Solid State Music S-100 Iain McFetridge Notes

Please check my S-100 Solid State Music document list page. For my S-100 home Web page follow this link. This page Last update Mar 15 2024. This document copyright Herbert R. Johnson 2024, documents from others have their copyrights.
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On this Web page are notes from Iain McFetridge who designed the SSM VB3.- Herb

Conversations with an SSM designer

[SSM VB3A card]

In late September 2003 I was contacted by Iain McFetridge, who designed the prototype Solid State Music video card model VB3. He was surprised by all the current interest in S-100 equipment. When he found my site, he started a conversation with me. I've slightly edited that dialog and with his permission here it is. I've added footnotes in italics, and some comments in square brackets. -- Herb Johnson

Date: Fri, 26 Sep 2003 18:04:09 -0700
From: Iain McFetridge

OMYGOD..U have info on the VB3 video card??

WOW..I havent seen one of those since I built the prototype

I am Iain McFetridge the designer of that card.. My partner Ben Gee (software guru) and I did that board while we worked for Four Phase Systems. We sold the design to SSM for X amount of dollars plus X amount of money for each blank PC card they made. Didn't make a whole lot from it, but it was fun doing. I designed that vid card with an SMC video controller chip because my IMSAI's glass teletype [CRT terminal] didn't have any graphics I made the VB3. I later changed it so you could put three or more video cards into it so it would function with an RGB colour monitor...

Wow, what memories! Eight ram cards with 32 1K RAM chips* to get 64 K of RAM. Tarbell floppy controller [card] running two 8" single sided floppy drives (what a clatter when one copied a disk!) Three VB3 cards; an SIO; and a Z80. Hot dam - now THAT was a computer! I can almost remember the boot sequence [to load the operating system] into RAM. Oh, I almost forgot the ROM board with Tiny BASIC (that I blew into a ROM burner one byte at a time [based on] a BYTE magazine article.

[VB3A initials] I would LOVE to see a picture of [the VB3] just for old times sake. Does it have my and Ben's initials by PIN 100 (right hand side of edge connector front, I believe)?? They would be IM/BG or something like that. It's been a long time, and sometimes my memory fades a little. Well, thanks for the short trip to my past. I stumbled on your web page while looking for S100 stuff..Don't mean to intrude...

Iain McFetridge

*Actually it's 64 RAM chips per card. Eight chips per 1K byte of RAM, with eight sets of eight chips for 8Kbytes of memory per card.

From: Herbert R Johnson
Date: Sat, 27 Sep 2003 09:42:26 +0100

It's not an intrusion when a S-100 designer contacts me. I appreciate your history of the VB3 card. May I put your remarks on my Web site? I'll not include your email address to protect your privacy. YOu are welcome to add a bit more info, such as dates and years, and I'd like to clean up some of the typos. Of course you wrote it as you were thinking so don't be concerned, in fact your writing shows a lot of the enthusiasm that people have for S-100 technology.

Also if you have any information on SSM the company, I'd be interested in that as well, and in putting that info on my Web site or including it for publication in a S-100 book. I wrote several articles in the 1990's about S-100 repair and technology, which in due course I'll publish. Notes about major S-100 companies would be a good addition to that book. In any event I plan to post more info on my site about each S-100 company. With your comments I could expand my SSM page with photos of a card or two.

I'll look in my inventory but I probably have a VB3card on hand and I can check for your initials and such, maybe post a photo on my site. If you still have some of your notes and design drawings for the VB3 I'd be interested in copies or originals. Part of my work in the S-100 world is to preserve information as well as to distribute it to help others maintain their S-100 systems. Let me know any terms you might have regarding use of whatever you might provide.

Most particularly, I'd be interested in those "upgrades" that allowed three cards in tandem for RGB. That would be a nice document to provide to owners of that card!

It's a pleasure to hear from you, and I hope you'll have more to say. Thanks again for contacting me.

Herb Johnson

Date: Sun, 28 Sep 2003 02:47:50 -0700
From: Iain

It tickles me to no end that you wish to put my old crusty thoughts from YEARS ago on a web site. Is there that much interest in how it all began??

