TLogicalScreenDescriptor = packed record
  ScreenWidth: word;
  ScreenHeight: word;
  PackedFields: byte;
  BackgroundColorIndex: byte;
  AspectRatio: byte;
end;

struct TLogicalScreenDescriptor {
  word ScreenWidth;
  word ScreenHeight;
  byte PackedFields;
  byte BackgroundColorIndex;
  byte AspectRatio;
};