------| Atari XL as usb keyboard |-----
       
       SIO2Arduino is used as disk emulator and later extended to allow
       serial communication to a host pc. Translation code was added to
       convert atari key codes to ps2 keycodes. 
       
       XLK08.BAS
       atari basic program to send key strokes to the SIO2Arduino hardware
       
       900 KCNT=3
       910 EOL=155
       920 AADR=753
       930 KADR=764:POKE (KADR),255
       940 OPEN #1,8,0,"P:"
       950 K=PEEK(KADR):IF K=255 THEN 950
       960 POKE (KADR),255
       970 PUT #1,K:PUT #1,EOL
       980 IF K=39 THEN 1010
       990 PUT #1,K:PUT #1,EOL
       1000 GOTO 950
       1010 ON PEEK(AADR)=3 GOTO 1010
       1020 PUT #1,K:PUT #1,EOL
       1030 GOTO 950
       
       XLK09.BAS has the following change in line 900
       900 CLOSE #1:KCNT=3
       910 EOL=155
       920 AADR=753
        ...
       
       adding CLOSE #1 allows me to interrupt and add more code and then r
       the keyboard program without errors
       
       original codes are based on the following source
 (HTM) https://github.com/whizzosoftware/SIO2Arduino
       
       notes ====
       to display basic listing on a unix terminal
       cat PROGRAM.BAS | tr '\233' '\n'
       
 (DIR) ..                                                                
 (TXT) SIO2Arduino.diff                      2018-May-29 15:28    44.1 KB
 (TXT) intro                                 2018-Jun-06 14:58     0.8 KB