INT 21 - DOS 1+ - DIRECT CONSOLE OUTPUT
AH = 06h
DL = character (except FFh)
Return: AL = character output (despite official docs which state nothing is
returned) (at least DOS 3.3-5.0)
Notes:  does not check ^C/^Break
writes to standard output, which is always the screen under DOS 1.x,
but may be redirected under DOS 2+
SeeAlso: AH=09h

See also: 2102

2106 - DOS 1+ - DIRECT CONSOLE OUTPUT