Thanx
TJ
--
Thomas J. Smith @ MCC Software Technology
tsm...@mcc.com
sally!im4u!milano!tsmith
Such a conversion program interests me too. If such an animal exists can
someone perhaps post it to net.sources (assuming of course that its PD
software)?
Alan S. Fink
UUCP: {allegra, hocsd, philabs, ogcvax}!sbcs!asf
ARPA: asf%sunysb...@csnet-relay.ARPA
CSNET: a...@sunysb.edu
If the "graphic instructions to the CGA" are BIOS calls, then the
Hercules BIOS I posted to net.sources a few months ago will do the
trick. (Sort of. The aspect ratio won't be quite right, and the image
won't use the whole screen, but it'll work.)
However, the unfortunate fact is that VERY few programs use BIOS calls
for graphic output. Most write directly to display memory. Since
there's no display memory trapping on most PC-compatible machines
(read here, "practically all"), you have no way of trapping the
graphics instruction.
What MIGHT BE feasible is a "daemon" that runs from time to time,
and "fixes" the screen by some transformation. A few problems with
this are:
- Herc Board occupies different memory addresses from the CGA.
Unless you have a memory board that maps into the CGA address
space, you'll never capture the graphic writes.
- The algorithm would have to at least check (and maybe recompute)
the whole screen, often enough to look like a reasonably smooth
refresh. I bet that'd be a brutal drag on real-time performance.
- I don't know which would give better (less objectionable?)
images: using less than the full screen and an improper aspect
ratio, using a two-pixels-to-three "dithering" algorithm,
or using a one-pixel-to-two mapping and running off the edge
of the Hercules screen.
Good luck, and if you find a solution please post it.
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