Keyboard: DOVIAE

       Name: DOVIAE                                                  [Show more]
       Type: Subroutine
   Category: Keyboard
    Summary: Implement the #VIAE <flag> command (enable/disable interrupts)
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * JMPTAB calls DOVIAE


 This routine is run when the parasite sends a #VIAE <flag> command. It updates
 the 6522 System VIA interrupt enable register (IER) at SHEILA &4E, which
 allows us to enable and disable interrupts. It is used for enabling and
 disabling the keyboard interrupt.


 Arguments:

   A                    The new value of the interrupt enable register (IER)


.DOVIAE

 STA VIA+&4E            \ Store A in SHEILA &4E

 JMP PUTBACK            \ Jump to PUTBACK to restore the USOSWRCH handler and
                        \ return from the subroutine using a tail call