COMPUTE R HARDWARE Powered by DeSiaMore1. CONTENTS MOTHERBOARD ROM-CHIP CMOS BIOS POST SYSTEM BUS...

COMPUTER HARDWARE

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CONTENTS

MOTHERBOARD ROM-CHIP

CMOS

BIOS

POST

SYSTEM BUS

INTERRUPTSPowered by DeSiaMore 2

Introduction to the PC A computer is a device or set of devices which work

under the control stored program (which can be changed ), automatically accepting and processing data to produce information

Mainframes are the very largest computers - million dollar

machines, which can occupy more than one room, An example is IBM model 390.

Minicomputers

are large powerful machines. They typically serve a network of simple terminals. IBM's AS/400 is an example of a minicomputer.


Workstations

are powerful user machines. They have the power to handle complex engineering applications. They use the UNIX or sometimes the NT operating system. Workstations can be equipped with powerful RISC processors like Digital Alpha or MIPS.

PC's are the Benjamin's in this order: Small

inexpensive, mass produced computers. They work on DOS, Windows, or similar operating systems. They are used for standard applications.


The PC consists of a central unit (referred to as the computer) and various peripherals. The computer is a box, which contains most of the working electronics. It is connected with cables to the peripherals.


MAINFRAME COMPUTER


MINICOMPUTER


PC`s


System ResourcesPCs have four types of system resources:—Interrupt Request (IRQ) lines,Storage,I/O ports,and memory ranges. Many system components and peripherals require one or more of these resources, which raises the twin problems of resource availability and resource conflicts. Resource availability is particularly important with regard to IRQs, which are in high demand, and of which only 16 exist. Resource conflicts can occur when two devices are assigned the same resource, in which case one or both devices may not function, or may function unpredictably. Resource conflicts may occur even with plentiful resources, such as I/O ports, where many are available and only a few are in use.


PERIPHALS DEVICE

Peripherals devices can be external such Mouse, Keyboard, Monitor, External-Zip drive or scanner or internal such as a CD-ROM drive or internal Modern.


Processor Speed

Amount of Memory

Hard-disk free Space

System bus speed

Graphic acceleration Cards(Video Cards)

SYSTEM PERFORMANCE


MOTHERBOARD(MAIN BOARD)

The motherboard is also called the system board or the main board. Everything else in the system plugs into, is controlled by, or depends on the motherboard to communicate with other devices on the system. The system board is the largest of the printed circuit boards. Every system has one.


ATX MortherBoard


The system board generally houses the following components

The CPU The controller circuitry The bus The RAM The expansion slots for additional boards The ports for external devices The Complementary Metal-Oxide Semiconductor

(CMOS, pronounced C moss) The other Read Only memory (ROM) The BIOS chips The support chips providing varied functionality Jumpers Powered by DeSiaMore 15

There are TWO type of Motherboard

1. AT

2. ATX (Advanced Technology EXtended motherboard) The PC

motherboard that superseded the Baby AT design. The ATX layout rotated the CPU and memory 90 degrees, allowing full-length expansions to be plugged into all sockets. The power supply blows air over the CPU rather than pulling air through the chassis.


When you turn power on, several things happen in the PC:

You hear the fan motor starting. There are one or more cooling fans in the PC. They produce a whirring sound. After a few seconds, text starts to scroll on the screen. Now the PC tests and counts the RAM. You see a number on the screen. It increases in size.

THE Pc START-UP PROCESS


To understand the working of the PC, it is useful to study the PC start-up process. Those are events, which take place from power-on until the PC is ready to work. Remember, the PC can do nothing without receiving instructions. These instructions are commands, which are sent to the CPU. During start-up, the PC reads the commands in this sequence:

Cont…….

First it receives commands from the ROM chips. Those chips are inherent in any computer. They contain the POST andBIOS instructions, which we will look at shortly. Next, the operating system is read from the hard disk (or from floppy drive A). This is called the boot process.


ROM (Read Only Memory). The ROM chips are on

the system board. They contain. system software.

System software are

instructions, which enable the PC to coordinate the

functions of various computer components.

The ROM chips contain instructions, which are

specific for that particular system board. Those

instructions will remain in the

PC throughout its life. They will usually not be

altered. Primarily, they are start-up instructions.

The ROM chips


start-up instructions. For most users, they are all woven together. You can differentiate between:POST (Power On Self Test) The Set-up instructions, which connect with the CMOS instructions BIOS instructions, which connect with the various hardware peripherals The Boot instructions, which calls the operating system (DOS, OS/2, or Windows,Linux) All these instructions are in ROM chips, and they are activated on by one during start-up.


POSTPower On Self Test is the first instruction executed during start-up. It checks the PC components and that everything works.You can recognize it during the RAM test, which occurs as soon as you turn power on.


