presentation on various interfacing standards:-ata /eide, scsi

PresentationOn

Various Interfacing Standards:-ATA /EIDE, SCSI

Presented To Ms. Veena Menon Mr. Abhishek Tripathi

Presented By Reena Jain Rimi Malaiya

Computer Technology & Application Department

2012-2013

CONTENTS Introduction History ATA(Advanced Technology Attachment) ATA version

Types of ATA Performance of ATA Features Disadvantages of ATA

EIDE(Enhanced Integrated Drive Electonics) Function Features of EIDE

EIDE V/S IDE

History SCSI Interface(Small Computer System Interface) SCSI Configuration

SCSI Variation SCSI Hardware SCSI Adapter SCSI Connector SCSI Phases and commands SCSI Terminator Advantage and disadvantage of SCSI

Summary Bibliography

INTERFACE Interface is a boundary across which two independent systems meet and act on or communicate with each other.

The various interfacing standard includes the different way of interfacing through the use of different standard.

Various interfaces are ATA , EIDE , SCSI and Fire Wire.

FEATURES OF INTERFACE

Performance

Connectability

Cost

DESIGN DIFFERENCES OF INTERFACE

The interface appear at two level:-

Device level Interface

System level Interface

Design Difference

DEVICE LEVEL INTERFACE

A Device level interface is designed to link particular kind of device to its host.

The interface is particular to the signals developed by that device and will generally work with no other.

For Example: telephone jack , electric outlet.

SYSTEM LEVEL INTERFACE A system level interface connects at a higher level, after all the signals from the device have been converted to the kind used by the host computer system.

The signals used by the a system level interface are not specific to any single kind of device.

For example tape drive , hard disks , floppy disk and even scanners and printers can use the same system level interface.

ATA ATA stands for ‘Advance technology attachment’. The term IDE, or "Integrated Drive Electronics," is also used to refer to ATA drives

The dominant hard disk interface for the computer has become the AT Attachment design.

Computers can use ATA hard drives without a specific controller to support the drive. The motherboard must still support an ATA connection, but a separate card (such as a SCSI card for a SCSI hard drive) is not needed.

Diagram of ATA

It was developed and championed by Compaq in 1984.

Compaq contacted Western Digital (Hard Disk controller manufacturer) to build a controller that could be mounted directly on the hard disk.

In a short period, many other computer and disk drive manufacturers found IDE/ATA to be advantageous and began implementing own proprietary flavours.

ATA was first approved in 12 may 1994 under the ANSI document number X3.221-1994

HISTORY

Standard Year Introduced Maximum capacity Maximum speed

ATA 1994 504MB(CHS only) 4.17 Mbps

ATA-2 1996 137.5GB 11.3Mbps

ATA-3 1997 137.5GB 16.7Mbps

ATA-4 1998 137.5GB 33.3Mbps

ATA-5 2000 137.5GB 66.6Mbps

ATA-6 2002 16PB 133Mbps

ATA-7 Proposed 16PB 133Mbps

ATA STANDARDS

ATA was first developed by Control Data Corporation, western Digital and Compaq.

First utilized an 8-bit or 16-bit interface with a transfer rate of up to 8.3 MB/s.

It support for PIO modes 0, 1, and 2. Today, ATA and ATA-1, are considered obsolete.

ATA-1

http://www.computerhope.com

ATA-2, more commonly known as EIDE and sometimes known as Fast ATA or Fast IDE.

It is a standard approved by ANSI in 1996 under document number X3.279-1996.

ATA-2 introduces new PIO modes of 3 and 4, transfer rates of up to 16.6MBps and DMA modes 1 and 2.

It supports drives up to 8.4GB. Today, ATA-2 is also considered obsolete.

ATA-2

ATA-3 is a standard approved by ANSI in 1997 under document number X3.298-1997.

ATA-3 added additional security features and the new S.M.A.R.T feature.

ATA-3


ATA-4 is a standard approved by ANSI in 1998 under document NCITS 317-1998.

ATA-4 includes the ATAPI packet command feature, introduces UDMA/33, also known as ultra-DMA/33.

It is capable of supporting data transfer rates of up to 33 MBps.

ATA-4



ATA-5 adds support for Ultra-DMA/66, which is capable supporting data transfer rates of up to 66 MB/s. It has the capability of detecting between 40 or 80-wire cables.

ATA-5



ATA-6 added support for Ultra-DMA/100.

It has a transfer rate of up to 100MBps.

ATA-6


TYPES OF ATA

There are two kinds of ATA: PATA

SATA

Parallel ATA (PATA) is an IDE standard for connecting storage devices like hard drives and optical drives to the motherboard.

