UMDA ATA100 ULTRA ATA... is there a difference?

[Lumax]

Well, obviously there are performance differences but what I'm wondering is if I buy a Mobo with a UMDA interface can I plug an Ultra ATA 100 Hard Drive into it?

[Tinnax]

Do you mean UDMA? Or UMDA? Because UDMA refers to speed. Like UDMA 3-5 or so, for IDE hard drives (the regular sort).

ATA 100 is, in fact, UDMA 5. Confusing, since ATA stands for the standard used. 100 refers to the rate of transfer, in this case 100 Mb/s. ATA is an older 'descriptor', but often the terms are used interchangaebly.

A mobo that comforms to UDMA5 standards is backward compatible to ATA 100 and below, since in essense, UDMA5 is ATA 100. To make things even more confusing, you will see it listed as ATA 5 instead of UDMA 5. Or as above, Ultra ATA 100, which makes it even more confusing.

To reiterate:

ATA is specification number, UDMA is direct access to memory, they are almost interchangable.

ATA-5 = UDMA100 =100Mb/s -transfer speed from disk to memory
ATA-6 = UDMA133=133Mb/s- transfer speed from disk to memory.

As an example, here's a PCI card to add another IDE slot to your computer. If you look at the specs, it covers all the standards available for IDE to date.

This pci card here (http://www.newegg.com/app/ViewProductDesc.asp?description=16-102-002&depa=0)

[Lumax]

Ah cool thanks!

My concern was that one of the mobo's I'm looking at buying had UDMA listed as its IDE interface and I know my hard drive is Ultra ATA and I wasn't sure if there was going to be a compatibility issue. Sounds like I should be good to go though.