Tandy 1000 HX Technical Reference Manual page 392

Below is a quick reference list of software interrupts for all
device I/O and system status services.
Service Software Interrupts
Keyboard 16 hex (22 dec)
Video Display 10 hex (16 dec)
Serial Communications 14 hex (20 dec)
Line Printer 17 hex (23 dec)
System Clock 1A hex (26 dec)
Floppy Disk 13 hex (19 dec)
Equipment 11 hex (17 dec)
Memory Size 12 hex (18 dec)