MODULE 5

Main Components of Motherboard

CPU Socket & Memory Slots

ISA, PCI & AGP Expansion Slots

CMOS Battery

Power Connectors

Memory Slots

Chipset

Serial/ Parallel/ USB etc ports.

Industry Standard Architecture (ISA)

ISA Contd… First open system bus architecture. IBM introduced this 8-bit bus architecture in 1981. It had transfer

rate of 4 MB/sec. in 1984, with the release of the 286 data processor which used a

16-bit data path, the ISA bus was expanded to 16 bits, with data rate 8MB/Sec.

A major disadvantage of this bus was that IRQs had be manually defined through jumpers .

Peripheral Component Interconnect (PCI Slots)

PCI Contd..

Introduced by Intel in 1992. Widely in use today.

Requires an additional bridge chip to connect to the I/O of the CPU.

Operates on 33MHz, & capable of transferring data at 132 MB/sec.

PCI Contd..

Important feature of PCI is the model for the PNP (Plug-n-Play) specification, which means that PCI cards could be configured via software, rather than through jumpers as was the case with ISA cards.

Accelerated Graphics Port (AGP)

AGP Contd.. The AGP port is a dedicated graphics port based on PCI.

It’s a dedicated point-to-point channel that enables the graphics controller to access main memory, bypassing the bottleneck of the PCI bus.

It allows textures to be stored in main memory rather than video memory.

AGP Contd..

• The AGP channel is 32 bits wide and • Runs at 66 MHz, giving a bandwidth of

266 MB/sec. • AGP also supports two optional faster

modes, giving throughputs of 533 MB/sec and 1.07 GB/sec.

Random Access Memory (RAM)

Old 72-pin SIMM-type memory sockets

168-pin DIMM-type memory sockets

RAM CHIPS

Single In-line Memory Module (SIMM) A SIMM is a small circuit board designed to hold a

set of RAM chips.

Two types of SIMM's have been in general use. 30-pin SIMM's and 72-pin SIMM's.

30-bit SIMM's have 8-bit data buses; 72-pin SIMM's have 32-bit data buses.

Dual Inline Memory Module (DIMM)

DIMMs have separate electrical contacts on each side of the module.

DIMMs have a 64-bit data path.

Enhanced Integrated Drive Electronics (EIDE slot)

EIDE Contd.. Enhanced (sometimes "Expanded") IDE is a standard electronic

interface between your computer and its mass storage drives.

Makes it possible to address a hard disk larger than 528 Mbytes.

EIDE also provides faster access to the hard drive, support for Direct Memory Access (DMA), and additional drives, including CD-ROM

Analog Audio Input Connectors

Analog Audio Input Connectors

These are typically used for CD ROM drives. Since the CD ROM drive can deliver audio via the 40-pin IDE connection, the analog audio connectors are not generally needed. If you have a video capture card, you may need to use the analog audio input to get the sound into the computer.

front panel switches and LEDs

front panel switches and LEDs

There are typically 4 connections (hard drive LED, power/message LED, power switch and reset switch).

The LED connections are polarity sensitive (if connected in reverse, the LEDs will not work).

The colored wire is generally positive and the white/black wire is negative.

I/O Ports

Mouse & Keyboard Connectors

AT motherboard Power Supply

ATX Power

ATX Power

Chipset A chipset or chip set refers to a group of integrated circuits, or

chips, that are designed to work together. The chipset is the heart of the computer and is the hub for all data

transfer. It determines how fast components like the processor, memory, keyboard and various plug-ins can function in relation to each other

Chipset

Northbridge

The actual function of a chipset is to communicate between all components of the modern PC.

The Northbridge usually contains the CPU interface and the memory controller, sometimes the graphics unit is also on the Northbridge.

Southbridge

The southbridge mainly deals with Input Output devces.

The Southbridge contains at least a PCI controller, floppy/ IDE/ hard disk controllers, serial and parallel ports, USB support and power management functions.

