Radio Shack TRS-80 Model II Reference Manual page 185

Technical Information
•
System Control
Supervisor calls described in this section:
FUNCTION
CODE NAME PURPOSE
0 INITIO
Initializes all I/O drivers
2 SETUSR
Sets up a user-defined SVC
3 SETBRK Sets up (BREAK) key processing program
15 DISKID Reads a diskette 10
25
TIMER Set timer to interrupt program
29 HLDKEY Process (HOLD)
36 JP2DOS Returns to
TRSDOS (TRSDOS REA.DY)
37
DOSCMD Sends
TRSDOS
a command and then
returns to
TRSDOS READY
38 RETCMD Sends
TRSDOS
a command and return
to caller
39 ERROR
Displays
"ERROR
number"
52 ERRMSG Returns Error Message to Buffer
57 CLRXIT Clear
RAM
and return to
TRSDOS
Table 4.3. System Control Supervisor Calls
INITIO
Initialize I/O (function code 0)
This routine initializes all input/output drivers.
It
calls all of the other
initialization routines. There are no parameters.
Note: This routine has been done already by the System. Users never need to
call it, except in extreme error conditions.
Error Conditions
A
=
0
Exit Conditions
NZ
=
Error
A = Error Code
221