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CompTIA A+ Lesson 3 Understanding PATA SATA SCSI

This night Lesson was about PATA , SATA and SCSi hard disks let we have a brief review on This 3 HDD .

PATA (IDE )

Paralle l ATA(PATA), originally AT Attachment , is an interface standard for the connection

of storage devices such ashard disks, f loppy drives, and opt ical disc drives in computers. The standard is

maintained by X3/INCITS committee. It uses the underlying AT Attachment (ATA) and AT Attachment Packe

Interface(ATAPI) standards.

The Parallel ATA standard is the result o f a long history o f incremental technical development, which began wi

the or iginal AT Attachment interf ace, developed f or use in early PC AT equipment. The ATA interf ace itself

evolved in several stages f rom Western Digitals o riginal Integrated Drive Electronics(IDE) interf ace. As a

result, many near-synonyms f or ATA/ATAPI and its previous incarnations are st ill in common informal use. Aft e

the introduction of Serial ATA in 2003, the original ATA was renamed Parallel ATA, PATA f or short.

Below you can see PATA (IDE) Connecto r cable which one o f them have 40 wires and other one have 80 wires

80 wires cable can increase data transf er speed Parallel ATA cables t ransf er data 16 bits at a t ime .
http://en.wikipedia.org/wiki/Parallel_ATAhttp://alighalehban.com/comptia-lesson-3-understanding-pata-sata-scsi/http://alighalehban.com/


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PATA (IDE) C abl e 40 , 80 Wires

PATA (IDE) on Mainboard

Master &

Slave

Configuration in PATA

(IDE)

A drive mode called cable

selectwas described as

optional in ATA-1 and has

come into f airly widespread

use with ATA-5 and later. Adrive set to cable select

automatically conf igures

itself as master or s lave,

according to its pos ition on

the cable. Cable select is

controlled by pin 28. The

host adapter grounds this

pin; if a device sees that

the pin is grounded, it

becomes the master device;

if it sees that pin 28 is

open, the device becomes

the slave device.


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This set ting is usually chosen by a jumper set ting on the drive called cable select, usually marked CS, which

separate from the master or slave setting.

Note that if two drives are conf igured as masterand slavemanually, this conf iguration does no t need to

correspond to their position on the cable. Pin 28 is only used to let the drives know their pos ition on the cable

it is not used by the hos t when communicating with the drives.

With the 40-wire cable it was very common to implement cable select by simply cutting the pin 28 wire between

the two device connectors; putt ing the slave device at t he end of the cable, and the master on the middle

connector. This arrangement eventually was s tandardized in later versions . If there is just one device on thecable, this results in an unused stub o f cable, which is undesirable f or physical convenience and electrical

reasons. The stub causes signal ref lections, particularly at higher transf er rates.

Starting with the 80-wire cable def ined for use in ATAPI5/UDMA4, the master device goes at the end of the 18

inch (460 mm) cablethe black connectorand the slave device goes on the middle connectorthe gray one

and the blue connector goes onto the motherboard. So, if t here is only one (master) device on the cable,

there is no cable stub to cause ref lections. Also , cable select is now implemented in the slave device connecto

usually simply by omitting the contact f rom the connecto r body.

Direct memory access(DMA) is a feature of modern computers that allows certain hardware subsystems

within the computer to access system memory independently of thecentral process ing unit (CPU)

PATA (IDE) transfer modes and Rates : There are 4 common transfer mode in PATA Hdd which based

on each of these modes our device will have diffe rent Trabsfer Rate

1. Programmed input/output (PIO )

2. Single-Word DMA (WDMA)

3. Multi- Word DMA (WDMA)

4. Ultra DMA
http://en.wikipedia.org/wiki/WDMA_(computer)http://en.wikipedia.org/wiki/WDMA_(computer)http://en.wikipedia.org/wiki/Programmed_input/outputhttp://en.wikipedia.org/wiki/Direct_memory_access


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SATA

Serial ATA(Advanced Technology Attachment) (SATA)is a computer bus interf ace that connects host bus

adapters to mass storage devices such as hard disk drives and optical drives. Serial ATA replaces the older AT

Att achment standard (ATA later ref erred to asParallel ATA or PATA), o f f ering several advantages over the o lde

interf ace: reduced cable size and cost (seven conducto rs instead of 40), native hot swapping, fas ter data

transf er through higher signalling rates, and more ef f icient transf er through an (opt ional) I/O queuing protoco

Currently there are 3 revision of SATA Technology

1. SATA revision 1.0 1.5 Gbit/s 150 MB/s

2. SATA revision 2.0 3 Gbit/s 300 MB/s

3. SATA revision 2.0 3 Gbit/s 300 MB/s

4. SATA revision 3.2 16 Gbit/s
http://en.wikipedia.org/wiki/Serial_ATA


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SATA CABLE

SATA Conne ctor on HDD

SCSI

Small

Computer

System

Interface(SCSI)is a set of standards fo r

physically connecting and transf erring data

between computers and peripheral devices.

The SCSI standards def ine commands,

protocols and electrical and

optical interf aces. SCSI is most commonly

used f or hard disks and tape drives, but it

can connect a wide range of ot her devices,

including scanners and CD drives, although

not all contro llers can handle all devices.

The SCSI standard def ines command sets

f or specif ic peripheral device types; thepresence of unknown as one of these

types means that in theory it can be used

as an interf ace to almos t any device, but

the standard is highly pragmatic and

addressed toward commercial

requirements.
http://en.wikipedia.org/wiki/SCSI


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SATA Conne ctor o n Mainbo ard

SATA PORTS


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SATA Topo lo gy


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