BIOS

BIOS A BIOS (Basic Input/Output System) is an electronic set of

instructions that a computer uses to successfully start operating.

A main function of the BIOS is to give instructions for the power-on self test (POST).

It gives the computer basic information about how to interact with some critical components, such as drives and memory

ZIF Socket

ZIF Contd..

ZIF is an acronym for zero insertion force, a concept used in the design of IC sockets, invented to avoid problems caused by applying force upon insertion and extraction.

ZIF Contd..

ZIF Contd..

CPU Fan Connector

CPU Fan Connector

Hard Disk Storage

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Objectives

In this chapter, you will:

Understand how hard drives read and write data Know the difference between tracks, sectors,

and cylinders Understand the difference between high-level

and low-level formatting Identify the major internal components and

understand the workings of a typical hard drive Identify cables and connectors used with hard

drives

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Definition

A hard disk drive is a sealed unit that a PC uses for nonvolatile data storage.

A hard disk drive contains rigid, disk-shaped platters, usually constructed of aluminum or glass

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Drive Operation

The basic physical construction of a hard disk drive consists of spinning disks with heads that move over the disks and store data in tracks and sectors.

The heads read and write data in concentric rings called tracks, which are divided up into segments called sectors, which normally store 512 bytes each.

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Drive Operation

One side of a platter is called a “head”.

Hard drives can have different numbers of platters, depending on their design and storage capacity.

On the heads, you will see concentric rings (tracks) and pieces of rings (sectors) just like on the floppy disks.

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Drive Operation

Many hard drives today use a technology called “zone bit recording”

Which enables the hard drive to have more sectors on the outer tracks, where there is more room than on the inner tracks.

This allows more room for storage

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Original

Zone Bit

Drive Operation

Another logical unit of a hard drive is the cylinder.

Let’s say we have a disk drive with three platters. Imagine passing a cylinder down through both sides of each platter (6 tracks).

These 6 tracks make up a logical cylinder on the disk.

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Computer Data Storage

The read/write head on the drive moves very close to the spinning disk as it goes by and writes to specific concentric rings on the disk, called tracks.

The electrical particles on the disk are arranged according to the charge given to them by the head.

The head can read the magnetic data as it passes by, or write to it by using an electrical charge.

Preparing a disk drive for data

storage involves three steps:

Low-Level formatting (LLF) Partitioning High-level formatting (HLF)

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Low Level Formatting

Low level formatting marks the tracks and sectors of the disk.

A sector is a small section of a track that stores 512 Bytes of information

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Track

Sector

Partitioning Partitioning a disk is the act of

defining areas of the disk for an operating system to use.

Partitioning is required because a hard disk is designed to be used with more than one operating system.

Partitioning enables a single hard disk drive to run more than one type of operating system (dual boot), or it can enable a single operating system to use the disk as several volumes or logical drives.

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Partitioning

You decide you want to break the 10GB space into three logical partitions: one with 5GB of space, one with 3GB, and one with 2GB.

The operating systems will logically view these three partitions as three separate drives and gives them separate drive letters C:, D:, and E:.

Physically all you have is one hard drive with three logical drives.

Hard drive partitions must always begin at C:; because the A: and B: drives are reserved for floppies.

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High Level Formatting

A part of the system area is called the “Master boot sector”. This is the process of creating the disk's logical

structures such as the file allocation table and root directory.

The Master boot sector is: Always the first sector (sector 0) of the first track (track

0) of the first cylinder (cylinder 0) disk.

512 bytes long, just like any other sector

Contains information on all logical drives, regardless of whether they are bootable.

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High Level Formatting

Formatting also creates the root directory. (C:\)

If the disk is to be made bootable, COMMAND.COM and two system files (io.sys and msdos.sys) must be in the root directory of the bootable drive.