PATA generally refers to the types of cables and connections that follow this standard.

ATA was renamed to Parallel ATA when the newer Serial ATA (SATA) standard came into being.

Parallel ATA cables transfer data 16 bits at a time.

The traditional cable uses 40-pin connectors attached to a ribbon cable.

Each cable has two or three connectors, one of which plugs into an adapter interfacing with the rest of the computer system. The remaining connector(s) plug into drives

PATA

PATA cable will be black, gray and blue while the connectors on a 40-wire cable will only be black.


http://en.wikipedia.org/wiki/File:Nappe.svg

Low costs

Large capacity

ADVANTAGES

Older ATA adapters will limit transfer rates according to the slower attached device.

Only ONE device on the ATA cable is able to read/write at one time.

Limited standard for cable length (up to 18inches/46cm).

DISADVANTAGE

SATA(Serial ATA) Looking to the future, on the 15th of February, 2000, Intel, along with several drive-makers including APT, Dell, IBM, Maxtor, and Seagate Technology, announced a radically new conception of ATA that they called Serial ATA.

Seagate demonstrated the first Serial ATA drive in June 2002.

Serial ATA uses a point-to-point connections scheme. That is, only one device connects to each Serial ATA port.


The initial specification for Serial ATA calls for an initial peak transfer rate of 150MBps, a little more than a 10-percent improvement over the current top speed for conventional parallel ATA, 133MBps.

The Serial ATA system is the smaller cable that it used to connect the drive to the computer. Instead of a wide 40- or 80-conductor ribbon cable, Serial ATA will likely use a four-conductor cable with compact connectors, similar to those of USB and FireWire.


SERIAL ATA CABLE


Low costs

Large capacity

Faster transfer rates compared to ATA.

Smaller cables for better heat dissipation.

ADVANTAGES

PERFORMANCE OF ATA

As engineers refined the ATA standard, they increased performance by adding new transfer modes to the operating features of the drive.

The current ATA standard recognizes 11 transfer modes, each with its own performance limit.

AT Attachment supports two broad classes of transfers: Programmed Input/Output (PIO) and Direct Memory Access (DMA).

DMA is further divided into Single-Word DMA, Multi-Word DMA, and Ultra DMA modes.

CONNECTOR FOR ATA

An AT Attachment interface uses any of three connectors for its interface . The most common has 40 pins to accommodate its addressing, data, and control signals.

The 40-pin ATA connector

A 50-pin connector additionally allows four vendor-unique pin assignments, which are typically used for indicating master or slave status for a given drive.

The 50-pin ATA connector (of which the 44-pin connector is a subset).

It Stands for "Enhanced Integrated Drive Electronics.“

EIDE is an improved version of the IDE drive interface that provides faster data transfer rates than the original standard.

While the original IDE drive controllers supported transfer rates of 8.3 Mbps. EIDE can transfer data up to 16.6 Mbps, which is twice as fast.

EIDE

The term EIDE can be a bit ambiguous, since it technically refers to an ATA standard known as ATA-2 or Fast ATA.

Therefore, the terms EIDE, ATA-2, and Fast ATA may be used synonymously.

EIDE may also refer to the ATA-3 standard, which is similar to ATA-2, but includes additional features.

ATA-3 supports the same maximum data transfer rate as ATA-2, but has SMART support and uses a 44 pin connector.

While EIDE was the most common drive controller used for many years, it has since been replaced by updated versions of the ATA standard that support Ultra DMA.

These include the ATA-4 through ATA-7 standards, which provide data throughput rates from 33 to 133 Mbps.

Most modern computers use a completely new standard called "Serial ATA," or SATA which supports even faster transfer rates.

FUNCTIONS EIDE is a PATA technology, meaning data is transmitted in parallel (or side by side) across 16 of the wires in the cable.

EIDE drives use a ribbon cable that contains 40 connectors, but 80 wires. Each of the 40 connectors connects to a wire with one wire.

Data transfer is actually the movement of electricity.

FEATURES OF EIDE EIDE drives, under the ATA-2 standard, supported transfer rates up to 16.6 MBps (Mega Bytes per second).

This means it could transfer roughly four mp3 songs in one second.

It also supported DMA (Direct Memory Access) modes 1 and 2. DMA allows the hard drive to place data directly into system memory, by passing many controllers and improving overall performance.

It was also the first standard to support Large Block Addressing (LBA). LBA is what first allowed drives to be larger than 528 MB.

EIDE VS. IDE CABLE EIDE cables have 80 wires while IDE cables have 40 wire.

EIDE channels allow to carry more information at the same time and transmit more signals to appropriate system-designated areas than IDE.

