Diagnose Code X'24' -- Device Type And Features - IBM Professional Series User Manual

DIAGNOSE Code X'24' -- Device Type
and Features
DIAGNOSE Code X'24' requests CP to provide the virtual
machine with identifying information and status information
about a specified virtual machine device. The virtual
machine must specify the device address for which the
information is requested. CP returns information about that
device in the Rx, Ry, and Ry+ 1 registers. CP also provides
a condition code identifying the specific device information
returned to the virtual machine.
When a virtual machine issues DIAGNOSE Code X'24', the
Rx register must contain the virtual device address for which
information is requested or the values negative 1 or 2 (-1 or
-2). Specify -1 when the device is the keyboard/display
whose address is unknown to the virtual machine. Specify-2
when the device is the virtual machine printer whose address
is unknown.
When CP returns control to the virtual machine, the Ry,
Ry + 1, and Rx registers contain device information. The Ry
and Ry+ 1 register contain information about the device. If
-1 was specified, the Rx register contains the address of the
keyboard/ display. If -2 was specified, the Rx register
contains the address of the virtual machine printer.
The following diagrams identify specific information
returned by CP and show how to locate this information in
the Rx, Ry, and Ry+ 1 registers. The symbolic names used
in these diagrams are the symbolic names used with
VDEVBLOK, and RDEVBLOK in VM/SP Data Areas and
Control Block Logic.
A-16 VM/PC Users Guide