8-bit IDE

From: Richard Erlacher <edick_at_idcomm.com>
Date: Sun Apr 16 18:04:18 2000

Frankly, the reason I'm exploring this is because with the 8-bit mode, I
don't have to buffer the data at all beyond the on-board data-in and data
out buffers at the bus interface. The board I'm using to host the thing is
one equipped with buffers on the low-order address, data in, and data out.
It also produces a suitable select, read, and write strobe. If I were
willing to add any components at all, which would be the case if I had to
use the 16-bit interface I'd certainly not fiddle with the TTL MSI. I'd be
inclined to use a CPLD since they can drive the cable.

>From what I read in the standard, this is a normally selectable operating
mode for the interface. What's more, only the smallest of drives would be
appropriate for CP/M on the S-100, since CP/M supports, at most, 120 MB, and
that only at the expense of having any FDD's. I've got floppy drives that
handle that much. Back when I used CP/M every day, I owned the largest hard
disk system on CP/M that I'd ever seen, at 44MB.

I bought a 15 GB drive this afternoon that cost only $99. The small
notebook drives should cost about $5-10, which is acceptable. Clearly,
lower capacity drives, less common, of course, would probably cost about
that much as well.


----- Original Message -----
From: John Wilson <wilson_at_dbit.dbit.com>
To: calassic computer mailing_list <classiccmp_at_classiccmp.org>
Sent: Sunday, April 16, 2000 10:21 AM
Subject: Re: 8-bit IDE

> On Sun, Apr 16, 2000 at 08:18:51AM -0600, Richard Erlacher wrote:
> > Has anyone on this list dealt directly (not through the BIOS) with 8-bit
> > IDE drives of 2-1/2" size? ... Any size at all?
> No, I haven't heard of any 8-bit IDE models since the very ancient Seagate
> ST___X drives. But I gotta ask, why even bother looking for them, when
> using a 16-bit IDE drive on an 8-bit bus is *SO* easy? Two 373s, a 244,
> a 245, and a PAL for the selects (plus a flip-flop if you want to be cute
> and have the even and odd bytes go through the same I/O port address).
> And then you can use any old drive, no need to get addicted to rare
> John Wilson
> D Bit
Received on Sun Apr 16 2000 - 18:04:18 BST

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