EIDE standard developed for faster transfer speeds and it is more- advanced drive setups.

HISTORY The original SCSI standard evolved from another called SASI , the shugart associates standard interface.

In 1981 by hard disk pioneer shugart associates working with NCR corporation.

SCSI-1 is the original SCSI standard developed back in 1986 as ANSI X3.131-1986. SCSI-1 is capable of transferring up to eight bits per second.

SCSI-2 was approved in 1990, added new features such as Fast and Wide SCSI, and support for additional devices.

SCSI-3 was approved in 1996 as ANSI X3.270-1996.

SCSI stands for Small Computer System Interface,SCSI,pronounced as "Scuzzy“.

It allows a variety of devices such as hard drive, optical disk drive, tape drive, printer, and scanner to interface to the computer.

The devices linked to the SCSI bus are called SCSI devices.

SCSI has data transfer rates up to 80 MB/s.

Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices.

SCSI is a device independent bus.

SCSI INTERFACE

The SCSI standards define commands, protocols, and electrical and optical interfaces.

SCSI is capable of supporting eight devices, or sixteen devices with Wide SCSI.

SCSI is an intelligent, peripheral, buffered, peer to peer interface. It hides the complexity of physical format.

DIAGRAM OF SCSI


SCSI CONFIGURATION A SCSI-controller, which is usually integrated into a SCSI device, connects the SCSI device to the SCSI bus.

SCSI devices are classified as initiators and targets.

An initiator (e.g. SCSI host adapter) triggers a task on the SCSI bus and the target (e.g. SCSI controllers on hard disk drive , CD-ROM drive) carries out on the task. Some Devices as both initiator and target.

The original SCSI allows eight devices to interface to the SCSI bus.

A unique SCSI ID between 0 and 7 is assigned to each SCSI device on the SCSI devices.

The IDs are usually set using jumpers or switches on the SCSI adapter board and the SCSI devices. The first host adapter on the SCSI bus is normally given the SCSI ID 7 and the other adapters on the bus.

The ID for the first SCSI hard disk drive on the bus is set to 0 and for the second drive the ID is set to 1.

The SCSI adapter supports the plug and play (PnP) mechanism, then the configuration of SCSI devices could be automatic.

SCSI supports interfacing of initiators and targets in any combination.

C

PC

BU

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ID 0(Device)SCSI Bus

SC

SI C

ontro

ller

SC

SI C

ontro

ller

ID 1(Device)

SC

SI A

dapt

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ID 7

COMPUTER

SCSI Configuration

SCSI VARIATION

There are three different SCSI variations. SCSI-1

SCSI-2

SCSI-3

SCSI-1 The SCSI-1 was standardized in 1986.

The SCSI standard published by ANSI , as are the ATA standards. SCSI-1 uses an 8 bit bus, and supports data rates a 5 MB/s and connects up to 8 devices.

SCSI-1 inspired the work that has led to today’s SCSI standards.

SCSI-1 devices need not understand the Common Command Set.

SCSI-2 SCSI-2 is an improved version of SCSI-1. At the same time, SCSI-2 added optional higher speed transfer modes. At the hardware level , SCSI-2 starts with the same parallel interface first used with SCSI-1.

SCSI-2 edit several new performance option. The combination of revised timing and synchronous data transfers allows for transfers of 10 MB/s.

SCSI-2 also made some of the origin SCSI option.

This is most useful for multitasking.

FEATURES OF SCSI-2 Fast SCSI

Wide SCSI

New cables

Additional commands

Active termination

SCSI-3 SCSI-3 allows data transfer rates up to 20 MB/s and up to 32 SCSI devices with 32-bit wide.

The 16-bit wide SCSI is implemented with a single p cable.

The SCSI-3 is termed as Ultra SCSI ,Fast-20 SCSI ,or Ultra SCSI-3.

The 16-bit version is called as Wide-Ultra SCSI or Wide Fast-20 SCSI and has up to 40 MB/s data transfer rates.

It supports up to 32 devices with 32-bit wide data bus.

COMPARISON OF SCSI VARIATION

Variation Name Transfer Rate

(MB/s)

Bus Width(Bits)

Bus Length(Meters)

DevicesSupported

SCSI-1 SCSI-1Wide SCSI

510

816

63

816

SCSI-2 Fast SCSI Fast Wide

SCSI

1020

816

33

816

SCSI-3 Fast-20 SCSIWide Fast-20

SCSI

2040

816

1.53

84

ULTRA & ULTRA WIDE SCSI Ultra SCSI delivers 20 MB/sec over the 8-bit bus.

