Simple ATA question

Yep.

Though you really won't see the difference between ATA133 and 100.

When you put a CD or DVD drive on the cable with your harddrive as a slave, or as a master on the second channel off the ATA card, does the optical drive affect the ATA bus speed for your harddrive?

On the same channel, yes. On the second channel, no. IIRC, optical drives are only ATA66.

Resurrecting my old thread here because I just found this very informative Wikipedia page about PATA. About two thirds of the way down the page it discusses "Two devices on one cable - speed impact," where, if I'm reading it right, it says that there actually is no slowdown of speed to either device's capbilities on the same cable. The slowest device does not determine bus speed. Slowdowns that do occur happen because of the one device at a time factor. If only one of two devices is being addressed, then there is no slowdown of that device's capabilities even with the slower device connected on the same cable. Have two devices being addressed simultaneously and the faster device is constantly waiting for the slower device to finish its round. Don't ever put those optical devices on the same channel as your hard drive unless you're ready to do some waiting in two device addressing situations. That's why most PATA computers have two ATA channels.

I still love my SCSI setups where none of these questions and problems apply.

Err, yes, but maybe there are no "simple ATA questions" ;-) Optical drives connected to the same bus as a hard disk reduce ATA performance, but if you really want to kill a PC install an ATAPI Zip drive. Poll, crawl, poll, crawl etc.

Yes, if how I read the Wikipedia entry is correct, then it shouldn't matter most of the time if there was an optical, including a zip drive, on the same channel. Only on those short moments when you're using one of the drives, which for myself, is pretty rare. But that goes against conventional wisdom, so what's the truth? Even when you're not using an optical drive, isn't the computer still addressing its existence, the same way in Classic having too many aliases in the Apple Menu was supposed to slow things down because the computer was constantly acknowledging the presence of those aliases?