20 Nov
2007
20 Nov
'07
2:21 a.m.
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
multiplexing.
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
latch.
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.
Alexis.