16-Bit CPUs on the S-100 bus

General discussions related to the Altair 8800 Clone

Re: 16-Bit CPUs on the S-100 bus

Postby Wayne Parham » October 14th, 2022, 6:40 pm

MajorClements wrote:You mentioned IBM shops, were they authorized dealers to sell IBM systems or did IBM have physical brick and mortar stores for clients to checkout the latest and greatest?

When I said "IBM shops," what I meant was IBM customers. Companies that used IBM computers were "IBM shops" by my vernacular. Lots of people talked that way, like saying "Walmart is an IBM shop" or "Cities Service is a Data General shop."

Some large companies had computers from various manufacturers, but even then, they often had more systems from one particular manufacturer or another. Once you have staff start becoming familiar with an architecture, they tend to coalesce as they bring in new-hires. The talent pool at the company becomes familiar with one platform or another, and specialization is a natural side effect. Sales staff builds relationships with people in the company, and that keeps 'em in "in the fold" too. So you saw "DEC shops" and "Data General shops" and "IBM shops."

As for sales avenues, you really didn't see retail outlets form until microcomputers hit the scene. Minicomputers were generally sold directly from the manufacturer, largely using outside sales staff. They visited customers often, sometimes even having people onsite at a customer location full time.

Another common sales vehicle was OEMs - Original Equipment Manufacturers - which bundled systems and software, often with their own specialized hardware and software - to support a specific market segment. An example is Ross Perot's EDS Electronic Data Systems.
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Re: 16-Bit CPUs on the S-100 bus

Postby ribarrjr » January 17th, 2023, 10:16 pm

Wayne Parham wrote: It was actually patterned after the Data General Nova 2, but the 16-bit Eclipse's had a very similar front-panel.


I happen to have on of these front panels in the my garage. If anyone has a Bus pinout or any other information of them It would be nice to see if I can get the lights to blink.
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Re: 16-Bit CPUs on the S-100 bus

Postby Wayne Parham » January 18th, 2023, 5:00 pm

That's awesome!

I'll look and see if I can find schematics. I know I have schematics for a bunch of DG peripherals in the form of paper manuals. What I don't know is if I still have some of their documentation on microfiche. I used to have schematics of everything from Data General made prior to 1980. I think I still have those fiche bins in storage. If so, I'll report back here.

One thing though - Data General front-panels used incandescent bulbs. If you were wanting to restore an old Nova and make it period-accurate, obviously you'd want to keep 'em. But if you aren't trying to do a period-correct restoration, I'd suggest using white LEDs. Either way, if you want to do a full restoration, you might want to check out Wild Hare Computers, who has done third-party support for DG systems and peripherals for decades, and amazingly, still does.

Do you have the Nova chassis with backpanel, CPU and memory? Or do you just have the front-panel?
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Re: 16-Bit CPUs on the S-100 bus

Postby ribarrjr » January 19th, 2023, 1:36 am

That would be amazing! I have spent many hours searching for any technical documentation on the 16 bit Data generals without much luck.

I have already pulled the front part of the panel off to clean off some sawdust (It had been sitting an a garage for a few decades) and much to my dismay a few of the light bulbs fell out. The bulbs as they are soldered straight to the board so I think I will end up replacing them with some "incandescent" colored LEDs so I don't have to ever worry about changing them again.

It's an Eclipse panel. I only have the front panel and some rack-type cases which were used at the same location thought I wasn't able to verify if they are the same cases that held the original computer.
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Re: 16-Bit CPUs on the S-100 bus

Postby Wayne Parham » January 19th, 2023, 12:26 pm

Here you go:

That shows the circuit Data General used for its front-panels. Other models used that same basic circuit too.

Incandescent lamps don't need current-limiting resistors, but LEDs do. So you'll need to add them when you swap-in LEDs. Be sure to include a series current-limiting resistor for each LED. The typical 220Ω or 330Ω value will be just fine. Choose the resistor based on the intensity you want. You can certainly go larger if the LEDs seem too bright for your taste.

The 1KΩ resistors you see in the schematic weren't for current-limiting, and you'll need to remove them when retrofitting lamps with LEDs. They kept the filaments partially energized even when off, although not enough to glow. Remove them when swapping in LEDs, or the lights will be illuminated all the time. And of course, be mindful of polarity when installing your LEDs.

By the way, since you have a DG front-panel, you might build an Arduino or Raspberry Pi based emulator or clone. That way you'd be able to build a running Data General clone that sported a genuine DG front-panel. How cool is that?!!
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Re: 16-Bit CPUs on the S-100 bus

Postby ribarrjr » January 26th, 2023, 11:41 pm

Thanks so much! I have a few projects I'm working on at the moment but when ever I get around to repurposing the panel I'll be sure to show it off here!
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