GeneveOS Device Operation

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Revision as of 19:52, 22 July 2016 by Mizapf (talk | contribs) (Device Service Routine Call)
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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   
       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 -

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