Ultra-wide SCSI incorporates the 16-bit bus, and the speed raises to 40 MB/sec.

Ultra SCSI offers the potential of connecting as many as 15 devices to a single port.

SCSI HARDWARE The hardware that comparises the SCSI bus consists basically of a host adapter , some cables , and the actual devices connect to the bus.

Some of the factors we should consider when evaluating SCSI hardware are as follows:

Performance level

Connectors

Cables

SCSI HOST ADAPTER The host adapter is the brain of the SCSI bus.

The computer sends to the adapter all of its requests for access to the SCSI devices.

The adapter translates the requests to the appropriate SCSI commands and transmits them to the correct device.

The adapter then receives the responses to the commands from the devices.

Selecting the right host adapter for our needs is an essential part of building an effective SCSI bus.

Adapter range in features from low-priced cards designed to connect a single device to a PC such as PC.

SCSI HOST ADAPTER


Manage all devices on SCSI bus.

Support internal and external SCSI devices.

Host Adapters is the soul of SCSI system.

Form a single daisy chain with devices.

FEATURES OF HOST ADAPTOR

SCSI CONNECTORMore than any other standard PC wiring system , SCSI suffers a plagueof connection. Not only do internal and external devices use different connector styles, but both come in wide variety.

There are separate internal and external connector styles, the system also suffers from generation differences.

Internal Narrow-Bus(Internal SCSI Connector)

External SCSI Connector(A Connector)


INTERNAL NARROW-BUS The SCSI interface was the basic 50-contact pin connector used on the first SCSI drives.

This connector featured two parallel rows of pins in a rectangular array.

The pins separated at increments of 0.1 inch both horizontally and vertically.

All SCSI devices the eight-bit implementation of the standard use this connector.

EXTERNAL SCSI CONNECTOR External SCSI connectors has 50 pins arranged in two rows of 25 and just like an enlarged Centronics printer connector.

D-SHELL CONNECTORS Some older external SCSI devices and host adapter used 50-pin D- shell connectors with the same signal assignments as the A connector.

25-pin D-shell connectors saved space and were popularized by apply computer for its Macintosh equipment.

These connectors do not have enough connections for differential signals.

SCSI CABLE The SCSI bus are the cables used to connect the SCSI devices to the host adapter and to each other.

The SCSI bus can connect both internal and external devices to the host adapter.

MULTIPLE CONNECTORS ON THE SCSI BUS

PHASES OF SCSI: Phases is the name of the data transferred between the SCSI initiator and the target.

SCSI COMMANDS:- SCSI provides a number of commands for general transactions with the devices on the bus.

It can first get the IDs of devices present on the bus,and can query the types of devices.

Devices specific commands can be issued to gather more information.

A term used to describe the process of stopping a running software program or permanently removing a program from a computer.

When referring to SCSI, termination is a connector that's added to the end of a SCSI chain to let the SCSI bus know when to stop looking for devices

Three types of termination:-

Passive:- Passive termination uses a set of resistors.

Active:- This terminator has a voltage regulator that ensure the correct information voltage

forced perfect termination(FTP):- Even better than active termination.

SCSI TERMINATOR

TERMINATOR


ADVANTAGE OF SCSI The big advantage of SCSI cable is its device support .

SCSI peripheral devices are intelligent and independent.

A control is built on to each SCSI device. This allow the computer to do other work.

SCSI is fast(10 MB/s on 8-bit bus, 20 MB/s on 16-bit bus) .

It can take full advantage of multitasking capabilities of the SCSI bus. SCSI driver are, on the whole, more reliable than ATA/IDE device.

DISADVANTAGE OF SCSI SCSI has never been cheap.

There are three different port interfaces for connecting internal SCSI devices: 15 pin, 68 pin and 80 pin. We can buy adapters to convert from one kind of connector to another.

when something breaks, SCSI drives are more difficult to repair then ATA /IDE device.

There are even more interfaces for connecting external devices. We know of at least four. We can buy cables convert from one port interface to another.

Which Should I Use , IDE or SCSI ? IDE is basically used when there are one or two device available for attachment and SCSI used in vast Application where the no. of device are large.

IDE, EIDE, SCSI are interfaces which are used according to Application

SUMMERY

REFRENCES

”Hardware Bible” “Winn L.Rosch” “Techmedia”.

Complete PC Hardware.

“Govindrajalu” ”IBM PC & Clones” , TMH “2nd Edition”.

Internet References:

WWW.PCGUIDE.COM

http://www.pcguide.com/

http://www.pcguide.com/

THANK

YOU

presentation on various interfacing standards:-ata /eide, scsi

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