MobyGamer/total-dos-launcher

Mono display attributes and number of screen lines wrong on Leading Edge Model D set to Hercules mode

MobyGamer opened this issue · 2 comments

On a pure Hercules system (Leading Edge Model D with monochrome screen running MS-DOS 3.1), two bugs were observed:

  • Number of screen lines was incorrectly determined. Thought it had 200+ lines and the screen didn't repaint properly. Code review required.
  • The display attribute for the file dialog resulted in a border drawn with underlined graphics characters.

BIOS in that system somehow puts 4000h bytes as part of a text screen when it should be 80x25. As a result, the calculations go horribly wrong. This was addressed by adding code to adjust to 25 if things look really wrong.

Code in question that was adjusted was TPLibs/TOTT/TOTSYS.PAS. MobyGamer/TPLibs@2c9c37f has the details.