----------2102-------------------------------
INT 21 - DOS 1+ - WRITE CHARACTER TO STANDARD OUTPUT
         AH = 02h
         DL = character to write
Return:  AL = last character output
Notes:   ^C/^Break are checked, and INT 23 executed if pressed
----------2106-------------------------------
INT 21 - DOS 1+ - DIRECT CONSOLE OUTPUT
         AH = 06h
         DL = character (except FFh)
Return:  AL = character output
Notes:   Does not check ^C/^Break
----------2109-------------------------------
INT 21 - DOS 1+ - WRITE STRING TO STANDARD OUTPUT
         AH = 09h
         DS:DX = address of $ terminated string
Return:  AL = 24h
Notes:   ^C/^Break are checked, and INT 23 is called if either pressed
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