ISA bus throughput
ard at p850ug1.demon.co.uk
Thu Feb 2 13:18:53 CST 2006
> It's no news that cd-roms could operate in older
> machines. I remember a friend with a Tandy 1000
> something years ago who had one hooked up (can't
> remember if it was internal or external though). And
> he could listen to music while he was doing
> *presumably* something useful with the machine.
Most older CD-ROM drives had built-in DACs and thus an audio output. You
could use that to play a music CD without using any of the host
computer's CPU cycles at all (the external Philips I have has
play/stop/skip track controls on the front, it can be used as a simple
audio CD player without connecting it to a computer).
There was often an audio connector that you linked to your soundcard,
but that just fed into the mixer stage of the soundcard. Again no host
CPU cyclers were needed.
> It would be nice to obtain a schematic of one of the
> more primitive IDE cards *whistles*. And wouldn't
I did trace out the schematics of the one in this machine. To be honest,
it was totally trivial. A few buffers and a PAL. I would thoink you could
design one by reading the IDE spec/
> artwork be nice too ;). Would an 8-bit card take the
> place of a 16-bit card in an AT? Presumably yes,
> albeit slower I guess. The Acculogic sIDE/16 or
Most IDE drives expect a 16 bit data bus, at least for the data register.
The 16 data lines from the drive are buffered and fed to the 16 data
lines on the ISA slot.
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