[comp.sys.ibm.pc] Expanding Intel 386 board to 640K for DOS

davek@hp-lsd.HP.COM (Dave Kumpf) (09/07/87)

The latest issue of PC Magazine contains test reports on several '386 machines.
They tested several which are based on the Intel motherboard, including Corvus,
Kaypro, and others.  

Here's my question -- the text implied that it is extraordinarily difficult
(or impossible) to use more than 512K for DOS using the Intel motherboard,
even if you have the Intel memory expansion cards.  What's the scoop? Anyone
out there have any experiences with expanding DOS to 640K on the Intel
board?

Dave Kumpf -- hp-lsd!davek

farber@udel.EDU (Dave Farber) (09/11/87)

In article <8020007@hp-lsd.HP.COM> davek@hp-lsd.HP.COM (Dave Kumpf) writes:
>The latest issue of PC Magazine contains test reports on several '386 machines.
>They tested several which are based on the Intel motherboard, including Corvus,
>Kaypro, and others.  
>
>Here's my question -- the text implied that it is extraordinarily difficult
>(or impossible) to use more than 512K for DOS using the Intel motherboard,
>even if you have the Intel memory expansion cards.  What's the scoop? Anyone
>out there have any experiences with expanding DOS to 640K on the Intel
>board?
>
>Dave Kumpf -- hp-lsd!davek



The problem is that the 32 bit memory board from Intel bases itself at the
1 meg address boundary. So we have a 32 bit 512 on the "planar" and
lots of memory above 1 meg. How to fill? two ways, one get a 128k
memory board (hopefully 16 bit) or better yet do what I did
and find a memory board from an AT (that I had arround) that 
allows split addressing of its memory so you can fill the 128 k and
then put the rest up ABOVE the Intel boards. Unfortunately you can
NOT set the base memory on the 32 bit memory boards from Intel so
they stack at 1, 3 etc. I will look whose board I used NOT all allow
you to do this even though they say they support split memory.

Dave

ps WHY oh WHY did Intel do that!! 

pps BTW if you use SCO Xenix 386 it makes no difference anyway

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henderso@uoregon.UUCP (Mark C. Henderson) (09/12/87)

In article <8020007@hp-lsd.HP.COM> davek@hp-lsd.HP.COM (Dave Kumpf) writes:
>The latest issue of PC Magazine contains test reports on several '386 machines.
>They tested several which are based on the Intel motherboard, including Corvus,
>Kaypro, and others.  
>
>Here's my question -- the text implied that it is extraordinarily difficult
>(or impossible) to use more than 512K for DOS using the Intel motherboard,
>even if you have the Intel memory expansion cards.  What's the scoop? Anyone
>out there have any experiences with expanding DOS to 640K on the Intel
>board?
>
>Dave Kumpf -- hp-lsd!davek

Well, its not impossible, because I'm doing it, in a 386 clone, which
contains the Intel Motherboard. Computer Junction in Toronto (Canada)
sells a small board they call a "backfill" which fits into a 16 bit slot
and allows 640K for DOS. Basically its a small 128K memory board.  Their 
telephone number is 416-960-0300. They
regularly supply the board with their 386 clones. I forget the exact cost,
but it would be somewhere around $100.00 US. As far as I know, this is the
only solution.
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I hate to put in garbage to please the news program, but it is necessary.
I hate to put in garbage to please the news program, but it is necessary.
I hate to put in garbage to please the news program, but it is necessary.
I hate to put in garbage to please the news program, but it is necessary.
I hate to put in garbage to please the news program, but it is necessary.
I hate to put in garbage to please the news program, but it is necessary.
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