On 7/25/2016 5:06 AM, James Richters wrote:
The TurboPascal version used to write to B800-B7FF for the monochrome monitor and A000-AFFF for the color monitor, the IDE was always on monochrome and the program executing was always on color... that's how it worked,
No, it didn't.
The monochrome screen RAM is at segment address $B000 and while a whole 32KB is reserved ($-B7FF), only the first 4KB are in fact used. (80x25 characters, 2 bytes per character=4000 bytes) The Hercules graphics card did use the whole 32KB when in graphics mode.
The default page for color text mode (mode 3) starts at $B800, is also 4KB and a total of 8 pages are available up to $BFFF, though an original CGA card had only 16KB and hence only the first 4 pages are available.
And it was a choice which screen appears on which monitor, selectable as a parameter upon start of the IDE. I in fact used to run most of the time with the IDE on the color screen and the program output on the monochrome screen, unless I would explicitly test a program with color screen features.
$A000 is the start of the EGA/VGA graphics screen, not a text screen segment address...
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