*updating* 8088's

Allison ajp166 at bellatlantic.net
Mon Nov 19 20:58:57 CST 2007


>
>Subject: Re: *updating* 8088's
>   From: Fred Cisin <cisin at xenosoft.com>
>   Date: Mon, 19 Nov 2007 18:31:39 -0800 (PST)
>     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>On Tue, 20 Nov 2007, Alexis wrote:
>> 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.
>
>Depending on how you DEFINE "16 bit", the 80386SX is a 16 bit version of
>the 32 bit 80386[DX].  It therefore is "relatively" easy to retrofit it to
>replace a 80286.

The 386SX was 32bit core with 16bit databus (modified BIU).  While
it was cheaper to build systems around and smaller too the performance 
cost was high compared to the DX.

>The 80486SX and 80486DX are the same bit sizes.  Their differences involve
>whether or not the math FPU is included.
>
>I ran an 80386 board in a 5150 (8088) machine.  There didn't seem to be
>much point to it.
>

I ran a Leading Edge model D (PC XT clone) with an Intel Inboard-386.
It gave me 2MB ram and a 16mhz CPU (beats 4.77!) and a bottleneck of
the 8bit ISA.  However it ran winders3.1 and was a whole lot faster 
than the 4.77mhz V20.  At the time it was far cheaper than a real 386
and much better than the 8088.

Allison



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