INT 0x21 - 0x02 - Write character to standard output

Request/Call:

reg	value	descr
AH	0x02
DL		Character to output

reg	descr
AL	last character output (despite the official docs which state nothing is returned) (at least DOS 3.3-5.0)

^C/^Break are checked, and INT 23 executed if pressed standard output is always the screen under DOS 1.x, but may be redirected under DOS 2+
the last character output will be the character in DL unless DL=09h on entry, in which case AL=20h as tabs are expanded to blanks