40 wires vs. 80 wires

[Keenath]

I recently got a new computer. This mainboard supports Ultra DMA, as does the hard drive. I also got a DVD-ROM... I would assume a newer technology like a DVD would almost always support Ultra, though I don't know for sure without looking it up in the docs, which I don't have at the moment. This brings up a few questions, though...

1) How can I be sure my OS (Windows 98 SE) is taking advantage of the extra speed? In the Guide it says I have to tell it to, but how do I know? Is it simply determined by the driver? I know the bios supports it and has it turned on...

2) Would it be better to plug the HD into the 80-conductor line and have the DVD on the standard 40-wire line, or to put the DVD in as slave on the Ultra DMA?

3) Would it be to my advantage to go ahead and put the DVD on an Ultra DMA cable, or is the physical limitation of a spinning CD going to eliminate any speed advantage the cable would give? In other words, does it actually matter if a DVD-ROM is on Ultra DMA or not?

I assume that, like an audio CD, the "DVD player" function will be totally unaffected.

Thank you for any input!

[BigBlue66]

Hey,

Not real sure of all the answers, although I do know that for any component that is ultra DMA capable, it has to be connected with the 80-conductor cable. Otherwise, it will work in a lower transfer mode.

Your idea of connecting the DVD as slave might work. At any rate, whether you hook it up as slave or on the secondary ide, make sure to use the 80-conductor cable.

Get back to us and let us know how it's going.

Cheers,

Big Blue 66

[BigBlue66]

Hey Again,

Just read another post that mentions that if you put a CD-ROM on the primary IDE as slave, it will slow the HDD down. I can only assume that a DVD would do the same thing.

My advice from the prior post about using the 80-conductor cable still holds, but try to put the DVD on the secondary IDE.

Later.

BB 66

[kenja]

The 80-wire cable is only necessary for Ultra 66 (and now 100).

If I only had two IDE devices, I would definitely connect them to their own ribbon cable. That way, the (two channel) controller doesn't have to wait for one device's bits to be sent/ received before dealing with the other device.

Side note: The "official" specification for IDE cable length is 18 inches. Eighty-wire cables are also available in 24 and 36 inch versions. I've had good results using a 24 incher, but I think 36 inches might be asking for trouble with the higher "burst" rates.

[xor_chad]

Adding to kenja. If you use longer cables, often you will lose detection of the drive on boot. I used to make 2 and 3 foot cables and often had this problem(often as in once a week). Laters...

------------------
Chad Wilson
C++/ASM Programmer
PC Support Technician

[kenja]

Here's another item from the "Do as I say, not as I did!" department: The 80-wire cables are more delicate than the older style. Be careful about dragging them over the sharp edges that may lurk within a case.

Another thing: If you've only got one device on the cable, attach it to the end connector. Otherwise, the unterminated (but that's more of a SCSI term) end of the cable will be acting as an antenna. I'd guess the signals would also be reflecting back (somewhat).