If POST detects errors in the system, it will write error messages on the screen. If the monitor is not ready, or if the error is in the video card, it will also sound a pattern of beeps (for example 3 short and one long) to identify the error to the user.

*POST also reads those user instructions, which are found in CMOS:


For example, POST cannot by itself find sufficient information about the floppy drive(s).

Floppy drives are so "dumb," that POST cannot read whether they are floppy drives or not, nor what type. About the same goes for IDE hard disks, while EIDE hard disks are a little more "intelligent," However, POST still needs assistance to identify them 100% correctly. The same goes for RAM:

POST can count how much RAM is in the PC. However, POST cannot detect whether it is FPM,EDO or SD RAM. Since the CPU and BIOS reads data from RAM chips differently, depending on the RAM type, that type must be identified.


CMOS


CMOS (Complimentary Metal Oxide Semiconductor) is a small amount of memory in a special RAM chip. Its memory is maintained with electric power from a small battery. Certain system data are stored in this chip. They must be read to make the PC operable. There may be 100 to 200 bytes of data regarding DATE, TIME, FLOPPY and HARD DISK DRIVER, and much more.CMOS data can be divided in two groups:

Data, which POST can find during the system test.

Data, which contain user options.

CMOS battery Cont…………


The start the BIOS programs are from a ROM chip. BIOS abbreviation of (Basic Input/Output System) and those are programs, which are linked to specific hardware systems. Is typically placed in a Rom chip that come with computer.

It contains the program code required to control all the basic operating components of the computer system. In other words, the BIOS contains the software required to test hardware at boot up, load the operating system, and support the transfer of data between hardware components.

BIOS


The BIOS programs control hardware, the user (programmer) controls hardware via a call to BIOS.

BIOS typically occupy 1MB, and the programs are saved ROM chip on the system board.During start-up, BIOS is read from ROM chips.That information is supplemented with the system data saved in CMOS.


PORTSPC PORTsThe Pc user a number of different connector or ports to attach input, output and input/output.

SERIAL PORT

Transmits data one bit at a time and can do so in both direction .A single wire is used for transmitted data and another wire for received data normally used nine-pin connector.

TYPE OF PORTS

SERIAL PORT

PARALLEL PORT


PARALLEL PORT

Transmits many bits at once. In modern PCs the single parallel port carries 8-bits signals so that a whole byte can be sent at once.

UNIVERSAL SERIAL BUS (USB)

This is a relatively new form of connector. It utilies a rectangular plug providing a high speed serial connection.

Expandability:USB allow u to daisy chain up to 127 devices

Support PnP

Allow hot swapping

Cable length:15 feet 15m.Powered by DeSiaMore 33

SYSTEM BUSSystem-bus connects together Processor, Main-Memory and I/O-Controllers.Data could travel (usually 32-bits side-by-side i.e. in bit-wise parallel), a pathway along which the address specifying a particular desired memory location could travel, and a few other lines which would tell the memory whether to store (write) or retrieve


The busses are the PC`s express way. They are “wires ” on the circuit board, which transmit data between different components. One “wire” can move one bit at a time The data flow on the system board,u will find the CPU, which is the “brain” of the PC and the busses.

The busses are the nerve system of system system-board. They connect the CPU to all other components.There are least at three busses.

Data-BusControl-BusAddress-Bus


Control Bus

Is bidirectional bus, meaning that signal can be carried in both directions.

Typical control lines include:Memory write: To send data to memoryMemory Read: To send data to from memory.I/O write: To send data to be output to specific I/O port.I/O read: To send data from a specific I/O portBus request- When a component is requesting control

of the system bus.Interrupt request: To indicate that an interrupt is

pendingInterrupt acknowledge: to confirm that an interrupt

has been acknowledgedClock: To synchronies operationsReset: Initializes all the components.

Transfer acknowledges confirming that transferred either on or off the data bus.


DATA BUSTypical data bus consists of 8, 16 or 32 separate lines. Moving data and instructions between system components.ADDRESS BUSWhen process wishes to read a word of data from memory, it first puts the address of the required word on the address bus


Is a signal from one device /source seeking the attention of the processor. Signal to indicate that attention from the processor is required.

INTERRUPT

If interrupt an enabled, on receipt of an interrupt the currently executing program is suspended in an orderly fashion and control is passed to an interrupt service routine


There are least are four type of an interrupts;

PROGRAM

Generated by a times within the processor to allow the operating system to perform certain function at regular interval of time.

TIMES

Generated by some condition that occurs as a result of an instruction execution or attempt to execute an illegal machine instruction.


I/OGenerated by I/O controller to signal normal completion of an operation or to signal a variety of error condition

HARDWARE FAILUREGenerated by a failure such as power failure on memory parity error.


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