8-bit IDE

From: Richard Erlacher <edick_at_idcomm.com>
Date: Tue Apr 18 00:12:05 2000

Your assumptions, reasoning and conclusions are all quite reasonable,
Allison. The drive makers might have had a motive to include that mode back
in the early days of the IDE, when there was some small risk that the
interface might be seen as appropriate for use in an 8-bit architecture.
Those days are gone, however.

Nonetheless, since I'm actually wanting to design for that mode, at the cost
of having to find the hardware that supports it, and for the simple reason
that it makes for the most widely flexible, not necessarily universal,
adapter. It will allow me to put and IDE and a WD100x-05 board and a
SCSI/SASI bridge on the same adapter.

PC's are terrible for testing hardware, yet the S-100's and other boxes of
the day were not well equipped with the means to run tests on various
interface equipment. I've had a lot of stuff sitting for a long time. I'd
like to verify that it's working before I attack the larger task of
extracting at least seemingly useful work from the old clunkers.

It's really not hard to come up with general-purpose interfaces like these,
and the closer they are to a General Purpose I/O channel, the more likely
they are to be useful, at least with a minimum of alteration.


----- Original Message -----
From: allisonp <allisonp_at_world.std.com>
To: <classiccmp_at_classiccmp.org>
Sent: Monday, April 17, 2000 7:15 PM
Subject: Re: 8-bit IDE

> >This is described rather minimally in chapter 6 wherein the registers are
> >defined. There's an 8-bit enable bit which, when properly conditioned,
> will
> >cause the data port interface to transfer 512 bytes as bytes rather than
> >256 words. There are LOTS of ways to "fake" it, but I'm trying to
> determine
> >whether anyone has actually operated an IDE interface normally used in
> >16-bit mode in this obscure and, possibly, scantily supported mode.
> If you find a drive that supports it let me know. I never did and I have
> good
> list of drive to pick from.
> >What I want is information from people who've actually read the standard
> and
> >attempted to use a normally 16-bit drive in 8-bit mode. This is not
> >particularly easy with the existing hardware. I'll be surprised if
> >has built interface hardware that is actually capable of this. It's
> >possible, though.
> Actually 8bit mode is the desireable config. Just that it was deemed
> optional.
> figure it out, why would a PC vendor put in a mode that is inherently half
> the performance?
> Allison
Received on Tue Apr 18 2000 - 00:12:05 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:32:41 BST