cctalk Digest, Vol 31, Issue 7

Allison wrote; Rick Bensene wrote: I never saw one of those, but the computer center I worked at in college dumped a Cincinnati Milachron small business computer system - *not* a machine tool controller. I tried to grab it, but that was not to be. Same thing - there's no record anywhere I could find that they were ever in that business. <...> I actually ended up with a complete SCM 7816 system, including: - The I/O Printer, which was a hacked SCM electric typewriter, with diode-matrix encoding for the keyboard, and relay decoding for the printer; it used a row of washers to mechanically ensure that only one key could be pressed at once. It also had a paper tape reader built into the back of the carriage, so that some computation could be triggered by the carriage position, or performed while the carriage was returning. - The main 2816 control unit, with a plug-board "output panel" to route data between the various peripherals; this also had the massive power supply, which used a ferro-resonant transformer to regulate all of the voltages. - The optional (!) 7816 arithmetic processor, which did bit-serial addition, subtraction, or multiplication (no division, but this was simulated by using reciprocal multiplication); there were nine 10-digit registers (no other working memory), all implemented on a fixed-head disk, plus a buffer implemented electronically. Add time was 17ms, multiplication 700ms; this is why the ability to do calculations during the carriage return was valuable. - Two paper tape punches - these were re-branded CDC punches, and were very nice units. 40 characters per second, with a built-in automatic verification; they could also be used to punch on the side of cards, instead of tape. - Two paper tape readers. These were built by SCM, and were pretty nice too; they were optical, would read at 30 characters per second, and could stop from full speed on the next character. - The custom desks, which included a recess for the I/O Printer to sit in, and acted as chasses for the 2816 and 7816. - All of the manuals and schematics for the whole thing. Some of the logic was made using thick-film modules, but most was on the vintage single-sided boards, with obviously hand-drawn traces and jumpers on the component side. Somebody has uploaded some of the manuals and 2816 schematics to bitsavers, but not the schematics for the 7816. With the complete schematics, I was eventually able to get the thing to type and read and punch tape, but I never got the arithmetic unit working. That machine was *really* dumb... I carted the whole thing around for about 15 years, until the new wife decided that she was more important than the space it consumed. That's OK, I guess - I eventually ended up dumping her, too... ~~ Mark Moulding