Not Heathkit related: Zilog PDS8000/MCZ hardware

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Les Bird

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Jun 9, 2021, 5:53:29 PM6/9/21
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Greetings all,

I've recently acquired 2 Zilog dev systems from an eBay purchase. These are heavy machines equipped with 2 8-inch floppy drives. The software that came with it looks to be in really good shape, 32 hard sector format (128 bytes per sector). My first task will be, if they work, to image the disks by adapting Dwight Elvey's H89LDR. Should be a fun project.

My very first programming job out of high school was on these very same machines so for me there's some nostalgia here. I also have disks for these machines from when I used to program them so hopefully I can image those as well, although they are not in the best of shape (some are bent).

The operating system is called RIO but with some mods these machines can also run CP/M but I'm not really interested in doing that.

One of the machines included a Z8000 4Mhz dev board with onboard RAM (I think 256K) but in the default configuration the machines come with a Z80 CPU board at 2.5Mhz.

The interface is via RS232 terminal to a card with 4 8251 serial chips.

The buss is NOT S100, it is a custom buss designed by Zilog specifically for these systems.

IMG_6098.JPG

Z8000 dev board
IMG_6091.jpg


norberto.collado koyado.com

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Jun 9, 2021, 7:23:57 PM6/9/21
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Nice enclosure for the H89-SBC and then connect both floppy drives to the H37 controller. 

Norberto

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Les Bird <les...@bellsouth.net>
Sent: Wednesday, June 9, 2021 2:53 PM
To: SEBHC <se...@googlegroups.com>
Subject: [sebhc] Not Heathkit related: Zilog PDS8000/MCZ hardware
 
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Glenn Roberts

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Jun 9, 2021, 10:18:45 PM6/9/21
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Really nice find Les. Have fun!

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Les Bird
Sent: Wednesday, June 09, 2021 5:53 PM
To: SEBHC <se...@googlegroups.com>
Subject: [sebhc] Not Heathkit related: Zilog PDS8000/MCZ hardware

 

Greetings all,

 

Z8000 dev board

image001.jpg
image002.jpg

George Farris

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Jun 9, 2021, 11:04:26 PM6/9/21
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Nice score Les,

I recall one of these at the place I worked, never layed my hands on it but it does look very familiar.

George

Glenn Roberts

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Jun 10, 2021, 5:41:54 AM6/10/21
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Curious whether there’s a solid state replacement for the 8” drives? Would gotek or SVD work? You’ll probably need that if you want to do anything serious with these machines.

Sent from my iPad

On Jun 9, 2021, at 11:04 PM, 'George Farris' via SEBHC <se...@googlegroups.com> wrote:


Nice score Les,

I recall one of these at the place I worked, never layed my hands on it but it does look very familiar.

George


On Wed, 2021-06-09 at 14:53 -0700, Les Bird wrote:
Greetings all,

I've recently acquired 2 Zilog dev systems from an eBay purchase. These are heavy machines equipped with 2 8-inch floppy drives. The software that came with it looks to be in really good shape, 32 hard sector format (128 bytes per sector). My first task will be, if they work, to image the disks by adapting Dwight Elvey's H89LDR. Should be a fun project.

My very first programming job out of high school was on these very same machines so for me there's some nostalgia here. I also have disks for these machines from when I used to program them so hopefully I can image those as well, although they are not in the best of shape (some are bent).

The operating system is called RIO but with some mods these machines can also run CP/M but I'm not really interested in doing that.

One of the machines included a Z8000 4Mhz dev board with onboard RAM (I think 256K) but in the default configuration the machines come with a Z80 CPU board at 2.5Mhz.

The interface is via RS232 terminal to a card with 4 8251 serial chips.

The buss is NOT S100, it is a custom buss designed by Zilog specifically for these systems.

<IMG_6098.JPG>


Z8000 dev board
<IMG_6091.jpg>



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Santo Nucifora

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Jun 10, 2021, 8:47:40 AM6/10/21
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Hi Les,

I have a similar system for Z80 development here:  http://vintagecomputer.ca/zilog-z80-development-system/

Unfortunately, I don't have any software for my system but I wish you luck with yours and your efforts.  I'll be watching with interest.

Santo

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/AC116B83-211E-47EB-AFE9-F2E9BD56ED48%40gmail.com.

Les Bird

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Jun 10, 2021, 2:07:22 PM6/10/21
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Santo,

That definitely looks to be identical but with some small differences. It looks like you have the Z80 cpu card and the floppy disk controller card. The slot configuration seems slightly different than what I have.

I will post my results for recovering the software here. My plan is to do what we did for the Heathkit computers using Dwight Elvey's h89ldr utility. It works like this:
1. You punch in a small program on the Zilog systems using the system debug monitor to send/receive disk images over a serial port.
2. On the PC you launch a utility to send/receive disk images to/from the Zilog computer.

I've studied the ROM of the Zilog and there are calls to read/write disks track-by-track so that's good. I just need to modify Dwight's assembly code to call into these ROM functions and send the data over an available serial port on the Zilog system.

For your Zilog system you'll need a 32 sector floppy disk in order to write the image and then boot from it.

If I'm successful I'll post the disk images on my website.

Les Bird

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Jun 10, 2021, 2:08:45 PM6/10/21
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Glenn, not sure if a solid state solution is available.

Would be nice if there was one though.

norberto.collado koyado.com

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Jun 10, 2021, 3:24:21 PM6/10/21
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The 8" floppy drives will work with the H89-Z37 that I build and Gotek drives should work as well. This is true only if everything is wired properly when using other controllers.

