What was a 786?
April 13, 2009 10:46 AM   Subscribe

What do you know about a product advertised in an early 90s Computer Shopper that the manufacturer called a 786?

I remember from the full page ad that it was a 486 board with 386 processor in an additional socket, but I have no idea what purpose it served. A dual processor system with a 486 and a 386 seems unworkable, and I don't see a 386 chip adding much in the way of performance even in specialized applications. Was this just a stunt board put out to trick the clueless into buying it for bragging rights and as performance enhancing as a giant plywood spoiler on a beat up Camry? Was the 386 socket even connected to anything?
posted by bunnytricks to Computers & Internet (7 answers total)
Best answer: I have this entwined with the whole Math Coprocessor saga, towards the end of it, as being a rather silly take on the whole idea and a final nail in the coffin. Could be completely wrong though.
posted by jwells at 10:54 AM on April 13, 2009

I think you're thinking of the 387 and 487 math coprocessors.
posted by zerokey at 10:55 AM on April 13, 2009

I'm pretty sure it was a CPU upgrade board, letting you run a 486 on a 386 processor-based system. It likely went in an ISA slot and sucked wind in terms of performance. Similar upgrade boards existed for 486 to Pentium systems. I'm not sure if it had an onboard video card or if it somehow interfaced over the bus with whatever video card was installed on the host system, but it wasn't a dual-CPU system by any means.
posted by Rendus at 11:04 AM on April 13, 2009

Something like this, just not so amazingly modern.
posted by Rendus at 11:10 AM on April 13, 2009

Aha! A memory was shaken loose. I remembered something made by Cyrix and just found this and this. Basically, it's a single chip 486 upgrade chip for 386 systems.
posted by zerokey at 11:12 AM on April 13, 2009

Response by poster: I finally found something on Google that might be what I'm thinking of. This is a board called the 786 which has sockets for a 486 and a 386, but doesn't seem to have the ability to use both chips simultaneously, as the ad promised. A basic schematic isn't much to go on though. I think the ad was for something more like jwells answer than a simple 386 to 486 upgrade as the system cost more than the typical 486 of the day.
posted by bunnytricks at 11:21 AM on April 13, 2009

Best answer: Some Mobo designs had a 386 processor as a floating-point "booster", like AMD's 386DX-40 or Intel's 80387; this would only be paired with a 486 or faster chip as a means of competing with Intel Pentiums with MMX, or AMD's 3DNow! rendering instructions.

Needless to say, the combination wasn't especially effective in terms of speed or output.

Incidentally, the "real" 80786s to hit the market were the first-generation AMD Athlons and Intel P4 chips, which paired to Slot A/Socket A (AMD), and Sockets 423, 478 and LGA 775 (Intel).
posted by Smart Dalek at 11:27 AM on April 13, 2009

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