H8 8080 Boot process

[Jeff Albrecht]

In several recent threads initiated by me, with the help of this group, I got an H8 Z80 booting HDOS. Again, thank you.

This morning I'm trying to boot a different H8 that has an 8080 in it along with two 16k, and 2 8k RAM boards. I performed some of the same initial tests - for instance using the same drive used on the previous Z80 H8, I was able to start the drive motor using an OUT instruction.

Resetting I tried 'go' nothing. I entered memory 030 000 nothing not even the 'Pri  H   17' message in the FP.

Is there other boot routine addresses? Or longer routines that must be entered?

I do seem to recall something about an 'options board' or similar name / function. Is that missing from my system?

Suggestions?

c ya... - Jeff

[Glenn Roberts]

You must have an early ROM. It was only later that Heath added single key boot (the early ROMs were developed before the H17 existed).

To boot you must set the Program Counter register manually to 030.000 and then hit GO, so:

 

REG (decimal points light up...)

PC (the “F” key, same as PC)

ALTER (the “D” key; decimal points flash)

0 3 0 0 0 0

ALTER (decimals stop flashing...)

GO (the “4” key)

You should then hear the SY0: disk head and motor go...

You will only be able to boot HDOS since you don’t have the ORG0 card on that machine (the Z80 board has this built in).

Sent from my iPad

On Dec 9, 2020, at 1:13 PM, Jeff Albrecht <jeffrey.h...@gmail.com> wrote:

In several recent threads initiated by me, with the help of this group, I got an H8 Z80 booting HDOS. Again, thank you.

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[Jeff Albrecht]

On Wednesday, December 9, 2020 at 11:34:32 AM UTC-7 Glenn wrote:

You must have an early ROM. It was only later that Heath added single key boot (the early ROMs were developed before the H17 existed).

To boot you must set the Program Counter register manually to 030.000 and then hit GO, so:

 

REG (decimal points light up...)

PC (the “F” key, same as PC)

ALTER (the “D” key; decimal points flash)

0 3 0 0 0 0

ALTER (decimals stop flashing...)

GO (the “4” key)

Thanks Glenn, it booted HDOS. I put a reminder on my wiki pointing to this discussion.  

I quoted parts of your answer. If you have a website etc... that you would like me to link you name to let me know.

I guess I'll try the Zenith Z-37 next.

   - Jeff

[Glenn Roberts]

Great! I don’t maintain a web site (at least not yet). I mooch off others I suppose…

 

Without a soft sector controller board (as I recall from your pictures you only have two disk I/O boards – both the “H17” style) you won’t be able to do too much more than verify that the drives work.  they’ll still require hard sectored diskettes or the adapter … If they are double sided drives (which seems likely) there is a double sided mod to the H17 controller – you may already have that mod installed on your Z80 machine.  Others on this list are more expert on this than I

 

Heath marketed their soft controller board under the model WH-8-37.  A number of us are currently building out modern equivalents based on Norberto Collado’s latest creation

 

http://koyado.com/Heathkit/H8-H17-H37-H67-USB.html

 

with that you can interface to 3-1/2” floppy drives and do DS/DD/96tpi for over 700K of storage per disk.

 

 

 

 

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[Mark Garlanger]

With the BIOS-80 software under CP/M, the Z-37 disks can hold 400k per disk instead of 100k. There is also a HUG replacement driver for HDOS, to allow 400k disks too.

Mark

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[Glenn Roberts]

Right. The HUG replacement SY: device driver for the H17 controller board is on HUG disk 885-1095 which is in Les’ archive

 

https://sebhc.github.io/sebhc/software.html#HUG_Application_Library

 

As I understand it from the README, it supports double-sided drives but this requires the “extended configuration option” (a.k.a. “ORG0” card, a.k.a. HA-8-8) (or a Z80 CPU board I presume?).  It also supports 96TPI (80 tracks/side) drives.  So with DS/DD/96TPI drives and the HA-8-8 or Z80 board I believe you could do up to 400K per disk with just the basic H17 controller board… This is for HDOS.  As Mark says you’d need BIOS-80 on the CP/M side…

 

• Glenn

 

 

 

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