K.B.H.POLYTECHNIC,MALEGAON CAMP, MALEGAON.

COMPUTER HARDWARE & MAINTENANCE.

S.Y.C.M/I.F

Guided By :- Mr.K.S.Pawar.

Lecturer in Computer Department

Chapter No :- 1Introduction

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Computer Mother board and its constituent components

A typical PC mother board with important components is given below:

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The main circuit board which connects all the device on a microcomputer Also called main board or

system board. 1. Mouse & keyboard

2. USB3. Parallel port4. CPU Chip5. RAM slots6. Floppy controller7. IDE controller8. PCI slot9. ISA slot10. CMOS Battery11. AGP slot12. CPU slot13. Power supply plug in

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1. MOUSE & KEYBOARD

  Keyboard Connectors are two types basically.

the smaller mini DIN PS/2-style keyboard connector.                   

You can use an AT-style keyboard with a PS/2-style socket (or the other way around) by using a converter. Although the AT connector is unique in PCs, the PS/2-style mini-DIN is also used in more modern PCs for the mouse. Some keyboards have a USB connection, but these are fairly rare compared to the PS/2 connection keyboards.  

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2. USB (Universal serial bus) : 

USB is the General-purpose connection for PC. You can find USB versions of many different devices, such as mice, keyboards, scanners, cameras, and even printers. a USB connector's distinctive rectangular shape makes it easily recognizable.           USB has a number of features that makes it particularly popular on PCs. First, USB devices are hot swappable. You can insert or remove them without restarting your system.

3. Parallel port: Most printers use a special connector called a parallel

port. Parallel port carry data on more than one wire, as opposed to the serial port, which uses only one wire. Parallel ports use a 25-pin female DB connector. Parallel ports are directly supported by the motherboard through a direct connection or through a dangle.

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4. CPU Chip : The central processing unit, also called

the microprocessor performs all the calculations that take place inside a pc. CPUs come in Variety of shapes and sizes.    Modern CPUs generate a lot of heat and thus require a cooling fan or heat sink. The cooling device (such as a cooling fan) is removable, although some CPU manufactures sell the CPU with a fan permanently attached.

5. RAM slots : Random-Access Memory (RAM) stores

programs and data currently being used by the CPU.RAM is measured in units called bytes.RAM has been packaged in many different ways. The most current package is called a 168-pin DIMM (Dual Inline Memory module).   

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6. Floppy controller: The floppy drive connects to the computer via a 34-pin ribbon cable, which in turn connects to the motherboard. A floppy controller is one that is used to control the floppy drive.

7. IDE controller: Industry standards define two common types of hard drives: EIDE and SCSI.  Majority of the PCs use EIDE drives. SCSI drives show up in high end PCs such as network servers or graphical workstations. The EIDE drive connects to the hard drive via a 2-inch-wide, 40-pin ribbon cable, which in turn connects to the motherboard. IDE controller is responsible for controlling the hard drive.

8. PCI slot:  Intel introduced the Peripheral component interconnect bus protocol.  The PCI bus is used to connect I/O devices (such as NIC or RAID controllers) to the main logic of the computer. PCI bus has replaced the ISA bus.

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9. ISA slot:  (Industry Standard Architecture) It is the standard architecture of the Expansion bus. Motherboard may contain some slots to connect ISA compatible cards.

10. CMOS Battery: To provide CMOS with the

power when the computer is turned off all motherboards comes with a battery. These batteries mount on the motherboard in one of three ways: the obsolete external battery, the most common onboard battery, and built-in battery.  

11. AGP slot:  If you have a modern motherboard, you will almost certainly notice a single connector that looks like a PCI slot, but is slightly shorter and usually brown. You also probably have a video card inserted into this slot. This is an Advanced Graphics Port (AGP) slot  

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12. CPU slot: To install the CPU, just slide it straight down into the slot. Special notches in the slot make it impossible to install them incorrectly. So remember if it does not go easily, it is probably not correct. Be sure to plug in the CPU fan's power.  

13. Power supply plug in: The Power supply, as its name implies, provides the necessary electrical power to make the pc operate. the power supply takes standard 110-V AC power and converts into  12-Volt, 5-Volt, and 3.3-Volt DC power.

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PROCESSOR MODES There are three different modes of operation, that resulted

from the evolution of the PC from its humble beginnings with the Intel 8088 chip.

Real Mode :- DOS is by its nature a single-tasking operating system,

meaning it can only handle one program running at a time. the processor in a mode that would be compatible with the original Intel 8088 chip. This is called real mode. Real mode is of course used by DOS and "standard" DOS applications. In fact, today there are relatively few simple DOS programs that just use the standard 640K that DOS makes available.

