ATA/IDE/EIDE TRANSFER MODES

I often used a combination of http://www.pcguide.com/ref/hdd/if/ide/modes.htm and http://www.ata-atapi.com/ as my definitive guides for ATA mode reference. However I got increasingly frustrated with having to flip between different pages to get the whole picture. So I made on big list. All information is pulled from the above two sites which I recommend you read in full because they contain a lot more information that just what's here. However, I hope this will serve as a nice quick reference for anyone who may need it.

Standard	Transfer Mode	Cycle Time (nsec)	Maximum Transfer Rate (MB/s)
ATA	PIO 0	600	3.3
ATA	PIO 1	383	5.2
ATA	PIO 2	240	8.3
ATA	DMA Single-word 0	960	2.1
ATA	DMA Single-word 1	480	4.2
ATA	DMA Single-word 2	240	8.3
ATA	DMA Multi-word 0	480	4.2
ATA-2	PIO 3	180	11.1
ATA-2	PIO 4	120	16.7
ATA-2	DMA Multi-word 1	180	13.3
ATA-2	DMA Multi-word 2	120	16.7
ATA-3	Same as ATA-2 - introduced SMART and Security	Same as ATA-2	Same as ATA-2
ATA/ATAPI-4	UDMA 0	240	16.7
ATA/ATAPI-4	UDMA 1	160	25.0
ATA/ATAPI-4	UDMA 2 ("UDMA/33")	120	33.3
ATA/ATAPI-5	UDMA 3	90	44.4
ATA/ATAPI-5	UDMA 4 ("UDMA/66")	60	66.7
ATA/ATAPI-6	UDMA 5 ("UDMA/100")	40	100.0
ATA/ATAPI-7	UDMA 6 ("UDMA/133")	??	133.0 (?)

NOTE: UDMA modes 0, 1, and 2 strongly recommend the use of an 80-conductor cable. To use UDMA modes 3 and up it is required that you use an 80-conductor cable. Note that 40-conductor cables and 80-conductor cables have very similar interfaces, thus a 40-conductor cable will work with a UDMA 3 or higher drive -- but it will drop to UDMA 2. For more information on 80-conductor cables see this page.

A few points on names used. The following are not official names, and in most cases aren't even used correctly - but they are often used in advertising to make things sound cool. Make sure you're not fooled!

IDE was a term made up by Conner Peripherals, Compaq and Western Digital to refer to ATA.
EIDE was a term used by Western Digital to help market ATA-2 drives - but they continue to use the term EIDE to refer to their current products.
FASTATA and FASTATA-2 were more marketing BS used by Seagate and Quantum to counter the EIDE hype from WD.
Ultra ATA was a name that companies started to use to refer to ATA-4 drives that supported UDMA-2 (UDMA/33), but has also been used to refer to UDMA-4 (UDMA/66) drives as well.

And two more points for Windows 2000 users:

UDMA/66 is NOT enabled by default in Windows 2000. Here is MS's KB article on how to enable it.
UDMA/100 is NOT supported by Windows 2000 prior to Service Pack 2. Here's MS's KB article on the available fixes.

Lastly, a similar chart for SCSI can be found at PC Guide here - their main SCSI page is here.

This page is © Phil Dibowitz 2001 - 2004