8-bit IDE

From: Richard Erlacher <edick_at_idcomm.com>
Date: Tue Apr 18 10:07:34 2000

plz see comments below.


----- Original Message -----
From: <allisonp_at_world.std.com>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, April 18, 2000 7:27 AM
Subject: Re: 8-bit IDE

> On Mon, 17 Apr 2000, Richard Erlacher wrote:
> > Well, I've got one drive, an ST351, I think it is, that responds to the
> > 8-bit conditioning. It's a 1.25"-tall 3-1/2" drive, of 44 MB capacity.
> > That's not what I want for the "hard-card" on the S-100.
> I have two of them. Never thought to try them as they are slow and very
> old.
... and they're of about the right capacity for an old-style CP/M setup, if
you want to be true to the period. They make the typical
parallel-port-driven SMD or other setup typical of the 1976-1981 timeframe
look pretty bad, though.
> > All your assertions about the relative folly of expending
> The 1003 was never useable in ISA-8 (xt bus).
That's understandable since the IOCS16- is on the C-D connector. The
missing bit, BTW, is probably not on the 'WAH board, and it's SET for 8-bit
mode in the IDE standard. If you only use A-B, you won't see it and, by the
way, neither will the ISA bus, hence its standard (only because almost
everyone faithfully copied IBM) logic for steering the bytes in that
signal's absense, would try to shuffle the outgoing bytes into an 8-bit
window on the A-B connector only. On reads, you'd be in trouble, since half
the bytes would be missing. The ISA bus' response to IOCS16- is to enable
the high-order bus buffers on the little C-D connector.
> What I did do instead was to use a WD1002WXA to make that interface
> as it was already ISA-8 and easy to interface as a 8-bit controller.
> Wrote an article for TCJ about it.
I have one old data book from WD that has some of the XT-type controllers in
it, but lacks that one. What are the characteristics of this one?
> Allison
Received on Tue Apr 18 2000 - 10:07:34 BST

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