There are ways to do it, but I've not found any that are as easy as it should be.
(1) Use FONTDEF to create your custom sideways / upside-down characters, then use GPUTCHR.
- or -
(2) Use GPUTCHR to display each character in normal orientation then use GSAVE to copy their pixels into an array, rotate the pixels within the array, then use GLOAD to write them back to the screen.
For each chr in the string, calc its location on screen, GSAVE the part of the screen that'll be behind it, rotate those pixels the opposite direction, then GLOAD them back to the screen, GPUTCHR the chr to the screen, GSAVE it, rotate it the right direction, GLOAD it back to the screen.
