Help Re ata100 on my mobo

[BIGJR]

Dear sir/madam,

I am looking to by a new mobo and I am looking at several models that have UDMA100 or ATA100 or whatever it is called. I am not sure if they are the same thing or both different? I would like to know:-

1. Which is the difference with the above or they both just a different name for the same thing?

2. If I get a mobo that supports ATA 100, can I use my UDMA 66 hard drive with it?

Help much appreciated.

Thanks

[MikeHof]

Yeah they are the same thing. It's backwards compatible so your 66 would work on it. I had the same question when I bought my mobo. http://www.sysopt.com/forum/smile.gif

[cntrowland]

Here the breakdown on UDMA/DMA, if you care to know some details http://www.sysopt.com/forum/smile.gif ...

"Older" hd's use PIO modes to transfer data from/to memory. Newer (and most current) hard drives now use DMA or Direct Memory Access. These "intellegent" drives skip the CPU and access memory directly, leaving the CPU free for other things.
These UDMA drives now ignore the PIO modes and transfer data using DMA modes 0-5.
DMA 0: 4.2mb/s
DMA 1: 13.3 mb/s
DMA 2: 16.6 mb/s
DMA 3 ("Ultra DMA") 33.3 mb/s
DMA 4 ("Ultra DMA") 66 mb/s
DMA 5 ("Ultra DMA") 100 mb/s

Modes 3,4 and 5 here are the same when referenced as ATA/33, 66 and 100, respectively. Today, ALL BIOS have support for these new modes, so you board will support it if you've purchased it recently at all. REMEMBER.... the fastest DMA transfer is still 33 mb/s... even at DMA 5! The rating of 100mb/s is only a MAXIMUM or PEAK rate. HAVE FUN!

[John Prophet]

One other tidbit to remember is that ATA33 uses a 40 pin cable. ATA66/100 uses an 80 pin cable. Although they BOTH use the same 40 pin connector,the ATA66/100 wont work with the 40 pin cable. The 80 pin cable has 40 extra wires used as a sort of shielding to better insulate the wires from each other. Im tempted to swap my 80 pin cable for a 40 pin to see if my bios shows my HD as ATA33 on boot screen. Im not sure if it auto switches or how it works.

[Dudster]

John... I'm pretty sure that the BIOS auto-switches the DMA mode. My old drive (10GB WD ATA66) was given to me and I just used it with a standard IDE cable. I was having some problems so as a longshot I tried an ATA66 cable. My problems remained but I then discovered that the drive was actually ATA66 http://www.sysopt.com/forum/biggrin.gif

[John Prophet]

Im more interested in the fact that I see my cdrom listed as ATA33. Is that what they all are, or does the ATA66/100 apply to cdroms, dvdsetc also.

[NDD]

Generally, all newer CD/DVD-ROMS are ATA33, since you don't really need more (anyway no CD/DVD-ROM can't do transfer of 33MB/s). The only exception I saw so far is Asus DVD-ROM 12x, which supports ATA66 (again, for no special reason, I guess).

Best Regards ...