How do you remap memory on a 386 ?

Carmen Hardina bt455s39 at
Sun Oct 8 09:34:40 AEST 1989

In article <[252da3cc:205.1]comp.unix.i386;1 at tronsbox.UUCP> tron1 at tronsbox.UUCP (HIM) writes:
>>	I've just bought a 386 machine with 1Mb RAM and intend to run UNIX on it. 
>>	One thing strikes me as odd -  only 640kb of memory is visible.
>*0386 (and in fact AT's) use the address space from 640-1MEG as the space
>for various ROMS for VGA , HD CONTROLLERS and the like.
>As far as I know , there is NO way to get it into useful space.
>You might as well shadow and get the speed.
>ALL the UNIX systems I have installed have this problem.

I am running an Everex 3000A under SCO XENIX 386 SVR2.  What I did to
avoid this problem was set the DIP switches on the motherboard to
remap the first 1MB of memory to 512K main/512 extended.  This way,
the whole thing is usable memory under XENIX/UNIX.  If the memory is
configured as 640/0 or 640/384, that other 384K of memory is not usable
by the operating system.  That was my experience/resolution.


P.S.  Sorry if the attribution lines are incorrect.
Carmen Hardina, Assistant System Administrator
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