road trip score: AViiON, Microdata 1600

Charlie Carothers csquared3 at
Fri Nov 26 12:25:36 CST 2010

On 11/26/2010 2:03 AM, jim s wrote:
> Do you recall any of the people at Microdata you worked with. I can name
> such as Max Malone, Al Weber, Chuck Canon.
Hmmm, I don't think I ever actually talked to anyone at Microdata.  The 
computer selection and company interface process all happened at a 
higher level than I was involved with at the time.
> The 821 firmware became the 1621, 1630, and later. I wrote and have a
> Disk system we called MPS that was written at the University of
> Missouri, Rolla for the 1621. We had a 5mb dynex drive, 2.5mb removable
> over 2.5mb fixed which the system ran on. It was very similar to CPM,
> but actually modeled after CPS on the IBM mainframe, and TSO.
Interesting.  We never had any "standard" peripherals interfaced to 
ours.  Ours was truly an "embedded" controller.  If it had been a few 
years later, I'm sure we would have used a Motorola 6800 or similar. 
Another group in the company was already using the Fairchild F8 in a 
product, but I think it was felt the F8 could not meet the processing 
> I still have the software and firmware, and have an emulator I have been
> working on to run the1621 code. I'd be interested if your friend with
> the diode boards still has any notes or materials from the firmware
> project.
I'm afraid I've completely lost touch with him, and I was not involved 
with his project at all.  At the moment I can remember his first name 
but not his last.  Since you say 1621 emulator I'm assuming you mean the 
higher level code and not the microcode.  Isn't it interesting with 
these machines how one must specify the code "level".  I'm sure there 
are other examples of this, but I've never personally encountered it 
other than with the Microdata machines.  BTW, I've always had a pipe 
dream of replacing the 800 microcode board with one containing RAM. 
That would open up some interesting possibilities I think!
> I have an 810 firmware in diodes. The diode boards run in both the 800
> and the 1600.
I'm pretty sure I have at least one discrete diode 820 firmware board as 
well.  I did not know the 1600 would run the same microcode.  I assume 
from that fact that the low level architecture in the 1600 is the same 
or possibly a super set of the 800's.
> As to your friend, the other thing that was interesting was that the
> micro assember would not only give you the object tape out, but it would
> give you a map of where to populate on the board, and a diode count if
> you wanted it to.
I'm guessing the micro assembler ran on a 360?
> I don't think I got the fortran cross assembler, or cross micro tools,
> but there was also a simulator on which you could do some checkout, all
> in fortran. The simulator on the mainframe was not interactive at the
> time, and not very useful.
It has been a very long time, but I seem to recall the 820 assembler I 
started with was written in Fortran ?? to run on an IBM 360.  For a 
variety of reasons we needed it to run on a Datacraft 6024.  For one 
thing, though the accounting department had a 360 it did not have a 
paper tape punch peripheral.  (I suppose I could have "punched" to mag 
tape on the 360 and then done a mag tape to paper tape copy on the 6024, 
but there were other issues as well.)  I really doubt that I have the 
source of the 820 assembler.  If I do, it is probably only on a mag tape 
which has been in the garage a lot of years.  I *might* possibly have a 
hard copy listing of the Fortran source code.  I'm sure I don't have the 
punched card deck that was my working source.
> There was one written which ran on the 1600 that was interactive, and a
> bit more useful. Sim1600.
I never used a simulator for the 820.  For development purposes we had 
an ASR33 interfaced to the 820 and a small debugger that lived at some 
dedicated place in core memory.  The debugger could also load the 
application from a higher speed paper tape reader.
> Jim

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