[fpc-pascal] Textmode IDE splitscreen?

Ralf Quint freedos.la at gmail.com
Mon Jul 25 14:32:03 CEST 2016

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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