Do you know your computer components?
Below are the basis computer hardware that run inside your computer(new/old).
Center Unit ProcessorsCPU is the brain of any computer.
It controls all activities inside the computer. Basically it performs 2
types of operations - arithmetic & logical operation (internally),
operations are performed on 2 types of devices - I/O and memory
devices. It uses the “address bus” to select any “location” on these
devices, sends a read/write signal over the “control bus” and then the
information over the “data bus”.
Memory DevicesThe CPU stores all information in the computer’s memory. There are two memory types - RAM & ROM
RAM (Random Access Memory):This volatile type is a read & write memory device. This loses its contents when power is shut off.
The types of RAM are:
- DRAM (Dynamic ram) – is similar to a capacitor, as it tends to lose its contents and hence requires to be refreshed. This is the Computer RAM.
- SRAM (Static ram)
– Is faster than Dram and doesn’t require to be refreshed. This is
costly and hence only a limited amount is used as CACHE memory in the
computer.
- DDR= (Double Data Rate SDRAM)DDR has doubles
the rate of data transfer of standard SDRAM by transferring data on the
up and down tick of a clock cycle.It is incompatible with SDRAM
physically, but uses a similar parallel bus, making it easier to
implement than RDRAM, which is a different technology.
ROM (Read only memory):ROM
can be programmed using a programmer and then it acts as a “read only”
device. This device is used as the textbook for the CPU in the computer
and is called ROM BIOS. It stores all the basic information of
programming the devices present inside the system as well as the POST
(Power On Self Test) sequence. AMIBIOS and AWARD BIOS are the most
common ROM BIOS.
The types of ROM are:
- PROM (Programmable Read Only Memory)
- EPROM (Erasable & Programmable Read Only Memory)
- FLASH ROM
- EEPROM (Electrically EPROM)
- EAPROM (Electrically Alterable ROM)
-DVD-ROM
I/O DEVICES:Apart
from passive memory devices, there are certain controllers in the
system, which assist the CPU in performing various operations. These
are referred to as I/O devices. These devices include Interrupt
controller, Timer, Ports, DMA Controller, Floppy Drive Controller, CRT
Controller etc.
BUSES & EXPANSION SLOTS:These
are the means through which communication between various devices of
the computer takes place and the types are as mentioned below.
MCA BUS (Micro Channel Architecture):
MCA
bus is available either in 16 bit or 32 bit versions. It was developed
in a new line of computers called the PS/2 (personal system 2). The
clock speed is slightly faster (10MHZ instead of 8MHZ).
EISA BUS:
EISA has a 32-bit Address and Data bus and 10MHZ CLK speed.
VL BUS/VESA LOCAL BUS:It
is a 32-bit bus which was positioned local to the CPU and hence its
name. Therefore it could support high bus speeds (that of the CPU).
PCI BUS:PCI
has many benefits over other bus types. First of all, it supports 64
bit and 32-bit data paths. So it can be used both for 486 and Pentium
based systems. PCI can run up to 33MHZ speed and has the advantage of
being isolated from the CPU. INTEL developed this bus.
PCMCIA: (PC Memory Card International Association):*
The
PCMCIA was first designed for expanding the memory in small, handled
computers. PCMICIA’S bus width is only 16 bits, but a 32-bit version is
on its way. There are three types of cards namely
- Type 1 (3.3 m thick)- used for memory card.
- Type 2 (5 mm thick)- used for modem and LAN adapter.
- Type 3 (10.5 mm0 thick) - used for most common applications like PC hard disk Cards.
ADD ON CARDS:These
are cards plugged on to the main board, the mother board (The one that
houses the CPU & RAM/ROM Bios). Each performs specific functions of
interfacing the Motherboard to peripheral device like mouse, Monitor
etc. Some Add-ons are discussed below.
DISPLAY ADAPTER:These
interface the mainboard with the monitor and there are several types of
cards. The variations are in resolution, no. Of colors supported and
speed.
PCI Express (Peripheral Component Interconnect Express), It's new generation of graphics cards,officially abbreviated as
PCIeMost computer use the PCI-express graphic card now.
EGA (Enhanced Graphics Adapter):*
640 X 350 mode
VGA (Video Graphics Adapter):*
Advanced versions of SVGA/TVGA which start from a resolution of 640 X 480 pixel
AGP (Accelerated Graphics Port):*
Introduced in the celeron/P II based systems, this caters to the demanding multimedia applications with its high performance.
IDE I/O CARD:Supports the following functions.
SERIAL PORT:Communication
external to the computer is done serially (bit after bit) through this
port. It is used to connect communication devices like mouse, modem etc.
PARALLEL PORT:
8 Bit data transfer takes place between the computer and an external device. It is typically used to connect a printer.
GAME PORT:It is used to connect a joystick for playing games.
IDE (Integrated/Intelligent Drive Electronics) Interface: This interface is used to communicate with IDE Hard disks.
USB interface.
SOUND CARD:This
is the card that adds audio effects to the computer .Most of the
computer has build in the card. The advance user might get external
card for building up Multimedia Computers.
PERIPHERAL DEVICES:FLOPPY DRIVES:*
replace By thumb drive/flash drive. Thumb drive is re-writable and holds memory without a power supply.The storage space up to 2Gb.
HARD DISK DRIVES:ST
506 & ESDI are old types. IDE hard disks are popular because their
price to performance ratio is very good. For very high performance,
SCSI (Small Computer Systems Interface) is the ideal option, if price
is not a criterion.The Last er trend is SATA 1 and SATA 2.SATA hard
disc has double the speed of ATA interface hard disc..
