why do udma 100 cables exist?

[forget that]

Since each ide port on a mobo can only access one device at a time and about the max speed a hard drive can give info to your computer is 60 Mb/s, a udma 66 cable should be all you would ever want.

[Jon]

ATA66 and ATA100 cables are the same thing. There are two types of IDE cables. 40 wire (UDMA33 and below) and 80 wire (UDMA66 and above).

[forget that]

"ATA66 and ATA100 cables are the same thing."
I disagree. The udma 100 cables are made with thermal plastic olefin while udma 66 cables are made with pcv.

that is why they sell ata 66 cables here:
http://cableclub.com/view_product.asp?item_no=20430

and ata 100 cables here:
http://cableclub.com/view_product.asp?item_no=20440

if they were the same they wouldn't be put into different catergorys and different bins at computer stores.

[Jon]

First time I've heard of a piece of plastic determining an ATA standard.

I'd like to see some white papers on this. Have some other than a retailer trying to make a buck?

[forget that]

it isn't just some retailer, I've see it in stores. I've even seen the different udma 100 cables. and that isn't the only place you can find them.

[Jon]

The difference in the cable is the number of wires...nothing more, nothing less. If they sell them at different prices, then that is why they do it...making a buck off of those that know no better. If they don't change the prices, then they may not know any better themsleves. One could quite possibly be a better grade cable than the other, but that would be the only other logical reason for them seperating the two. If it has 80 wires, it's UDMA66/100/133...if it has 40 wires, it's UDMA33 or less. End of story.

[forget that]

"One could quite possibly be a better grade cable than the other, but that would be the only other logical reason for them seperating the two. "

that was what I was thinkin, but then again they are the same price at that store.



Maybe the udma 100 cables made with the TPO can be 36 inches long, while the udma 66 cables can only be 18 or 24 inches long. ?....?

In any case I still have no idea why udma 100 cables exist.

[Jon]

That is very possible. It used to be that ATA cables could not extend beyond 24in. I have seen them 36in in very few places so it could be the type of cable being used as determining the reason for them being different. Is the only reason I can think of.

[RainMaQer]

On that site the "66" comes in different lengths upto 36 the same for the "100"... but there does seem to be other differences between the two... they look only cosmetic and/or quality based... but I don't think they should lable the one to only go to 66... I'm more than sure that the one they say is only 66 would work just fine for ATA100 drives... Just my $0.02

[Jon]

Originally posted by RainMaQer
On that site the "66" comes in different lengths upto 36 the same for the "100"... but there does seem to be other differences between the two... they look only cosmetic and/or quality based... but I don't think they should lable the one to only go to 66... I'm more than sure that the one they say is only 66 would work just fine for ATA100 drives... Just my $0.02

If it has 80 wires, I have no doubt it will.

[forget that]

well since the max throughput for a faster ata drive is about 50 Mb/s, I'm tryin to think of reasons why.

I have been talkin to people here:
http://www.amdmb.com/vb/showthread.php?s=&postid=624481#post624481

and here:

http://www.community.tomshardware.com/community/showflat.pl?Cat=&Board=comp_hdd&Number=261847&page=0&view=collapsed&sb=5

some guy just said "compression" with no explanation at all. the other guy couldn't figure it out.

another guy at tomshardware said something I think is partially wrong:
"Another thing is that IDE and independent device timing, so it's able to access the drives on the cable simultaneously."

well my conclusion is...

Udma 66/100 cables = normal cables

udma 100/133 cables = quality cables

but all 80 pin ata cables do the exact same thing.

the real difference is the ata 100 or 133 interface, where I believe a max of 133 MB/s coming probably from 3-4 hard drives in a raid setup all on their own ide chain can send a max of 100 or 133 MB/s to the rest of the system.

[forget that]

and a little off topic but if I have an ata 100 hard drive as the master and an udma 33 dvd drive as slave on the same ide chain either:

a. the ata hard drive will be forced to run at udma 33 speeds, because the dvd drive interface is only ata 33

or

b. they will both run at max speed because I'm using a udma 66/100 cable and both drives are accessed only at seperate times because the ide chain can only access one device at a time.


so is it a or b?

[touser]

Originally posted by forget that
and a little off topic but if I have an ata 100 hard drive as the master and an udma 33 dvd drive as slave on the same ide chain either:

a. the ata hard drive will be forced to run at udma 33 speeds, because the dvd drive interface is only ata 33

or

b. they will both run at max speed because I'm using a udma 66/100 cable and both drives are accessed only at seperate times because the ide chain can only access one device at a time.


so is it a or b?
Both drives will run at their maximum speeds unless they are writing from one to another on the same ide channel. :)

[Dabljuh]

How sure are you about that?

I often heard the oppositve, especially with CD/DVD drives - "Thouh shalt not put them together with HDDs on the same channel"

[Shadow ÒÓ]

that is a common misconception that I believed too once. To test it, simply run some benchmarks. Run Sandra or something on the drive solo, then plug in a slower device and run it again. You'll see no change.