   

Sent: Thursday, June 10, 2021 11:08 AM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] Not Heathkit related: Zilog PDS8000/MCZ hardware
 

Les Bird

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Jun 12, 2021, 1:00:50 PM6/12/21
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Norby, that is a beautiful Z89-37 card design. Do you have any of these assembled to sell?

Also, after lots of debugging and mixing/matching boards/drives from both machines I finally got one system working and booting to the RIO OS. Video link below in case anyone wants to see these old machines boot.


Les

norberto.collado koyado.com

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Jun 12, 2021, 1:09:06 PM6/12/21
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Nice to see that you got the system running again, WOW!

I think I build two of them to have a spare. Let me check during the day. 

You can have it for the price of the controller, the GALS, and the OSC + shipping. 😊

Thanks,
Norby

Sent: Saturday, June 12, 2021 10:00 AM

Norberto Collado

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Jun 14, 2021, 1:32:37 AM6/14/21
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Hello Les,

 

Found my spare H89-H37 controller which I will sell to you to help out. As this board is using the originals PALS from the Heathkit board, so the cost will be just the Controller and the OSC + Shipping.

 

See attached picture and will send out Paypal invoice.

 

Thanks,

Norberto

 

From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of Les Bird <les...@bellsouth.net>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Saturday, June 12, 2021 at 10:00 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] Not Heathkit related: Zilog PDS8000/MCZ hardware

 

Norby, that is a beautiful Z89-37 card design. Do you have any of these assembled to sell?

 

Also, after lots of debugging and mixing/matching boards/drives from both machines I finally got one system working and booting to the RIO OS. Video link below in case anyone wants to see these old machines boot.

 

 

Les

On Thursday, June 10, 2021 at 3:24:21 PM UTC-4 Norby wrote:

The 8" floppy drives will work with the H89-Z37 that I build and Gotek drives should work as well. This is true only if everything is wired properly when using other controllers.

 

Image removed by sender.   

 

H89-H37-Controller.jpg

Les Bird

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Jun 14, 2021, 8:28:57 AM6/14/21
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Thank you Norberto!!


Les Bird

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Jun 25, 2021, 9:00:52 PM6/25/21
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Santo, I’ve made really good progress with my Zilog computers. I have a utility that will read the disks and create disk images of them. I’m starting the archival process now and putting all of the disk images here:


You can go there and follow my progress. The only caveat is that you need a system that can boot to the RIO OS in order to write images to a floppy disk, which kind of defeats the purpose of an archival system. Ideally you could download a disk image and then punch in code to receive the disk image on the Zilog system but I can’t seem to get low level writing on these systems to work just yet. Documentation for these systems is very sparse.

Still working on it…but making good progress.

Les

On Thursday, June 10, 2021 at 8:47:40 AM UTC-4 santo wrote:

Santo Nucifora

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Jun 26, 2021, 3:10:27 AM6/26/21
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Hi Les,

This is excellent progress.  Your software and documentation is great.  Thank you for uploading those and documenting your progress.  I will definitely be following along with great interest.  

The only other resources I am aware of are at Bitsavers just in case you are unaware of them.

Disk images are here in IMD format:  http://bitsavers.org/bits/Zilog/

Your board images are interesting as you have a similar Z80-MCB board but my MDC board is version 1 versus your version 2 and, of course, I have no other boards.  Anyway, I hope some of this additional information helps if you didn't know of it already.  

Santo


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Glenn Roberts

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Jun 26, 2021, 10:00:22 PM6/26/21
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The DREM device says it supports 8” floppy emulation.  Steven Hirsch has spoken very highly of this outfit.  They shut down shipment over the winter but now have a new design and appear to be shipping.  On the pricey side for the hobbyist but you get what you pay for I guess…

 

https://www.drem.info/home

 

 

Of course back in ’79 we thought $300 was a decent price for an H17 (100K) drive! that’s $1,182 in today’s $ 😊

 

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Les Bird

Sent: Thursday, June 10, 2021 2:09 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] Not Heathkit related: Zilog PDS8000/MCZ hardware

 

Glenn, not sure if a solid state solution is available.

image001.png
image003.png

Les Bird

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Jul 3, 2021, 4:03:35 PM7/3/21
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Santo,

Great news. My imager for MCZ computers is complete. You can now upload disk images to a system that has no bootable disk. Took a bit of digging to find out why it wasn't working like it should but I finally solved it this morning.

When you turn on the MCZ computer it boots to a ROM debug console exactly like a H89 computer does. From there you can enter hex code for a program and then jump to the start address of the program to run it. So what I did was first I wrote the imager program to run in the RIO OS without using any specific RIO OS functions - only using the built-in ROM functions. Once I got that working I dumped the hex code to a text file and made it part of the host software that runs on Mac, PC and Linux. From the host software you can "upload" the imager which basically types in the hex code byte by byte into the MCZ debug console and then it jumps to the ORG address of the imager program to start it. At that point the imager is waiting for commands from the host computer. As long as you have a 32 sector disk (by them on eBay) and a working Shugart 801 8" floppy drive you can now upload disk images to the MCZ computer via the console port and write them to a blank unformatted disk. I have working disk images on my website for RIO OS 2.06 and 2.2.

This is awesome news for the 3 or 4 people in the world that have these old Zilog MCZ computers!!

Les

Glenn Roberts

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Jul 3, 2021, 5:28:25 PM7/3/21
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Great work les. Even though not Heath I’m enjoying hearing about how you’re applying some of the techniques we’ve used on this new (to you) machine…

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Les Bird
Sent: Saturday, July 03, 2021 4:04 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] Not Heathkit related: Zilog PDS8000/MCZ hardware

 

Santo,

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