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JJR512

Question regarding IDE devices, channels, speeds, etc.

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If you put two different-speed devices on the same IDE channel (cable), for example an ATA/100 hard drive and an ATA/33 CD-ROM drive, does the slower device slow down the entire channel, or can the faster device still work at its maximum speed?

My theory is that they should both be able to work at their full speeds, since the controller cannot use both devices at the same time, therefore when the faster hard drive is being used, it's being used alone, so the slower CD-ROM drive shouldn't interfere with it.

I'm looking for confirmation of my theory or refutement of it, along with supporting facts and explanations. :)

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My guess is since IDE drives don't support disconnect, the channel runs the speed the drive occupying the event at the time. But I wonder if there is an overhead for master/slave?

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If you put two different-speed devices on the same IDE channel (cable), for example an ATA/100 hard drive and an ATA/33 CD-ROM drive, does the slower device slow down the entire channel, or can the faster device still work at its maximum speed?

My theory is that they should both be able to work at their full speeds, since the controller cannot use both devices at the same time, therefore when the faster hard drive is being used, it's being used alone, so the slower CD-ROM drive shouldn't interfere with it.

I'm looking for confirmation of my theory or refutement of it, along with supporting facts and explanations. :)

With current IDE controllers you can run the two devices in different modes without problem. The bus is only driven by one device at a time, different speeds should not matter. That said I do know of an older VIA chipset (came in an IBM P3/533) which would hang when transfering data to two devices on the same channel in different transfer modes. Never seen this with Intel chipsets or current VIA chipsets.

Free

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