simulate VGA on HERC using BGI driver

[Ed Howland]

SRGXNBS at grace.dsir.govt.nz writes:

>I've got a cad program I use at work which requires EGA/VGA, I'd also
>like to run it at home but only have a herc screen. The program uses
>a BGI driver .. I was wondering if it would be possible to "fake" VGA
>by writing an EGA/VGA simulation .BGI driver for a hercules screen? It
>would also require a pop-up facility to adjust the colour->monochrome
>translation on the fly. Most cad (electrical) is 2D anyway so I should
>be able to operate the program (EAGLE by CadSoft) ok.
>Any help/comments etc. appreciated ....
>bruce

I presume that you have  some ability to change the driver that is loaded
with the .EXE, since you say you want a new .BGI file. You should not have
to create a new one, just use the herc  .BGI and link to (using BIN2OBJ.EXE)
the cad software. If the calling software has properly initialized the loaded
driver (via registerBGIdriver()) or autodetect, it should convert the 
coordinates, color map, etc. If the calling software makes some non-standard
assumptions about the hardware, or explicitly loads the EGA/VGA driver (no
autodetect) then you might have to fake the EGA/VGA itself. Borland (I think)
sells a driver development kit. Or I once heard about it being available
somewhere.
Ed.
-- 
Ed Howland
internet: eeh at dixie.com
uucp:     ..[emory,uunet]!rsiatl!eeh