[sebhc] HDOS & IDE (was: H-8 question from a new list member)

West, Ronald S. RONALD.S.WEST at saic.com
Thu Apr 1 15:01:07 CST 2004

Jack (& others),

Thanks to all for the great ideas. 

I didn't know that the H67 was SCSI-like in its design. I have the H37/H67
board and will have to pull out the schematics and check that out. Will also
review the drivers for the H67 as that will answer a few questions. Like,
what sector size did they use & what disk size will HDOS 2.0 accommodate. 

If someone has used a 128k SRAM chip (I think that was Eric) for memory I
would be interested in which device was used. That might be something that
could be included on the eventual circuit board. Also, does anyone know if
the edge connectors are still available? 

I am also genning up a web page on my home server that I might be able to
post pictures on and schematics, source code, etc. When I get something
worth reading I will give out the IP address (which changes every 30 days or
so. Good old Verizon DSL).

I have one hurdle in my way at present. I zapped some diodes mounted on the
backplane last time I was playing with it. Plugged the zero-org board in
backwards. Yikes! Felt like a dufus what I did that, but its done so I won't
cry about it. It appears I will have to remove the backplane as those
components are mounted directly on it. Once that is done I will start bread
boarding and give some feedback on SEBHC as to my progress.

Was wondering about how to modify the ROM code to allow booting from the
eventual IDE interface but there may be a way to have the H67 boot code
detect the new interface and use it instead of the H67. Will look into that.
Getting a bit ahead of myself here. Need to fix the old workhorse first.


-----Original Message-----
From: sebhc at staunch89er.com [mailto:sebhc at staunch89er.com] On Behalf Of Jack
Sent: Thursday, April 01, 2004 1:08 PM
To: sebhc at staunch89er.com
Subject: [sebhc] HDOS & IDE (was: H-8 question from a new list member)

This is a great idea, and something I was considering as well (though more
in the role of "facilitator" rather than designer; I get lost pretty quickly
once I'm done to the component level). The FLEX user's group just did
exactly this, but in SS-30 format for the 6809. Schematics and driver source
are available; if you don't have access, let me know and I will forward info
to you. Using PCexpress, bareboard per unit cost was about $20.
As for partitions, what is the max drive size that HDOS will support? 
The other thing that I would like to see in a new form factor is the XCON
board for those of us still running 8080 systems. This raises the knotty
issue of copyrighted ROM code, but that's a question for another time.
And of course, if you're sticking a new board in the box, why not add a
couple SRAM chips and 32/64/128/whatever K of decent memory? My running '8
is using two 32K SRAMs sitting on about 1/8 of an otherwise bare prototype
You could do all this, including mounting a 2.5" laptop drive (or IDE flash
card) on a single full-size card and still have room left over!

"West, Ronald S." <RONALD.S.WEST at saic.com> 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.).

As part of this I will put the IDE port on a plug in board (the wirewrap
board) and will mount it and a small laptop hard drive (175MB) inside the

If all goes well I will have drives that show up as SY0, 1, 2, etc. and are
5MB or 10MB or so in size. It should speed up complicated compiles greatly.
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

Has anyone heard of someone doing this with the H-8 or H-89 already? Sure
would be nice to help shortcut the development time and get to other cool
stuff. I have some other ideas also but they all kind of hinge on getting
away from the old floppys that are slow and failing quickly.


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