On Apr 7, 23:31, Tony Duell wrote:
> Incidentally, is the ESDI spec
> available anywere (or at least a signal description)?
I'v not looked for whole spec recently, but the pinout is available at
http://www.u-net.com/mike/techref/iopin.txt (about 1/3 of the way down the
page) and also in "the hardware handbook" website at
http://www.hardwarebook.net/
However, you need to take a little care with some of the pinouts listed
there, as they're not all "official", some are just what people have found
to work in particular circumstances (eg, some of the "null modem" cables").
Didn't Aaron Finney have ESDI amongst his pinout list collection? And what
happened to that, anyway? His web page at
http://www.prinsol.com/classiccmp/ seems to have disappeared.
> > However, some PC controllers only support two drives (another legacy of
the
> > IBM PC BIOS) and of course they use drives 1 and 2. Therefore, some PC
> > manufacturers suggest using a cable with a twist, to swap pins 26 and
28
> > (DS1 and DS2), leaving the select jumpers the same on both drives.
I've
> > never seen a cable with a twist on a "real" ESDI system.
>
> I wondered about that, too (it was an obvious way for a twist to be able
> to swap drives 1 and 2). I assume from this that the drive select lines
> are not used as data lines for anything else, then (unlike SCSI, say,
> where the same 8 lines are used both to select a particular unit and to
> transfer commands and data).
No, it's a pretty low-level interface, like ST506/412. I read somewhere
that it was designed as an enhanced/faster ST412 interface, possibly by
Maxtor and Miniscribe, and I think Maxtor used to have some information on
their website. All I can find now, though, is a line in their glossary.
--
Pete Peter Turnbull
Network Manager
Dept. of Computer Science
University of York
Received on Sun Apr 08 2001 - 04:45:26 BST