GeneveOS Device Operation

Accessing devices (floppy disk, hard disk, serial connector, printer) is possible in GeneveOS via XOP calls.

User-task XOPs

User-task XOPs are available for use in application programs. Here is a typical example:

PABADD EQU  >F180   
FILE   DATA 8
...
       LI   R0,PABADD
       XOP  @FILE,0
       MOVB @PABADD+2,R0
       JNE  ERROR
       ...

Similar as with the TI-99/4A device service routine concept (DSR), a Peripheral Access Block (PAB) must be set up prior to invoking the XOP.

Device Service Routine Call

	Input	Output
R0	Pointer to PAB	Pointer to PAB

The actual operation is contained in the Peripheral Access Block (PAB).