The 640k "barrier" (was: Re: cctalk Digest, Vol 44, Issue 54)
cclist at sydex.com
Sun Apr 22 10:59:14 CDT 2007
On 22 Apr 2007 at 8:23, Chris M wrote:
My question is therefore is this practical
> or even feasible? My guess is it's possible, but some
> code could be so convoluted that it would be extremely
> difficult. In essence the software would need enough
> intelligence to reverse engineer another bunch of
> code. Could it be done totally by automation...
I suppose it all depends if you're talking about text or graphics.
Text is pretty simple, but graphics bit- and port-level compatibility
is a different matter. Still, it's possible to search an app for
video display buffer segment loads and alter them. Recall that many
apps would work on both MDA/MGA and CGA and so altered which addess
that was used on the fly. Note that apps that used CGA 80x25 text
may not work without more probing as a "stall" waiting for the
retrace interval to avoid snow in the display was very commonly used
and may well cause your application to hang without modification.
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