ROM DRIVES:CD/DVD
ROM drive is used in a multimedia system as it can support all types of
CD ROMs/DVD-Rom – be it data CD, Audio CD, Video CD. It has a great
advantage of storing about 650 MB of data in a single CD.and DVD
storage up to 4 Gb.
KEYBOARD:Keyboard translates
the keystrokes into letters or numbers. These letters are interpreted
and the computer CPU depending executes commands on what was sent.
Variations in terms of XT/AT, no. of keys, type of keys used may be
observed.
MOUSE:To interact with the pictures
(ICONS), a special pointer device was introduced into the computer
world. This device is known as mouse and is connected to the serial
port/USB.
The mouse contains a round ball that makes contact
with two rollers-one for X-axis (the horizontal) and one for Y-axis
(the vertical).
With the optical sensor and bluetooth technogy,the mouse can be use without wire-wireless mouse.
SCANNERS:In
addition to keyboards and pointing devices, there is another very
common method of getting data into the computer. A Scanner is used to
scan an image (say from a photo) and editing may be done using a
suitable software.
MONITORS:The monitor receives
video signals from the computer video adapter card and displays the
video information as pixels (picture elements) on the monitor screen. A
variety of monitors ranging from CGA mono to SVGA colour are available
for users to choose from (though the former is totally obsolete).
The LCD Monitor(liquid crystal display monitor)
LCDs
use 2 sheets of polarizing material with a solution of liquid crystal
between them. An electric current passes through the liquid causes the
crystals to align so that light can not pass through them. Each
crystal, therefore, is like a shutter, either allowing light to pass
through or blocking the light.
Comparison between LCD monitor and CRT monitor.
Configuration Setup:This
is where we define the system configuration. This is done only when the
system is assembled and configured for the first time or when it is
upgraded. (One may enter the SETUP by pressing “Del” key as the system
is powered up).
Different BIOS’ support different options but the most essential ones, which are found on all systems, are listed below.
DATE & TIME: It displays the correct Date & Time. It has to be set when system is first installed.
FLOPPY TYPE:*Replace By USB thumb drive.
To define the Floppy drives connected (1.2MB or 1.44MB).
HARD DISK TYPE: To select the Hard disk type (Primary or secondary and slave or master)
DISPLAY TYPE: Its select the types of video adapter used for the system monitor.
CACHE ENABLE/DISABLE:
This category speeds up the Memory access. (Default value: Enable) and defines presence or absence of cache memory.
QUICK POWER ON SELF TEST: Its speeds up the Power On Self Test after you power up the computer.
PASSWORD SETTING: This allows you to set the System password.
POWER MANAGEMENT: This category allows you to select the type (or degree) of power saving.
LOADING DEFAULT VALUES:There
are many parameters, which need to be defined in the CMOS setup, and
one may not want to do so manually. This option loads certain default
values, stored in the BIOS ROM, which have been defined by the
manufacturer for optimal system performance.
ENABLE/DISABLE ON BOARD FUNCTIONS:To
enable/disable certain onboard functions like Floppy Disk Control etc
(This applies only to integrated Motherboards where the ADD ON
functions are integrated on the Motherboard itself).
PNP FEATURES: This category is used to configure the PCI Bus slots.
IDE AUTO DETECTION*: This allows you to detect the IDE Hard drives automatically.
*Replace By SATA.
SAVING & EXITING:This allows you to save the new setting value in the CMOS memory and continue with the booting process.
POST (POWER ON SELF TEST):This
POST firmware is stored in ROM on the motherboard. This POST is a
series of a simple program to test and catch faults in different
components and circuits. It tests the microprocessor, interrupt
controller, PPI, DMA controller, ROM, RAM, peripheral controllers etc.
SYMPTOMS:In case of error detection during POST, indications like error beeps/error messages helps troubleshoot problems.
DISPLAYED ERROR MESSAGES:When system is powered on, error message will be displayed on the screen (Floppy disk fail), if the Video Adapter is functional.
DIAGNOSTIC CARDS:The
advanced diagnostic add on card captures details of POST sequence and
displays a hexa code which may be used for in-depth & accurate
diagnosis of a POST problem.
CDROM DRIVES:A
computer CD-ROM drive uses small, interchangeable, plastic-encased
discs from which data is retrieved using a laser beam, much like music
compact disc. And like a music CD, a computer CD-ROM stores vast
amounts of information. This is achieved by using light to record data
in a form that’s more tightly packed than the relatively clumsy
magnetic read/write heads a conventional drive must manage.
The
drive is controlled by a software in your PC that sends instructions to
controller circuitry that’s either a part of the computers motherboard
or on a separate board installed in an expansion slot.
How a CD_ROM drive works?
-
A motor constantly varies the rate at which CD-ROM disc spins so that
regardless of where a component, called DETECTOR, is located in
relation to the radius of the disc, the portion of the disc immediately
above the detector is always at the same speed.
- The laser projects a concentrated beam of light that is further focused by a focusing coil.
-
The laser beam penetrates a protective layer of plastic and strikes a
reflective layer that looks like aluminum foil on the bottom of disc.
-
The surface of the reflective layer alternates between lands and pits.
Lands are flat surface areas; pits are tiny depression in the
reflective layer. these surface are record of the 1s and 0s used to
store data.
- Lights that strikes a pit scattered. But light
that strikes a land is reflected directly back at the detector, where
it passes through a prism that deflects laser beam to a LIGHT-SENSING
DIODE.
- Each pulse of light that strikes the light-sensing
diode generates a small electrical voltages. These voltages are matched
against a timing circuit to generates a stream of 1s and 0s that can
understand.