Hmm..dates and such are a problem. I don't have any docs or schematics or even the old prototype of the VB3. It's funny though: I sit here trying to remember what it was and all I can get is fuzzy memories but other memories come in so sharp and clear. Like when I first got my IMSAI its mainboard had only 6 slots (I think), not nearly enough for what I wanted to do. (Big dreams of a computer that would beat ALL computers..LOL [laugh out loud]). So the first thing I did was find a substitute Motherboard that filled the whole IMSAI chassis. As I said before, I worked at the time for a company called FourPhase systems. It was located in the south bay in Cupertino [CA] as an R&D tech. My teachers were engineers with BA's and PhD's, the best in the world. It also meant that I had MANY parts manufacture's reps [i.e. salesmen] always coming and going.

I did a lot of parts testing for the company and when I helped pick one company over another for main source they would not blink an eye if I asked them to supply me with twenty 100 pin edge connectors for a "project" I was working on. So I had that IMSAI filled to the brim with slots. What I didn't do was load the IMSAI's power supply correctly. The first time I powered it up with only the CPU board and the front panel to load that MASSIVE powersupply. Needless to say the CPU board (Z-80 based) decided to turn all the [voltage] regulators onboard to carbon (we used to call it essence of Alan Bradley*) for the smell was terrible.

That's when I decided to load the power supply the most logical way: with boards..lotsa boards. This was when I discovered a neat little company called Solid State Music or SSM, which made of all things kits for S100-type machines. But the neat thing was they also sold just blank boards with parts lists and schematics.

*Alan Bradley was a resistor manufacturer. Resistors were made of carbon. And to be precise the voltage regulators would cook but they remained mostly silicon and plastic.

This was wonderful for me for I had all sorts of access to parts new and used. So each paycheck went into buying their biggest memory board (blank) that they had. It was an 8k board (8x32 memory chips that used 1kbit static RAMS). So I would get old socked boards from the manufacturing plant that were being scrapped, and carefully pull the sockets out of them for my memory boards. This took many weeks of collecting, desoldering,.resoldering etc. Soon though I had 8 memory boards but without a single chip of RAM. But that was not a real problem, I just called my tech friends over at one of the memory manufacturers, and he brought me a box of 1K ram chips that they "tested" to see what they needed to do to them to make them fail. The ones he gave me all passed every thing they could throw at them without failing. Oh, and that "box"? It was one foot by one foot by one foot FILLED to the top with RAMchips..

So one night I gleefully filled all 8 of my ram boards with the best RAM available (they were ceramic military spec RAMs).*

*In the late 1970's, 2102 RAM chips probably cost a few dollars US each. Military specification chips were made with a ceramic case, not plastic, and worked at hotter temperatures; they were even more expensive. To fill 8 cards he used 512 chips: plastics at $3 each would have been $1500 US, and his chips were worth even more. Lucky guy...

I built other boards for my machine..a Tarbell Floppy controller..A Serial/Parallel board for my Teletype (yeah the thing went chugchugchug caching). An EPROM burner that I burned Tiny BASIC into from a Byte Magazine article into a one K EPROM one byte at a time from the front panel of my IMSI..took a whole weekend..

Sheesh..the more I remember, the more astonished I am about how bloody obsessed I was with electronics. I mean besides making the Teletype machine print out tonnes of letters one at a time..or make the blinky lights on the [IMSAI] front panel blink in predictable patterns. My "computer to beat all computers" with massive amounts of memory didn't even have an operating system. Heck, I couldn't even SAVE any of my programs I wrote in Tiny BASIC. So I kept adding cards....

After the memory came the tape player board (can't remember if it was Tarbell too). It would take a Radio Shack mono cassette player and that would be the storage device for my programs. So now I could write a tiny basic program to type the alphabet on the teletype till it ran out of paper, and SAVE the program to a tape till I got another roll of Teletype paper. What fun...

Next came the games: Lunar Lander..Startrek (my favorite) etc. Pretty simple now adays but back then you didn't just go down to the game store and buy a game. They were found in the pages of magazines like BYTE Magazine and one would have to input them into tiny basic one line at a time. Then [you had to] debug the code to get the typos out; or to change the syntax for different versions of Basic. I think it took me two weeks to get startrek to work and that's 4 to 5 hours a night EVERY night.