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Components

The basic components of a typical hard disk drive are as follows: Disk platters

Read/write heads

Head actuator mechanism-Spindle motor (inside platter hub)

Logic board (controller or Printed Circuit Board)

Cables and connectors

Configuration items (such as jumpers or switches)

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The platters, spindle motor, heads, and head actuator mechanisms usually are contained in a sealed chamber called the Head Disk Assembly (HDA).

Platters

A hard disk drive has one or more platters, or disks.

Most hard disk drives have two or more platters, the number of platters a drive can have is limited by the drive's vertical physical size.

Platters have traditionally been made from an aluminum/magnesium alloy, which provides both strength and light weight. However, manufacturers' desire for higher and higher densities and smaller drives has led to the use of platters made of glass.

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Recording Media

No matter which substrate is used, the platters are covered with a thin layer of a magnetically retentive substance, called the medium, on which magnetic information is stored. Two popular types of magnetic media are used on hard disk platters:

-Oxide medium

-Thin-film medium

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Drive Operation: magnetization

HDDs record data by magnetizing ferromagnetic material directionally, to represent either a 0 or a 1 binary digit.

The Co-based alloy thin films are polycrystalline and the size of grains has an order of 10 nm.

In practice, a group of grains (about 100) are magnetized as one bit.

The read-and-write head is used to detect and modify the magnetization of the material immediately under it. There is one head for each magnetic platter surface on the spindle, mounted on a common arm.

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Read Write Heads

A hard disk drive usually has one read/write head for each platter surface These heads are connected, or ganged, on a single movement mechanism.

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Air Filters

Nearly all hard disk drives have two air filters.

One filter is called the recirculating filter, and the other is called either a barometric or breather filter.

These filters are permanently sealed inside the drive and are designed never to be changed for the life of the drive.

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HD heads are kept from contacting the platter surface by the air that is extremely close to the platter; that air moves at, or close to, the platter speed.

Spindle Motors

The motor that spins the platters is called the spindle motor because it is connected to the spindle around which the platters revolve. Spindle motors in hard disk drives are always connected directly; no belts or gears are involved.

The spindle motor also must be precisely controlled for speed. The platters in hard disk drives revolve at speeds ranging from 3,600 rpm to 15,000 rpm or more.

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Logic Boards

All hard disk drives have one or more logic boards mounted on them.

The logic boards contain the electronics that control the drive's spindle and head actuator systems and present data to the controller in some agreed-upon form.

On ATA drives, the boards include the controller itself, whereas SCSI drives include the controller and the SCSI bus adapter circuit.

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Cables and Connectors

Hard disk drives typically have several connectors for interfacing to the computer, receiving power, and sometimes grounding to the system chassis. Most drives have at least these three types of connectors:

-Interface connector(s)

-Power connector

-Optional ground connector (tab)

The interface connectors are the most

important because they carry the data

and command signals between the

system and the drive.

The power connector is usually the same four-pin type that is used in floppy disk drives, and the same power-supply connector plugs into it. 04/19/23 68

Configurations Items

To configure a hard disk drive for installation in a system, you usually must set several jumpers (and, possibly, terminating resistors) properly.

Master, Slave, and Cable Select are different configurations you can select with jumpers

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IDE Hard Drive Originally hard drives required a separate plug-in

controller to connect the drive to the rest of the system.

IDE: Integrated Device Electronics. Today’s hard drives have the controller built onto the drive rather

than using a separate controller. This shortens the distance between the controller and the hard drive and eliminates the interference problem inherent with older drives.

It is the most widely-used hard drive interface on the market. The fancy name refers to how the IDE technology "integrates" the

electronics controller into the drive itself.

The IDE interface, which could only support drives up to 540 MB has been replaced by the superior EIDE (Enhanced-IDE) technology which supports over 50 GB and allows for over twice as fast data transfer rates.

The other most common hard drive interface is SCSI, which is faster than EIDE, but usually costs more. 04/19/23 70

ATAPI Devices ATA: AT Attachment.

