Hi Bob,

BL> I was still in trouble with the modified IDE card. What
BL> speed do these things run at?

Bloody Hell. Make up you're mind will you. Does it work or not ?

BL>  I ended up XOR'ing an inverted address bit 9 with bits 3 & 4. This
BL> inverts 3 & 4 for IDE (168 to 1FO) and passes the higher addresses
BL> unchanged, but although it worked, my test to backup a few megs of
BL> CD to floppy and run a compare failed.

BL>  XOR gates are slow. The CMOS 4070 I used at 5V is good for 120nS
BL> (about the same as 74L). I replaced it with a 74HC86 which does 20nS
BL> at 5V... and it works now. Going from 120nS (8MHz) to 20nS (50MHz)
BL> made the difference. How fast do these bloody CD-ROMs have to be?

Just a bit faster than a 4070  a 74LS would have worked okay.

BL>  It's bloody stupid! The CD ROM wouldn't run off the VESA card in
BL> Mode-4 because it was too slow, and then it wouldn't run with ordinary
BL> CMOS because it was too fast!

Yep.

BL> Anyway, *FINALLY* I've got the fucker working. Both hard drives run
BL> Mode-4 with 1500kb/s transfers, the CD-ROM is reliable, and I've got
BL> lots of extra ports to run my ACAD dongle.

Great. Now all you've got to do is document it so that we can sell
it in kit form :)

Cheers, Brenton
@EOT:

---