[sebhc] H-8 question from a new list member.

[Lee Hart]

West, Ronald S. wrote:
> I am working on designing an IDE port for my H-8. I have found a
> few designs on the web that are not for the H-8 directly but can
> be used as a good start for the project (IDE connector pin outs,
> etc.).

> Has anyone heard of someone doing this with the H-8 or H-89 already?

The GIDE board was designed by a group in Germany, and I think they are
selling them for a good price. This is a tiny credit-card sized PC
board. If your H8 has a Z80 CPU board, you unplug the Z80, plug this Z80
into the GIDE board instead, and plug the GIDE board into the Z80
socket. It adds not only the IDE interface, but a real-time clock and
some other features. They have software for CP/M, though you have to do
some assembly language work on it yourself to suit your computer and the
IDE drive you use.

> will mount it and a small laptop hard drive (175MB) inside the H-8.

Of course, even 175 Mb is 10 times bigger than CP/M will handle. :-)

It might be more straightforward to add a SCSI drive. The Heath H47/H67
interfaces for the H8 basically were an early implementation of SCSI. A
number of people plugged in a small SCSI drive from an old Mac, and just
used the existing Heath H67 software to talk to it. As I recall, the
process is:

 - get an H47 or H67 interface board for your H8
   (or build one with an NCR 5380 or equivalent chip)
 - make an adapter cable to convert Heath's 40-pin SASI to 50-pin SCSI
   (basically a few wires need to be shuffled around)
 - connect a 10 megabyte or larger SCSI hard drive
 - use the Heath H67 Prep/Part utilities to format the hard drive
   (the stock Heath software can only format it as 10 megs, no matter
   how large the drive actuall is. Hacking is needed for other sizes)
 - use MAKEBIOS to make a Heath CP/M BIOS to support the H67

The process for doing this on an H89 would be somewhat easier, because I
already have a bunch of H47 and H67 I/O boards :-)

> The hard part will be the device driver. Have not written a device
> driver for HDOS in a very long time so hopefully it will all come
> back to me ;^D

I know the H67 driver existed for HDOS. If you can find it, it would
serve as an example.

Finally, it is my opinion that using a physical mechanical hard disk
isn't worth the trouble any more. You can get RAM and FlashROM cards and
chips so cheaply, and it is so easy to interface them that they have
become a far better mass storage solution.
-- 
"Never doubt that a small group of committed people can change the
world. Indeed, it's the only thing that ever has!" -- Margaret Meade
--
Lee A. Hart  814 8th Ave N  Sartell MN 56377  leeahart_at_earthlink.net

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