DC_Pol, Poll for application or card usage

Register parameters

RST 20H, DEFW $220C
IN:
    A = card slot (0 to 3), 0 is internal
    or
    A7 = 1, test if application is active (IX = application static handle)

OUT:
    Fz = 0, No application active (in slot)
    Fz = 1, Application(s) is active (in that slot)

Registers changed after return:
    A.BCDEHL/IXIY same 
    .F....../.... different

Notes

Internal operating system usage.
A7 option added in OZ 4.6.
This routine is used by the card manager routine (part of the interruption code) to verify if there was a card before removal. It is the long bleep after an application card removal with active process.
It is used too by Index to prevent removal of an active application.

Related calls

OS_Poll, poll for an application
OS_Stk, stack the current process (application)
OS_Ent, enter an application
DC_Ent, enter new application
DC_Nam, name current application
OS_Exit, exit an application
OS_Bye, exit application
DC_Bye, exiting current application
OS_Use, process card usage
DC_Alt, pass an alternative character