Some Processor Tech history

Amardeep S Chana:I finally got around to cleaning the heads and setting the jumpers on a dual 8" drive unit so it could be hooked up to my Z-2. The drives are Qume 842 DSDD units. As it turns out, much to my dismay, the [Cromemco] 16FDC 8" disk connector is wired for Persci disk drives and will not work properly with standard Shugart type drives without some board mods.

Barry Watzman: Later this summer, I will have at least one, possibly two, Processor Technology "SOL-20" and "Helios" combinations (I'm currently rebuilding a stash of Processor Technology equipment that I recently purchased). The SOLs will be (already are) tested and working, I'm not yet sure of the condition of the Helios' (Helii ??). The Helios box was just a very sexy Persci drive case & power supply. Since the Persci drive was indifferent to hard vs. soft sector, the Helios drive box can run CP/M as well as PTDOS if you use a different controller (the PT controller used for PTDOS was hard-sectored). Any controller that supported the Persci drive can be used, which is just about any Western Digital based controller at all (Tarbell, Cromemco, etc.).

Randy McLaughlin: Actually the jumpers for the Persci's included in the Helios were hugely different than the Persci's shipped by Cromemco. As memory serves the Helios version worked fine in a Cromemco but to use a "Cromemco" Persci in a Helios you had to re-jumper it. I no longer own a Persci but.. could you post the jumper settings for the Helios and maybe someone that has one of Cromemco's oak Persci's can do the same with theirs. Also as I remember Persci shipped the drives jumpered as in the Cromemco version when you bought direct. I still have my original Persci manual and a PDF of it is available on my Web site.

I only dealt with a couple of Helios systems. PT shipped the boot loader on cassette and I was never able to get the first one to boot (no help from PT either). I ended up putting a 4FDC on the first one. I had to translate RDOS to 8080 code and make my own CBIOS to support CP/M since getting CDOS to run on an 8080 was too big a job. Much later PT came out with different SOLOS ROMs to boot directly.

Thomas "Todd" Fischer: The Helios was single-density, hard sectored, and was available with either one or two Persci 270 drives. I don't believe that Lee Felsenstein ever specified or re-designed for the dual-density 277, or "quad-density" 299.

I, at an earlier time, had probably worked on more Persci's than anyone else, having them shipped to us at Fischer-Freitas in Oakland, CA from as far away as Australia. The Persci 270 was the single density, dual drive (in a single full-height form factor); the 277 was double density, and the 299 was dual drive, dual density.

It required a Persci 499 disk exercisor to align and test the drives. Scale lamps, rabbit hair head pads, voice coils, and glass positioning scales were the most common replacement parts. Persci was sold to another group in late 1980, with the result that parts became VERY expensive.

My wife Nancy and I bought out a portion of the Processor Technology inventory when they went bankrupt in 1981, primarily for the Helios/Persci inventory. The Persci had about 27 documented jumper configurations for various OEM applications. I disposed of my exerciser and documentation in 1989, so don't have any of my original notes and documentation. I still have two of the 277's available for anyone who has a keen interest. Both were working when last used, and they are jumpered for soft-sector, double density operation with the IMSAI disk controllers. This should be the same as Morrow Disk Jockey, CompuPro, and other similar controllers that used the Shugart 851-style interface.

I always related the Persci as a kind of exotic European sports car; incredibly fast for the short term, but prone to regular service and adjustment. An innovative, but unreliable and complicated design.

Randy McLaughlin:My experience is tiny compared to [Fischer's] but my experience says they are fast, I loved mine when I had one.

It was from memory that I stated that the 277 was rated for FM. After reading your post I opened my 16FDC manual (available on Howards site) and Cromemco recomended not using the 277 for MFM (page 61 of the 16FDC manual "Note that the PerSci Model 277 is not specified for for double density operation"). My Persci manual doesn't say anything about density at all. My experience with the 277 agrees with you in that I never had any problems with MFM.

I only dealt with two Helios systems, both came with 277's but the Helios controllers were FM. On one I ended up setting up the drive to work with a 4FDC. Both systems were a pain to get running. The PerSci drives worked fine........

When Cromemco came out with the 16FDC's I got one very early and was heart broken when they said I should now turn around and buy and expensive 299. I never bought a 299 for myself I used my 277 from the beginning with no problems (luckily). I talked to Cromemco and they reiterated that I shouldn't use a 277 with the 16FDC, I ignored their advice.

