1970s Data General Mini Computers - Page 1
Forum section: electronics / general

author: AE7OO
author_rank: Regular Contributor
timestamp: January 27, 2020, 11:42:52 am
content: I don't know if anyone even uses them anymore, but the 80S and 90S Supermarket scanning systems from Sweda are the Nova and Eclipse. So if your looking for more, or parts to repair, that might be another source.I spent way too much of the early 90's working on the things.Core memoryDisk packsetcGB AE7OO

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: April 24, 2020, 04:43:31 am
content: Now I know what happened to those two machines! I wanted them soooooo badly, but I am totally out of space. There's just no way to jam them in.I really want an Eclipse system with a 9-track tape drive though. I worked with one in the 80's, but never got to tinker or program on it because it ran the business. I have lost tinkering time to catch up with!

author: rdl
author_rank: Super Contributor
timestamp: April 24, 2020, 05:59:31 am
content: Development of the 32 bit Eclipse was the basis of "The Soul of a New Machine" by Tracy Kidder, a most excellent book that anyone with an interest in computers should read.https://en.wikipedia.org/wiki/The_Soul_of_a_New_Machine

author: Gixy
author_rank: Regular Contributor
timestamp: April 24, 2020, 06:33:39 am
content: +1

author: jfiresto
author_rank: Frequent Contributor
timestamp: April 24, 2020, 09:08:55 am
content: The youtuber's microNOVA was built around the 1970–1980 transition. The summer of 1981, I wrote the purchase order for an MP/100 system which came with restyled front paneling. I preferred DEC equipment because it was generally better engineered and documented. Fortunately, the service engineers at the local Data General office were very helpful and kept us up to date on Field Change Orders and such.My second personal computer was a DEC 11/23+ in twin, half-height equipment racks. I had to get rid of it as it was just too much to move. A friend kept the 9-track tape drives and formatters as he couldn't bear to see them go.

author: radiogeek381
author_rank: Regular Contributor
timestamp: April 24, 2020, 03:54:58 pm
content: "The Soul of a New Machine" is a great book. It captured the design environment and what it was like to design minicomputers in MSI and SSI before simulators made much of the "cut and try" method obsolete.But the book was about the 32 bit Eagle -- intended to answer Digital's VAX product line. The Eclipse was 16 bits wide and competed with later PDP-11 models.

author: coppice
author_rank: Super Contributor
timestamp: April 24, 2020, 04:04:45 pm
content: Quote from: radiogeek381 on April 24, 2020, 03:54:58 pmA lot of people like that book, yet it documents a misguided project that lead to a failing product.Developing computers from MSI chips wasn't cut and try. The parts were specified well enough that if you followed the specs properly, anything that didn't work right first time was your own fault.

author: radiogeek381
author_rank: Regular Contributor
timestamp: April 24, 2020, 08:46:41 pm
content: QuoteI think you are substantially right. However, the problem was rarely the parts. By the early 80's simulators had come a long way, but still in most places (and at DG and Digital in particular) they weren't up to doing things like boot an OS. For the most part, we ran "diagnostics" -- note that even these weren't the validation tests we use today.The problem wasn't the parts -- it was the complexity of the machines and the software that ran on them. In the absence of simulators (and timing validation tools) efforts at DG and Digital relied extensively on prototype debug. Interactions between cache-misses, interrupts, page faults, and traps are *really* hard to get to if you can only simulate a few hundred thousand instructions per day. I worked on bugs that took hours -- sometimes *days* -- of runtime on a *real* system to surface.On top of that, timing verification at the time was somewhat primitive. The tools that existed were often based on simulation (requiring timing patterns) which was almost always inadequate. Static timing analysis was yet to come to most of the minicomputer companies. Most timing validation back then was done at a desk with pencil, paper, schematics, and spec sheets. Even with relatively modest and synchronous designs, this was hard. There were tools that would help, often eliminating much of the drudgery and hand work, but they were not as exhaustive as we have now.So, the typical process was -- specification, design and microcoding, limited simulation, proto or brassboard builds, followed by massive amounts of "design validation test." The DVT stage could tie up many prototypes or systems from a "pilot" line, lots of real-estate, and thousands of hours of work by OS, compiler, application, and diagnostic developers. The DVT phase could last months. Then systems were sent out to a select set of customers for beta-test. Only after that, and lots of bug rework, was the system design released to manufacturing. Even at that, given the rather complex instruction sets (good idea at the time, you had to have been there...) there were microcode updates for years after the product entered volume production.So you are right -- MSI circuits were pretty reliable. (With a few exceptions -- Fairchild's FAST series had some hidden timing surprises that caused troubles for MULTIFLOW and Digital -- perhaps others. In one case it involved a massive ECO that had to be performed on a very large (for us anyway) installed base.) But still, construction was "cut and try" or "iterative design" as unintended interactions were discovered and oversights realized.Perhaps you were more fortunate in having access to better CAD tools. Or perhaps the systems were not as complex. But developing a "super mini" was anything but a "follow the rules and you'll be fine" kind of operation.(I got to Digital in the early 80's and worked on a few VAX generations, and the Alpha product line until it was bought by Intel. Engineering complex machines is *much* different today.)

author: rdl
author_rank: Super Contributor
timestamp: April 24, 2020, 08:59:17 pm
content: The new machine was referred to as the "Eagle Project", but was eventually sold as part of the "Eclipse" line.https://en.wikipedia.org/wiki/Data_General_Eclipse_MV/8000I made it a point to check that before my previous post because it has been 20 years since I last read the book. Of course, wikipedia could be wrong.