Then at work someone found me an empty terminal case with just the picture tube [CRT] and electronics to run the tube. It had separate video, horizontal and vertical signal inputs. It was my first step in building the VB3 video card. I bugged a couple of the engineers as to how to go about making it a dumb terminal. One of the engineers who worked in the terminal design section for Four Phase Systems pointed me in the direction of a couple of video chips that were just coming out on the market. These were chips that were the forerunnersof the modern GPU [graphic processing unit] chips that we use today. They would with [the right] programming put out vertical, video and horizontal signals; with an interface to RAM for video buffering, and to ROMs that would have the character set in them for the display. I added some circuitry for keyboard and serial interface for my IMSAI and had in the end a bulky but wonderful dumb terminal that would emulate an ADM or a Televideo terminal.

Now why would I build something that someone else already made?? Well if memory serves me right, an ADM3 [video terminal] cost about $1000 US back then and didn't do nearly what mine could do. So now I had a terminal that didn't go chuchugchug caching and it used NO paper. But it was as BIG as my IMSAI! With a monochrome (green) screen and it only did characters with a very limited graphic set. I didn't like it..

I'm gonna stop here so I can get some sleep. I will continue the story in another letter. Save it and I'll try to piece it all together with dates as I go. After all, this IS 25 years back or more that I did all this.

Date: Sun, 28 Sep 2003 10:30:41 -0400 (EDT)
From: Herb Johnson

Actually, your description of computer life in the 1970's is pretty realistic. I was there myself, as a electrical engineering student in the 70's and a designer and programmer for little and big companies in the 1980's. I think I"ll be able to use all of your discussion on my new site, which will be more about history and use. But I can put some of the SSM stuff right on my SSM page, I need to add some flavor to it as right now it's just a list of docs.

Do you really have nothing left from that era? No notes, docs, correspondence, hardware? One reason people are interested today in that hardware was that they either could not afford it then or they did not keep it around, and now they have a bit more time and money to play with it again.

I read through your remarks, which include how you came to build the video card that became the VB3, so thanks for that info. I suppose the next step is how SSM found out about it and how you worked with them to get their VB3 running and in production. Or did their engineers simply "run" with your design? You might also say what your friends and other engineers thought about all this. I've enjoyed your remarks and I'm sure other people of the era will also. But more to the point, younger people today who have no inkling of how it was back in the 70's will get an idea of how it was then.

I recently recieved some Heathkit material from a widow. She said she wanted them distributed and available "to show there was a time when people BUILT things with their own hands". Your story goes right to that point, and I appreciate your descriptions.

You asked me about images and docs of your card. I checked my hardware inventory. Here are the SSM video cards I came across, with PC board copyright dates and signifigant chips:

VB-1, (c)1976, uses Motorola MCM6571
VB1B,    1977, same layout as VB-1
VB2      1978, Signetics 2513N ROM, two 8212's
VB3A     1981, SMC CRT8002, SSS (40-pin chip), 2716 ROM

The VB3A has your initials as you noted. I've photographed the VB3A and I'll put it up on my site in a few days. Also I've photographed a typical 8K memory card (64 2102 chips) since you mentioned such cards in your remarks.

Regarding SSM video board docs, I have:

     VB1-B Video Interface 42 pgs
     VB2 Video Board, 1978, 42 pgs
     VB3 80 character Video Interface, 1980, 72 pgs + 68 pgs source
     VB3A 80 character video interface,
          VB3A Instruction and reference manual, 1981, 60 pgs + 38 pgs source
          VB3A Assembly and troubleshooting manual, 1981, 12 pgs
          SSM VB3 6 X 7 character EPROM retrofit - ROM dump, 6 pgs

I can send you the VB3 docs at no charge as a courtesy for providing your remarks. Let me know which VB3 sets you want. I'm sorry to hear you don't have docs from that era, I'm always looking for more S-100 documentation.

Herb Johnson
New Jersey, USA

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