The specification, formulated in the 1980s by a consortium of hardware and software manufacturers, that defines the IDE drive interface.

AT refers to the IBM PC/AT personal computer and its bus architecture. IDE drives are sometimes referred to as ATA drives or AT bus drives.

Shortly after the introduction of the IDE drive, CD ROM drives were being added to the system to add multi-media capabilities. With the new ATAPI (Advanced Technology Attachment

Packet Interface) standard devices like CD ROM drives, Tape Drives, Zip Drives, and DVD Drives could share the same IDE hard drive cable.

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SATA Drives Serial ATA was designed to replace the older ATA (AT

Attachment) standard (also known as EIDE). It is able to use the same low level commands, but

serial ATA host-adapters and devices communicate via a high-speed serial cable over two pairs of conductors.

Serial ATA has distinct key advantages over its predecessor. Cables are very thin with small 7-pin connectors. They can be up to 3 feet (1 meter) in length, and are easily routed to stay out of the way allowing maximum airflow inside the case.

ATA cables limited to 18 inches (46 cm) in length often made connections difficult and also clogged cases blocking airflow, while cooling has become crucial.

SATA also has a far lower power requirement of just 250 mV compared to PATA's 5-volt requirement, and with chip core voltages declining, this speaks well of SATA's future.

First generation SATA has a maximum transfer rate of 150 MBps, and second generation SATA delivers 300 MBps. A third generation SATA set for 2009, "SATA 6Gb/s" will deliver roughly twice the speed of the previous SATA iteration. 04/19/23 72

SATA Drives

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Floppy A floppy disk is a data storage

medium that is composed of a disk of thin, flexible ("floppy") magnetic storage medium encased in a square or rectangular plastic shell.

Invented by IBM, floppy disks in 8-inch (200 mm), 5¼-inch (133.35 mm), and 3½-inch (90 mm) formats enjoyed many years as a popular and ubiquitous form of data storage and exchange, from the mid-1970s to the late 1990s.

They have now been largely superseded by USB flash drives

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8-inch, 5¼-inch, and 3½-inch floppy disks

Floppy

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Disk format Year introduced

FormattedStorage capacityin KB (1024 bytes) if not stated

Marketedcapacity¹

8-inch - IBM 23FD (read-only) 1971 79.7 ?8-inch - SSSDIBM 33FD / Shugart 901

1973 237.25 3.1 Mbits unformatted

8-inch - DSSDIBM 43FD / Shugart 850

1976 500.5 6.2 Mbits unformatted

8-inch DSDDIBM 53FD / Shugart 850

1977980

- 1200 (MS-DOS FAT)1.2 MB

5¼-inch DD 1978 360 or 800 360 KB3½-inchHP single sided

1982 280 264 kB

3-inch 1982 360 125 kB

3½-inch (DD at release) 1984720 (400 SS, 800 DS on

Macintosh, 880 DS on Amiga)1 MB

5¼-inch HD 1982 YE Data YD380 1,182,720 bytes 1.2 MB3-inch DD 1984 720 ?2-inch 1985 720 ?5¼-inch Perpendicular 1986 100 MB ?

3½-inch HD 1987 14401.44 MB (2.0 MB

unformatted)3½-inch ED 1987 2880 2.88 MB3½-inch Floptical (LS) 1991 21000 21 MB3½-inch LS-120 1996 120.375 MB 120 MB3½-inch LS-240 1997 240.75 MB 240 MB3½-inch HiFD 1998/99 150/200 MB 150/200 MB

Floppy The A: and B: drives on a

desktop computer are reserved in the BIOS for floppy disk drives. As most computers only come with

one floppy disk drive only the A: drive will be visible in file explorer.

If a second floppy disk drive is fitted then both A: and B: drives will be visible.

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Ribbon cable used to connect floppy.To indicate which end of the cable is pin 1 on a drive cable, a stripe is drawn on the edge of the cable.