*updating* 8088's

Alexis thrashbarg at kaput.homeunix.org
Mon Nov 19 20:21:43 CST 2007

> From: Chris M <chrism3667 at yahoo.com>
> Reply-To: "General Discussion: On-Topic and Off-Topic
> Posts"<cctalk at classiccmp.org>
> Date: Mon, 19 Nov 2007 17:24:13 -0800 (PST)
> To: talk <cctalk at classiccmp.org>
> Subject: *updating* 8088's
> We've all seen different varieties of 8088 to 80286
> upgrades. A few at least plug into the 8088's socket.
> I saw a '286 to '486 upgrade (must have been similar
> in that respect) at a show a while back (didn't buy
> it). We also know about OverDrive products. What would
> happen if you pig-piled all these things in an old
> 8088 machines? What would happen? Cataclysmic
> explosion?
> Were there ever 8086 to 80286 upgrades for the few
> machines that used them?

I'd like to see an 80286 to 80486 upgrade card. It would need to somehow
multiplex the 32-bit bus onto the 16-bit bus, perhaps running the
multiplexing process at double the CPU clock speed. The SX wasn't 16-bit was
it? Or am I thinking of the 386SX. If it's 16-bit it wouldn't need

Perhaps to hack an 80386 onto an 8088 board you could take a 386SX and run
it at 1/2 of the crystal speed. I think that's 14.3MHz which would be about
7.2MHz, where each of the crystal clock cycles latches a consecutive byte of
data and the 1/2 speed is sent to the 386SX. A 74F646 would be good for the

You might run into an issue of minimum clock speed too. I don't know what
the minimum for the 386/486 is. I know RISC microcontrollers can go down to
DC, but the 8386/486 might not.


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