IMSAI 8080 replica

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Udo Munk

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Apr 15, 2019, 11:53:31 AM4/15/19
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For those who want to build an IMSAI 8080 replica follow @TheHighNibble via Twitter,
news and updates will be posted there.

Wesley Kranitz

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May 23, 2019, 3:27:29 AM5/23/19
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On Monday, April 15, 2019 at 10:53:31 AM UTC-5, Udo Munk wrote:
> For those who want to build an IMSAI 8080 replica follow @TheHighNibble via Twitter,
> news and updates will be posted there.

My first job was programming 8080 embedded controllers for process control. If I remember correctly, the construction article for the IMSAI 8080 was in Popular Electronics or Radio-Electronics. I will have to look as I have issues going back to the 60's.

Udo Munk

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May 23, 2019, 2:29:52 PM5/23/19
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On Thursday, May 23, 2019 at 9:27:29 AM UTC+2, Wesley Kranitz wrote:

> My first job was programming 8080 embedded controllers for process control. If I
> remember correctly, the construction article for the IMSAI 8080 was in Popular
> Electronics or Radio-Electronics. I will have to look as I have issues going back to
> the 60's.

That probably was the Altair 8800, the magazine issues with the construction articles
are available online nowadays.

The IMSAI 8080 came a bit later and was used by Gary Kildall to improve CP/M and
make it more modular. Steve Ness received the sources from Gary Kildall and we
used them to rebuild the OS from the sources for the machine.

During the 80's I wrote a Z80 emulation running on large UNIX RISC mainframes
to support embedded controller programming. Later I added an Intel 8080 emulation
and build virtual machines for running all the software from the 70's and 80's I
grew up with.

In the 90's I was using COHERENT to improve the Z80 emulation and build a VM that
can run all the DRI OS's. At MWC we played a bit with it too, most people at MWC
were familiar with the machines because MWC started with software products for
the S100 bus 8080 machines. We had not much time for this old stuff because
we were very busy with improving the COHERENT product.

Later I continued to improve the software, so that nowadays it is possible to run
it on 32bit micro controllers with similar performance I had with an Intel 386
running COHERENT. And with micro controllers it is possible to control the machine
with a front panel, so that it works almost the same as the original machine.

Quit interesting how this stuff was kept alive for more than 40 years now.

Wesley Kranitz

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May 24, 2019, 2:01:05 AM5/24/19
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Actually I think your correct. I have the original article. After that, We started using the Z80. We used a multiuser Z80 OS for development called Oasis. Our low level modules used Z80, but our Master controller used a 68000. I wrote a big chuck of the Z80 code, and Most of the 68000 Realtime OS. I loved doing that.

With respect to CP/M, I still have a number of Z80 S-100 bus boards from Cromemco and others. I played with CP/M a lot and had a system at home that had 8 inch Floppy's. Brings back a lot of memories...…...

Udo Munk

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May 24, 2019, 1:47:47 PM5/24/19
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On Friday, May 24, 2019 at 8:01:05 AM UTC+2, Wesley Kranitz wrote:

> With respect to CP/M, I still have a number of Z80 S-100 bus boards from Cromemco
> and others. I played with CP/M a lot and had a system at home that had 8 inch Floppy's.
> Brings back a lot of memories...…...

The current z80pack release also includes a Cromemco Z-1 emulation. The mainframe
is a modified IMSAI 8080 mainframe, but the system is filled with the Cromemco cards
from that time, ZCPU, FDC16, 7 x 64K RAM, TUART's and then some stuff. The emulation
is accurate enough to run Cromemco CROMIX, which is like COHERENT 2.x/3.x a
re-implementation of UNIX V7. Great fun to watch the Z80 running a multiuser
UNIX, one can see the systems heartbeat (timer interrupt) on the front panel LED's.

Anyone familiar with UNIX V7 or COHERENT won't have much problems learning
CROMIX, the manuals are OK to read.

Udo Munk

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Jun 26, 2019, 4:03:43 PM6/26/19
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The first batch of the IMSAI 8080 Replica kits was shipped and people start
building their kits. Feel free to visit https://groups.google.com/forum/#!forum/imsai8080esp
to see what some folks are doing.

If someone is wondering about the topic here, COHERENT played a significant role
for development of virtual Z80 systems during the 90's, the software from that
time is also included on the COHERENT VM's I've build.

Of course way back then I had no idea that this stuff would get so far, but I'm very
pleased to see how all this pieces of software I worked on over decades still is used
by others, who seem to have fun with it.

Thanks everyone for help, support, feedback and so on,
Udo

Udo Munk

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Jun 26, 2019, 4:28:50 PM6/26/19
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While thinking about it, not everyone reading this thread might by familiar with
the MWC history so let me add a bit about this.

Bob Swartz started MWC with a product for S100 bus machines like the IMSAI 8080,
that you can build as a Replica now. The product was YXBASIC, a BASIC interpreter
for Intel 8080 machines, mostly written by Steve Ness. Steve also provided the CP/M 1.3
source code he received from Gary Kildall. Of course it is possible to run all this
software on the IMSAI 8080 Replica system.

So also MWC played a significant role in these things going on now decades later.

Thanks to all friends and former colleagues @ MWC, it did make a difference in my life
working with you.

Udo
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