The 640k "barrier" (was: Re: cctalk Digest, Vol 44, Issue 54)

Chuck Guzis cclist at
Mon Apr 23 19:18:47 CDT 2007

On 23 Apr 2007 at 15:51, Chris M wrote:

>  But a '186 is merely an '86 with some other chips
> tacked on. I don't know how V-8086 handles "additions"
> as it emulates a peecee on a windows box, but it at
> least seems that you could "add" on the ancillary '186
> functionality in the same way you add the other
> components present on a peecee mobo. 

Yes, you probably could.  The big problem that I see is while the 
386/486/Pentium V86 mode is close to what an 80186 does, there are 
differences (itemized in the V86 mode description).  They may not 
make any difference, but if they do, you're out of luck.
Plus, setting up a V86 session is pretty involved.  You need to have 
a protected mode server for the V86 session and set up all of the 
IDT/GDT/LDT stuff that goes along with it.  It feels like a lot of 
work to me, but I could be mistaken.

I'm assuming that you're going to host this thing on DOS; I don't 
know what provisions for V86 mode are built into Linux (never had a 
reason to look), but maybe that might be easier.


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