Protected Mode :- the 80286 chip in the IBM AT, a new processor mode

was introduced called protected mode. This is a much more powerful mode of operation than real mode, and is used in all modern multitasking operating systems. Support for virtual memory, which allows the system to use the hard disk to emulate additional system memory when needed.

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Virtual Real Mode :-

The third mode of processor operation is actually an additional capability, an enhancement, of protected mode. Protected mode is normally used to run graphical multitasking operating systems such as the various flavors of Windows.

A protected mode operating system such as Windows can in fact create multiple virtual real mode machines, each of which appear to the software running them as if they are the only software running on the machine.

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MEMORY ORGANIZATION Conventional Memory :-

Size of the conventional memory is 640 KB and it is used by the Disk Operating System (DOS) and other programs such as WordStar, Lotus etc. This memory is also called DOS Memory or BASE Memory. DOS cannot use more than 640 KB for most of its work.

Extended Memory :-

The memory area lies above 1 MB limit is called Extended Memory. Extended Memory is available in 286 and later processor based computers. 286 processors can support extended memory up to 16 MB and 386 processors can support upto 4 GB. The extended memory is not much useful for the DOS users as DOS doesn’t know how to use this memory area. But, for Windows and OS/2 user this memory is very useful as these operating systems can use extended memory. The user can view the memory details by typing "mem" command in the command prompt.

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Virtual Memory Virtual memory is a part of the hard disk which is

used as a memory. It has a set of memory addresses and stores the instructions or the data. When the processor executes the instructions, it converts the virtual memory addresses into real memory addresses. The main use of the virtual memory is to increase the address space.

Static random access memory (SRAM) is a type of semiconductor memory where the word static indicates that, unlike dynamic RAM (DRAM), it does not need to be periodically refreshed, as SRAM uses bistable latching circuitry to store each bit.

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CACHE MEMORY Cache Memory is a high speed memory buffer

that temporarily store data, the processor needs.

the processor can retrieve data from catch faster than from main memory.

Depending on where the cache is residing there are two types of cache memory's as :-

i. Internal cache(L1)ii. External cache(L2)

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Internal Cache(Level 1 cache(L1)) :- The L1 cache is built into the processor die,

hence it is called as internal cache. This cache memory area of very fast

memory built into the processor chip. Its runs at the full-core speed of processor.

External Cache(Level 2 cache(L2)) :- The L2 cache is mounted on the

Motherboard that is external to the processor,so it is called as External cache.

Its runs motherboard speed,for faster data access a larger cache level 2 can be used.

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Level 3 Cache (L3 Cache) :- The additional L3 cache is built on the motherboard

in between CPU and main memory.

CPU

L2 Cache

Main memory

L1 Cache

Secondary Memory

L3 Cache

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What is RAM? Random Access Memory.

RAM is volatile.

1– Static RAM.

2– Dynamic RAM.

• Static RAM

Fast, has lower access time.

Typical access times 5-25 ns.

Expensive.

Cache memory is Static RAM.

• Dynamic RAM

Slower, has higher access time than Static RAM.

Typical access times 60-120 ns.

Much cheaper than SRAM.

Main Memory is Dynamic RAMMr.K.S.Pawar

DDR :- SDRAM (Double Data Rate SDRAM)- Allows activationof the output operation to occur on both rising and falling clockedge and hence doubles the speed of operation.

• RDRAM (Rambus DRAM) - Developed by Rambus and Intel, can support very high bus speeds.

• Memory Slots/Sockets on Motherboard

1.SIMM (Single In-Line Memory Module)2.DIMM (Dual In-Line Memory Module)

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Chipset

The chipset controls the system and its capabilities. It is the hub.

Chipsets are integrated, and are not upgradable without buying a whole new motherboard.

Some of the items it dictates Memory controller Real-time clock Keyboard and mouse controller Secondary cache controller PCI bridge EIDE controller

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Form Factors :- The form factor is the physical size and

Dimensions of the motherboard. The form factor determines the general layout, size,

and feature placement on a motherboard.

BIOS What is it? - Basic Input Output System Why is it necessary? – boot up System • Important Functions Check CMOS Set-up. POST - Power On Self Test.

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Configuring BIOS Display system setting. Initiate bootstrap sequence. System Time/Date. Boot Sequence. Plug and Play. Drive Configuration. Security. Power Management.

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FIGURES

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