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286 accelerator boards & compatibility with 8086 systems

raifield

Experienced Member
Joined
Aug 3, 2010
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174
Location
NJ, USA
A lot of the 286 accelerators I see on eBay are advertised either in the auction itself or old issues of Infoworld as being replacements for the 8088. Does this mean that they wouldn't be compatible with the 8086 for some reason? To confuse me more, I remember reading an old Infoworld magazine on Google Books that reviewed several accelerators and two of the boards had an 8086 CPU and one even had a NEC v20, which seems odd...why wouldn't you just lift the 8088 out and pop the NEC in?

Anyway, there are a few boards on eBay and I was wondering if I'd run into issues with using one in an 8086 IBM Model 25 just for kicks, but I haven't been able to find decent information elsewhere.
 
I don't know about the other accelerators available, but both the Sota 286i and 386i will upgrade an 8088 or 8086 processor. You just set jumpers on the cards.
 
That's where the confusion lies. I'm assuming you'd set the jumper to instruct the card to send either 8 bits or 16 bits down the ribbon cable at a time, but then it seems that a 286 accelerator designed for the 8088 would work in a 8086 system, just at 8 bits similar to how some of the earlier Tandy 286 systems operated. That would still be an improvement over my v30/8087 combination, but maybe not at the price the cards are going for.
 
What card specifically? I have manuals for both the Sota 286i and 386i at my website and I want to say that the Microsoft Mach20 and Orchid Tiny Turbo manuals are online...
 
No specific card, was looking to find out what the deal with most accelerators claiming support for the 8088 CPU and neglecting to mention the 8086. I saw a Microsoft Mach 20 on eBay awhile ago that I was thinking of getting, but again, all the material I could find on the card (advertisements, couldn't find manual) only mentioned the 8088, so I got curious about the lack of stated 8086 support.
 
The Orchid PCTurbo 186e/286e (not to be confused with the Orchid TinyTurbo) will at least work in a 8086 since these cards don't use any ribbon cable at all. As for the others, it's problably as others have mentioned; it depends on the card and eventual jumper settings.
 
8086 and V20 upgrade cards would have made sense as clock doublers, especially if they added some kind of cache memory too. I'm guessing those were probably targeted at 4.77MHz IBM systems since most clones probably already ran at 8 or 10MHz.
 
I wish there had been tech note collections on cd-rom. I have a few pieces of software (like MS Windows) that include notes on running with accelerator boards. I suspect that the manufacturer of the card had knowledge of numerous minor incompatibilities with software and other expansion cards. But it is all lost and now one gets to rediscover all those issues.
 
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