Computer Hardware

The word computer comes from the word compute which means to calculator so computer is normally considered to a calculating device, which perform arithmetic operations at enormous speed .It is a programmable machine. This means it can execute a programmed list of instructions and respond to new instructions  that is given.

computer generations
· ENIAC-Electronic Numerical Integrate and calculator.
· EDVAC- Electronic Discrete variables automatic computer.
· UNIVAC- Universal Automatic Computer.
· BINAC- Binary Automatic Computer.
Functional block of computer
· Input
· Memory
· Arithmetic And Logic
· output
· Control unit

Classifications of computer
· Micro computer
· Mini computer
· Mainframe

· Super computer

Mother Board
Mother board is the largest circuit board inside the computer .It contains the computer’s C.P.U (central processing unit), memory (RAM and ROM) and various support chips for C.P.U.
Motherboards divisions
· Bus Based computers
· Single Board Based Computer



Motherboard components
· Processor Area
· Memory Area (RAM and ROM)
· Expansion Slot Area
· Peripheral Area

PROCESSOR SOCKET ARCHITECTURE
· SMT   –    Surface mounting Technology.
· DIP    --    Dual In-line pin.
· PLLC   --   Plastic Leadless chip cartridge.
· LIFA    --   Low insertion force Architecture.
· ZIFA    --    Zero Insertion Force Architecture.

Co-processor
                      Co-processor is a special purpose microprocessor used to speed up main processor by taking over some of  the main processor work.
Most common type of co-processor are-
· Math co-processor
· Graphic co- processor





FLASH MEMORY
                                   A new type of EEPROM (Electrically Erasable programmable Read Only memory) that can be erased and reprogrammed using the normal operating voltage found inside the pc is called flash memory.



PHYSICAL ORGANISATION OF MEMORY
· SIPP   –  Single  In line Pin Package.
· DIPP  --  Dual In line Pin Package.
· SIMM – Single In line Memory Module.
· RIMM – Rambus In line Memory Module.
EXPANSION SLOT AREA
· ISA --  Industrial Standard Architecture.
· EISA – Extended Industrial  Standard Architecture.
· MCA – Micro Channel Architecture.
· VESA --Video Electronics Standard Association.
· PCI --   Peripheral component Interconnect.
· AGP—Accelerated Graphics Port .
· USB—Universal Serial Bus.
· AMR—Audio Modem Riser.
· CNR—Communication Network Riser.
· IEEE –Institute of Electrical and Electronic Engineers.
PERIPHERAL ARE
Peripheral refers to any external device connected to computer
Key board Interface
·   DIN – Deutsche Industrial Norm
-     5 pin connector
·   Ps/2 – personal system
-   6 pin  connectors
-   It is a mini DIN
·    USB
·      Mouse interface
-   Ps/2
-   Serial -9 pin ,Dsaped,female,2row
-   USB

·  I/O ports
1.  parallel port
-   No. of pins – 25
-   No. of rows- 2 row
-     Type-  Female
2.  Serial port
-   COM 1 – 25  PIN
-   COM2 -  9 PIN
· FDD Connector(FLOPPY DISK DRIVE)
- IDE Standard
- 34 pin
· HDD connector (HARD DISK DRIVE)
- IDE controller
- IDE 1 (master slave)
- IDE 2 (master slave)
  IDE controller supports 2 device. Total 4 device support.
· Display adaptor
-   15 pins
-   3 row
-   D shaped
-   Female connector
· Game/Midi port
-  15 pin
-  2 row
-  D shape
-  Female connector
· NIC-(Network Interfacing card)
- RJ 45 connector is used
· USB
· IEEE


Bus Mastering
                                               Bus mastering allow the peripheral devices to take the control of the bus form the cpu for a short time. Using this facility the devices can transmit or receive large blocks of data  in  a short burst modes.
Motherboard form factor
 The form factor of mother board determines the specifications for its shape and size. It is the physical size and dimensions of the mother board.
- AT-advanced technology
- BABY AT
- ATX
- MICRO ATX
CD (Compact Disk)
  A    CD mode of
- 1.2  millimeter  thick
- Poly carbonate plastic used
- Weight 15-200gram
DVD (DIGITAL VERSATILE DISC DIGITAL VIDEO DISC)
12 cm type is standard DVD
BLUE RAY DISC
The capacity of this type of disk is 25GB  to 50GB for single layer and double layer disks respectively. These are once writable disks. It is suitable for back up/archival memory. Its data transfer rate is 72mbps.
BOOTING
                          This process of loading the operating system (OS) from devices into the computer’s memory is called booting of  the computer’s memory is called “Booting Of the computer”
Booting 3 TYPEs
- Local Booting – Floppy  ,CD.
- Normal Booting-Hard disk.
- Remote Booting-network.
3 files are needed for booting
- I/O
- MS DOS
- COMMAND.COM
ROM SHADOWING
The shadowing procedure copies the ROM into RAM and then assigns that ram the same address as the ROM originally used, disabling the actual ROM in the process. This makes the system seem as through it has ROM running at the same speed as RAM.


Duties of OS
- I/o management
- Memory management
- File management
- User management
PARTITION
- primary dos partition
- extended dos partition

    Partitioning is basically done for having more than one operating system on the same drive and more than one logical drive when a disk is partitioned the partition program FDISK write a MBR(Master Best Record) .
   The FDISK program enables us to create two FAT partitions.
- a primary DOS partitions.
- an extended DOS partitions.
FORMATTING
  TO use a floppy disk and only one formatting is required, where as a hard disk drive required a low level and high level formatting to make it useful for data storage.
-A high level formatting is done on the hard disk to make the disk dos compatible by writing DBR, FATs and the empty root director entry information on the drive.
-A low level formatting does the job of magnetically dividing the disk into tracks and sectors.
VIRUS
Computer virus is a self – replacing  piece of  computer code that can partially or fully attach to computer files or applications.
General Virus Type
-Boot Sector Virus
-File virus
-Macro virus
-Multiple virus
-Polymorphic virus
-Stealth virus

BIOS
BIOS is term that stands for basic input output system.
 Basic functions of BIOS
-INITIALIZATION.
-POST [POWER ON SELF TEST]
-BSL [BOOT STRAP LOADER]
INITIALIZATION
It initialise all the peripherals which is connected to the system.
POST
The POST test your computer processor , memory , chipset , video adapter, disk controller, disk drives, keyboard and other circular components. It is set of program loaded from the BIOS ROM during the system power on time. This system ensure that all major system components are present and are working  properly. After POST process if everything is functioning properly then BIOS loads the operating.
POST- Error checking devices in mother boar          
ERROR
-Fatal error
-Non fatal error
· Post sequences
-Processor Test
-Bios Rom Test
-Timer 1 test
-DMA channel 0 Test
-Base 16K DRAM Test
-CRT Controller Test
-Mother board support Chip Test
-RAM Test
-Optional Rom test
-Peripheral controller Test
BSL (BOST STRAP LOADRE)
 After the POST,BIOS contains a program called bootstrap loader.

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