Lee Felsenstein found my Processor Tech notes on this Web page, and wrote to me in August 2005. Quoting with permission:

> Herb,
>
> My periodic Google search on my name turned up the
> Retrotechnology page on "Persci Floppy Drives and
> Processor Tech" in which my name is mentioned a few
> times. I'd like to make a few clarifications.
>
> I was never a founder or a principal of Proc Tech (as
> we called it - sometimes I would call it "Proctology"
> when I answered the phone for them). Bob Marsh talked
> me into going in with him on the rental of a garage in
> industrial Berkeley in late 1974 so we could both set
> up our fledgling electronics firms. Mine was a
> sole-proprietorship doing contract electronic designs,
> mostly for former supervisors and co-workers laid off
> from Ampex Corporation (where I had worked 1968-1971).
>
> Bob was looking for a product to manufacture -
> especially one which could make use of center-cut
> walnut pieces he could get from a friend who had moved
> to Wisconsin and was in the wood business. He
> considered a digital clock but his attention was soon
> drawn to the Altair in January of 1975. He convinced
> me to drive him to the first meeting of the Homebrew
> Computer Club in March. Soon Processor Technology
> Corporation was born, but I was an outsider who
> contracted to them to do design and documentation
> jobs.
> My major works for them were the VDM-1 and the Sol-20.
> Unfortunately, I was not allowed to do the PC board
> layout for the VDM-1, and it went to a totally
> inexperienced guy as his first job. It shows. I would
> hate to have to defend that piece of work, which was
> laid out without a pencil preliminary layout and has a
> ribbon cable conducting the data bus across the board
> as an admission of failure. I could have done it much
> better.
>
> And of course, my contract included a royalty, which
> was the best money I ever made. Not the most, but the
> least encumbered.
>
> Still, at one point in 1976 I was asked, entreated,
> nay required to come in and serve as acting interim
> engineering manager. Management thought that there
> were only a few tasks remaining to be done. I
> interviewed all the engineers and came back with a
> list of at least twenty major tasks. When Gary Ingram,
> the President and co-founder heard this he cringed and
> waved me away, shouting OK! OK!.
> It was at that time that the Helios design was being
> completed for manufacture. I deny any responsibility
> for that, the memory boards, or nearly anything. When
> I got free of that entanglement and the company moved
> to Pleasanton (Gary's home base) I would journey
> weeklyi down there from Berkeley to talk with them
> about new designs. Eventually I took on other
> contracts and when finally I asked them "what the hell
> do you guys want?" they replied, "we don't know, we
> were waiting to see what you came up with." During
> that time (several months in 1978) I could have done a
> lot - like a Z-80 Sol capable of CP/M, for example.
> Bob Marsh has told me that one of many stupid things
> Proc Tech did was to get adversarial with North Star
> and get into a lawsuit with them (over a disputed
> version of BASIC). He says now it's clear that they
> should have cooperated in integrating the North Star
> disc system into a new version of the Sol. Sigh.
>
> Proc Tech closed its doors in 1979, just before the
> National Computer Conference in New York. I know
> because I was there with my VDM-2 almost-working
> prototype looking for their booth, which never
> appeared. I have also heard stories recently that
> indicate that they closed down not out of necessity,
> but out of choice. I will not repeat those stories
> because they reflect well on nobody. It's over.
>
> Using the Persci disc drive was one of many small
> disasters that compounded to bring them to that point.
> I can't take responsibility for the design
> misdecisions - I had nothing to do with them. It was a
> clear case of amateur management and growth beyond the
> level which will tolerate such management.
>
> Of course, it's always tempting to wonder how I might
> have integrated the North Star controller onto the
> main Sol board and maybe included some of the VDM-2
> features (smooth scrolling, writeable font) in the
> design as well, using chips that were available at the
> time. That would have been a killer!
>
> Lee

When I asked his permission, he replied:

"Herb, Permission to reprint is granted.

"Also, you might want to note that Proc Tech's first product was a 2K EPROM board, but this is nit-picking. The 4KRA RAM board was the first significant product - one that made the Altair a workable machine for the first time. When [founder Bob Marsh] peeked into MITS' Altairs at the World Altair Convention in Albuquerque Bob Marsh said that he saw many 4KRAs in the boxes.

"I don't have a website but am getting one together. I can link [you to] it when it's ready, but the focus will not be on computer history.

Thanks for doing this. History has much to teach us. - Lee"