to work with video cards. Your video display plugs into and is controlled by one of these video cards. Many modern video cards offer enhanced 3D-graphics and fast, full motion video.

1. Power Supply :    A power supply is installed in the back corner of the PC case, next to the motherboard.   It converts 120 / 240 vac (standard house power) into DC voltages that are used by other components in the PC.  A 20 conductor cable carries +5vdc, -5vdc +12vdc, -12vdc and ground to the motherboard.

1. MOUSE :   A mouse is an acronym for Manually Oscillating Utensil Sonically Engaged. It is the electronic finger of the computer. One type of mouse has a round ball under the bottom of the mouse that rolls and turns two wheels which control the direction of the pointer on the screen. Another type of mouse uses an optical system to track the movement of the mouse. Laptop computers use touch pads, buttons and other devices to control the pointer. Hand helds use a combination of devices to control the pointer, including touch screens

It is used to point at items in the window environment. The mouse arrow indicates your position on screen. It can change its shape depending upon your position on screen or the program you were using. In a word processor the mouse will appear as a flashing cursor or insertion point. Moving and clicking the mouse can move the cursor onscreen. The mouse has 2 buttons. The left button is used to send signals to programs. The right mouse button gives the user various menus. By double clicking the left mouse button, programs can be opened. A new mouse, the Intellimouse, allows the user to scroll a screen in a program using a center wheel.

5.MONITOR  The monitor is the computer’s screen or display. Monitors come in sizes from 14 inch, 17 inch, to as large as 36 inch monitor. The resolution of the monitor determines the sharpness of the screen. The resolution can be adjusted to control the screen’s display.  The monitor shows information on the screen when you type. This is called outputting information.

When the computer needs more information it will display a message on the screen, usually through a dialog box..

Most desktop computers use a monitor with a cathode tube or liquid crystal display. Most notebooks use a liquid crystal display monitor.  To get the full benefit of today’s software with full colour graphics and animation, computers need a color monitor with a display or graphics cards

6. KEYBOARD :  The keyboard has keys similar to our old typewriter but It also has some additional keys.  The keyboard is used to type information into the computer or input information.

There are many different keyboard layouts and sizes with the most common for Latin based languages being the QWERTY layout (named for the first 6 keys).

Function keys are found at the top of the keyboard. These control programs and are labeled F1 to F12. F1 always provides help in windows environment.

Cursor control keys are arrows that allow you to move the cursor in four directions (up, down, right, left).

Numeric keys are found on the right side of the keyboard and act much like a calculator pad, however, “key must be pressed on in order for these keys to function.

ESC or the escape key allows you to exit or escape some programs.

/ Front slash key is used in web addresses on the Internet.

\ Back slash key signals a sub-directory.

Page up and page down keys allow you to move up or down in a document.

Shift key and caps lock key change the case of the letter when pressed.

ALT key moves the cursor to the menu bar, which is useful in the event the mouse is not functioning.

Pause key pauses text on screen in DOS.

ALT + Ctrl + Delete keys reboots or restarts the computer when they are pushed in that sequence. This is called a warm boot. A cold boot simply means turning the computer off for a minute and then turning it back on. These boots are necessary if a program fails to function.

Backspace key erases errors when the mouse is placed after the error.

Delete key erases errors when the mouse is placed before the error.

7.Printers - The printer takes the information on your screen and transfers it to paper or a hard copy. There are many different types of printers with various levels of quality. The three basic types of printer are; dot matrix, inkjet, and laser.

·         Dot matrix printers work like a typewriter transferring ink from a ribbon to paper with a series or ‘matrix’ of tiny pins.

·         Ink jet printers work like dot matrix printers but fires a stream of ink from a cartridge directly onto the paper.

·         Laser printers use the same technology as a photocopier using heat to transfer toner onto paper.

8.Scanners-   Scanners allow you to transfer pictures and photographs to your computer. A scanner ‘scans’ the image from the top to the bottom, one line at a time and transfers it to the computer as a series of bits or a bitmap.    You can then take that image and use it in a paint program, send it out as a fax or print it.  With optional Optical Character Recognition (OCR) software you can convert printed documents such as newspaper articles to text that can be used in your word processor. Most scanners useTWAIN software that makes the scanner accessible by other software applications.

A Raster Image Processor (RIP) is a component used in a printing system which produces a raster image also known as a bitmap. The bitmap is then sent to a printing device for output. The input may be a page description in a high-level page description language such as PostScript, Portable Document Format, XPS or another bitmap of higher or lower resolution than the output device. In the latter case, the RIP applies either smoothing or interpolation algorithms to the input bitmap to generate the output bitmap.

9.Digital cameras allow you to take digital photographs. The images are stored on a memory chip or disk that can be transferred to your computer. Some cameras can also capture sound and video.