[comp.sys.ibm.pc] Upgrade 286 to 386SX

djb@wjh12.harvard.edu (David J. Birnbaum) (09/14/89)

I am interested in information about the possibilities and
procedures for upgrading my 286 to a 386SX.  I am particularly
interested in the virtual 86 possibilities of the 386, rather
than any increase in speed.  I would also like to economize
by scavenging as much as I can from my 286 system, even if
this will limit the speed of the upgraded system.

I currently have a CompuAdd Standard 286 operating at 12 MHz
with zero wait states.  There is one meg of 80 ns ram (256k
chips) on the motherboard.  Therer is a Phoenix BIOS, version
3.07 (dated 5/27/87).  The bus operates at 8 MHz and is hosting,
among other things, a LIM 4.0 board with 4 MB of 100 ns memory
(1 MB chips).  The board can be configured to backfill system
memory or to function entirely as extended, rather than expanded,
memory, as needed.  I would like to be able to use both the
motherboard memory and the expansion card, with the understanding
that the bus speed could degrade performance speed.

I am amenable to CPU upgrades, new motherboards, or whatever
else might work.  I have seen advertisements for 16 MHz 386SX
motherboards for under $400, which seems like a reasonably
inexpensive route (or am I deceiving myself)?

I know virtually nothing about support chips that might be
required, BIOS version to seek out (or to avoid), or other
details.  Are there compatibility problems with some avail-
able products?  I'd like to be able to run up to three 
fairly large applications in Desqview.

I can install my own expansion boards, but I have never
tried replacing a mother board or a CPU.  Is this something
a normal person without an advanced degree in computer science
can do?

Please reply by email and I will summarize responses.

Thanks,

--David

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