Re: Restoring an S100 system

On Tue, 22 Dec 2009 17:34:08 -0800 (PST), gregg dot drwho8 atsign
gmail dot com <gregg.drwho8@xxxxxxxxx> wrote:

On Dec 22, 8:04 pm, Alli...@xxxxxxxxxxxxx wrote:
On Mon, 21 Dec 2009 19:37:20 -0800 (PST), gregg dot drwho8 atsign
gmail dot com <gregg.drw...@xxxxxxxxx> wrote:



On Dec 21, 6:46 pm, Herbert Johnson <herbrjohn...@xxxxxxxxx> wrote:
gregg etc. posted:

Hello!
I have here an S100 system who I believe was designed as a training
aid for I8080 assembler.

However when I attempted to start it,...nothing happened.
No lights on the front, and not even a gleep on the terminal screen.

What suggestions are available about restoring its power supply?

You have provided almost no information about what you have. Any
advice or info you get, will depend on  EXACTLY what you have. There
is no standard S-100 system, if you in fact have a "S-100" system; and
S-100 systems varied a lot anyway. What you can do to restore/repair
what you have, depends on your skills and tools plus docs plus
knowledge plus hints you get from others. That ALL depends on
identifying what you have.

Please describe the brand and model of your "S-100" system. If you see
a brand and model name/number on the power supply, please describe
that. If there are multiple boards in the box, please describe the
brand and model of those boards. Is "the terminal" part of the system,
does it work independently, ???? - brand and model please. Also,
please indicate if you have some skills in reading schematics,
soldering components, doing tests with voltmeters, etc.

(I'm not sure why my colleagues here are grasping at straws, trying to
GUESS what this person has and knows - instead of asking and WAITING
for his response. But it's wise to let this guy know there are LETHAL
voltages inside power supplies.)

Hello!
Actually gentlemen I do know a fair amount of electronics. However I
got started in this business well after the S-100 based systems
supposedly became museum pieces.

Can you do tests and repairs at the component level? Are components of
the 1970's and 80's something you know about? (BTW, one of your
respondents is a woman.)

Now as for your tips, that's next.

The other problem is that documentation on the old fellow does not
exist. I do know that everything is inside a standard chassis such as
the ones Altair and of course IMSAI used for their systems.

Again, there IS NO "standard S-100 chassis" either. Any S-100 system
can have any number of cards in it from any number of manufacturers.
The point of S-100 was to permit a variety of cards. As for "docs do
not exist", you might get some if you give brand and model info.

I also
have here the text by Artwick who describes in extreme sense how the
basic S-100 system was first wired.

"The text by Artwick"? Who? What text? I had to ask Google Books to
find it: "Microcomputer interfacing
 By Bruce A. Artwick, 1980" In any event, one S-100 book probably at
best only introduces you to what "S-100" means. It's a start, but it
won't help you fix your power supply.

I suspect I have an interesting experience ahead of me, next month.

The more info you provide, the better and more precise help you will
get. It's really that simple. But the first "tip" is: there are no
standards for S-100 systems, or for that matter 8080/Z80 systems. NO
STANDARDS - these are not IBM PC's, they don't have "standard"
features or architectures or chip sets or peripheral devices. It's
simpler to make no assumptions, and just determine what you have,
there in front of you, and work from that.

Herb Johnson
retrotechnology.com

Hello!
I understand Herbert, I really do.
Actually I am very familiar with the TTL logic of the '70s and '80s,
simply because three quarters of my collection of parts are indeed
from that period.

Now as for the system, based on what I was briefed about from the
fellow who sold it to me, the chassis is a basic S100 system box as
originally designed by the fellows behind the Imsai and the Altair
(even the thing from Heathkit). As for the guts of the thing that is
indeed next up. Over the next few days I shall be posting a series of
photos concerning each board. Plus one of its power supply. '

Now the important things. Someone who normally does not post but
simply visited the list and found out that I was interested in
something like that.
He bought that one plus several others from an equipment broker
somewhere near where he lived.
He then came across my interests in obtaining such a case and decided
to make it available. The only thing to pay was its shipping costs.
He confirmed that it was possibly designed as a trainer for that
family of processors.

The big problem is that he wasn't able to provide anything else. Which
is why from the outset neither could I.

I shall be posting those photos later in the week.

Hello Greg,

This was asked.

Please describe the brand and model of your "S-100" system. If you see
a brand and model name/number on the power supply, please describe
that. If there are multiple boards in the box, please describe the
brand and model of those boards. Is "the terminal" part of the system,
does it work independently, ????

You answer bring us no closer to knowing that.  It's helpful to know
so we can be specific as S100 was generic and also totally random
as to how it was implemented.  I can say this as I have a wide
selection of the common and not so common S100 hardware and multiple
S100 crates all working.

For example  there are multiple "flavors" of S100 power supply.  Brute
force transformer/rectifier/capacitor, those that had a Constant
voltage transformer feeding the brute force rectifier and capacitor,
and those that had some form of regualtor either linear or LVSMPS.

By identifying brand, model or even cahhis vendor it's possible to
narrow answers about the PS and backplane.

Allison

Hello!
P/S identification and the obvious board identification should be
online by the 26. I do agree with you that more information would be
useful here.

The chassis indeed one of the classic "Godbout" ones, that much I can
confirm now.

The Godbout are dirt simple using a CVT and brute force
rectifier/filter as are the more common Compupro (same outfit).
Barry did point out there are later Compupro (CSC) versions with
a more sophisticated linear supply but they are less common
and non-complient s100.

My big problem is that the information I was given was scant at best,
all he (the seller) could give me was that much, and also that the
name on its front which was "Digiac".

That is usually the starting point. LIkely though that was a thrid
party reseller.

A written description of the boards often works as to what CPU
and any board level markings. Most vendors put their names
on the board somewhere visible. That would eb a starting point.

One detail: S100 systems could be a single vendor box like
Compupro or Comemeco or they could be a laundry list of
various boards from multiple vendors. It's not uncommon
these days to see a S100 crate that was populated with
random S100 boards that was never powered up being
sold because the owner had no idea what it was other than
"Ebay Rare".

Allison

---
GCL

.

Relevant Pages

  • Re: Restoring an S100 system
    ... Please describe the brand and model of your "S-100" system. ... I do know that everything is inside a standard chassis such as ... the ones Altair and of course IMSAI used for their systems. ... "The text by Artwick"? ...
    (comp.os.cpm)
  • Re: Restoring an S100 system
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