Today, the
ATA interfaces are the most commonly used interface on IBM
compatible computers to connect to computer hard
disk drives, CD-ROM drives, and other
types of disk drives. Each of the below standards are compatible
with each other, which means a new ATA drive can be used in a
computer using an older ATA specification. Finally, when a new
feature was introduced in an ATA standard, that feature is also
found in future releases. In other words, a ATA-4 is going
to have support for PIO modes 0, 1, 2, 3, and 4, even though these
were introduced in ATA-1 and ATA-2.
Below is a listing of each of the ATA, IDE,
and EIDE standards to help give user a better understanding of
the history behind this interface as well as an understanding of
each interface's capabilities.
ATA / ATA-1 / IDE
ATA is short for AT Attachment interface and also more
commonly known as IDE
or ATA-1. ATA was approved as a standard on May 12, 1994
under the ANSI document number
X3.221-1994. ATA was first developed by Control Data Corporation, Western
Digital, and Compaq. ATA-1 utilizes a
8-bit or 16-bit
interface, has a transfer rates of up to 8.3MBps,
and has support for PIO
modes 0, 1, and 2. Today, ATA / ATA-1 is now considered obsolete.
ATA-2 / EIDE / Fast ATA / Fast IDE / Ultra ATA
ATA-2, more commonly known as EIDE, and
sometimes known as Fast ATA or Fast IDE, is a standard approved by
ANSI in 1996 under document number X3.279-1996. ATA-2 introduces
new PIO modes of 3 and 4, has
a transfer rate of up to 16.6MBps,
DMA
modes 1 and 2, LBA
support, and supports
drives up to 8.4GB. Today, ATA-2 is now considered obsolete.
ATA-3 / EIDE
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-4 / ATAPI-4 / ATA/ATAPI-4
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 or ultra-ATA/33, which is capable of supporting data transfer rates of up to
33MBps.
ATA-5 / ATA/ATAPI-5
ATA-5 is a standard approved by ANSI in 2000
under document NCITS 340-2000. ATA-5 adds support
for Ultra-DMA/66, which is capable of supporting data transfer rates
of up to 66MBps, and has the
capability of detecting between 40 or 80-wire cables.
ATA-6 / ATA/ATAPI-6
ATA-6 is a standard approved by ANSI in 2001 under document NCITS
347-2001. ATA-6 added support for Ultra-DMA/100, and had a transfer
rate of up to 100MBps.
ATA layout
Each of the above ATA interfaces that are used with the 3.5-inch
disk drives have a 40-pin connector and are capable of supporting up to two drives per
interface. However, 2.5-inch hard disk drives utilize a 50-pin
connector and PCMCIA utilizes a
68-pin connector Below is an illustration of the ATA interface
Pin |
Function |
Pin |
Function |
| 1 |
Reset |
2 |
Ground |
| 3 |
Data 7 |
4 |
Data 8 |
| 5 |
Data 6 |
6 |
Data 9 |
| 7 |
Data 5 |
8 |
Data 10 |
| 9 |
Data 4 |
10 |
Data 11 |
| 11 |
Data 3 |
12 |
Data 12 |
| 13 |
Data 2 |
14 |
Data 13 |
| 15 |
Data 1 |
16 |
Data 14 |
| 17 |
Data 0 |
18 |
Data 15 |
| 19 |
Ground |
20 |
Key |
| 21 |
DDRQ |
22 |
Ground |
| 23 |
I/O Write |
24 |
Ground |
| 25 |
I/O Read |
26 |
Ground |
| 27 |
IOC HRDY |
28 |
Cable Select |
| 29 |
DDACK |
30 |
Ground |
| 31 |
IRQ |
32 |
No Connect |
| 33 |
Addr 1 |
34 |
GPIO_DMA66_Detect |
| 35 |
Addr 0 |
36 |
Addr 2 |
| 37 |
Chip Select 1P |
38 |
Chip Select 3P |
| 39 |
Activity |
40 |
Ground |
Related dictionary definitions
For additional information, please see each of the below
dictionary definitions for a brief definition as well as related
links and terms.
HARD DRIVE
FORUM
CH000695