YDL install problems on a B&W G3

[Geoffrey S. Mendelson]

On Thu, Feb 24, 2005 at 10:41:10PM -0800, Daniel Gimpelevich wrote:
> You did mention that you tried putting the CD drive on the IDE connection
> on the motherboard, but you failed to mention which IDE connection on the
> motherboard you used (there are two), so that was still the most likely
> cause. However, if Cmd-Opt-O-F (not Ctrl-Opt-O-F) fails to bring up OF,
> the machine might not be registering your keystroke on boot. Evidently
> this can happen on the B&W even with the stock keyboard. Some people have
> had better luck with ADB keyboards. Did the Darwin CD boot by you typing
> "boot cd:,\\:tbxi" in OF, or by another method?

Another problem with the B&W G3's is that there are two versions of the
motherboard. Version 0, as it was later called had problems with the
IDE interface. The first interface could only support a master drive,
slave drives did not work. Both of them could not support high speed
DMA transfers, although they would do them.

The result was random data corruption on the read side. The problem was
known for a long a time and MacOS 8 and 9 third party drivers fixed
it by forcing the drive to slow DMA mode. OS X up to jaguar (10.2)
included a similar fix in it's disk driver, but it was not carried
over to panther (10.3) and AFIK it never appeared in Linux.

The corruption occurs on any fast drive, and the largest IDE drive that
was slow enough was a 20gig Maxtor, but by the time 20gig drives became
popular, they were two fast. About the bigest drive you can use and be sure
is a 12 gig Apple.

It also affects the second channel too. ZIP drives are too slow to have
problems along with the original Apple CD ROM drive. A DVD drive in DVD
playback mode is slow enough, but a higher speed DVD drive or CD DRIVE
(more than 16x CD or 4x DVD) is too fast.

The workaround is to buy an extra IDE or SCSI controller and abandon the
one on the motherboard. These cost about $75 on EBAY which is IMHO about
what the machine is worth. 

In some ways it's sad, because these are real workhorses, but by the time
you upgrade the hard drive, buy a new IDE controler for them and more memory,
you've just about bought a Mac mini.

Geoff.


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