Tandy 1000 SL Technical Reference Manual page 523

Software
Upon return, AL contains the ASCII character and AH the keyboard
scan code.
Note: All registers except those used to return parameters to the
caller are saved and restored by the BIOS routines.
Following is a quick reference list of software interrupts for all device
I/O and system status services.
Service
Video Display
Equipment
Memory Size
Diskette
Serial Communications
System Services
Keyboard
Line Printer
Bootstrap Loader
System Clock
Software Interrupts
10 hex (16 dec)
1 1 hex (17 dec)
12 hex (18 dec)
13 hex (19 dec)
14 hex (20 dec)
15 hex (2ldec)
16 hex (22 dec)
17 hex (23 dec)
19 hex (25 dec)
lAhex (26 dec)
2.