| Atari 400/800/XL/XE/XEGS systems |
· 2 different versions of the OS exist, referred to as “A” and “B”.
· To determine if your computer uses the original CTIA graphics chip or the upgraded GTIA, enter “POKE 623,64”. If the screen stays the normal blue it has the CTIA; if turns gray/black it has the GTIA.
· XL/XE software won't work on 400/800 if: {Konrad M.Kokoszkiewicz}
1) it uses shadow RAM at $C000-$CFFF and $D800-$FFFF
2) it uses RAM expansions at $4000-$7FFF controlled by
PORTB $D301 br>
3) it uses specific XL OS functions (like JNEWDEVC)
4) it uses illegal XL OS addresses.
5) it uses European Charset
· BUG: The operating system has an inherent flaw in the S: handler routine. For example, using certain (S: handler) values meant for use by the E: handler, such as 155 (EOL/line feed) and 125 (clear-screen) end up being interpreted by the S: handler instead. The following BASIC program illustrates this problem:
1 GR.15+16
2 COLOR 125: PLOT 0,125:DRAWTO 50,125
3 COLOR 155: PLOT 0,155:DRAWTO 50,155
4 GOTO 4
If the COLOR values are changed to 1 and 2 respectively, you’ll see that the programs original intention was to draw 2 differently-colored horizontal lines.
