b. VMFSTAT (displacement X'6S') contains the virtual machine
features. Value of !MFSTA! X'SO' X
i
40
i X'20' Value of VMMLVL2 --VSO' Comments iIrtual-block multiplexer channles
Autopoll handshake option in use User requested virtual timer request Co,!!!men!§ Receiving all informational messages
c. VMIOINT (displacement X'6A') contains the I/O interrupt pending
flag. Each bit represents a channel (0 through An
interrupt pending is indicated by a 1 in the corresponding bit
position.
d. Value of VMIOINT 10000000 00000000 01000000 00000000 00000000 00000001 Interrupt pending channel 0 Interrupt pending channel 1
Interrupt pending channel 15 VMIOACTV (displacement X'36') active channel is indicated
position.
is the active channel mask. An
by a 1 in the corresponding bit
The address of the VCHBLOK table is found in the VMCHSTRT field
(displacement X'1S') of the VMBLOK. General register 6 contains the
address of the active VCHBLOK. Examine the following fields:
1. The virtual channel address is contained in VCHADD (displacement X'OO'). 2. The status of the virtual channel is found in the VCHSTAT field
(displacement X'06'). The value of this field indicates the virtual
channel status: Value of VCHSTAT if80'-- X'40' X'01' Comments iIrtual-channel busy Virtual channel class interrupt pending Virtual channel dedicated
3. The value of the VCHTYPE field (displacement X'07') indicates the
virtual channel type: Value of VCHTYPE i'80'-- X'40' Comments iIrtual-selector channel Virtual block multiplexer Part 1. Debugging with VM/370 53

The address of the VCUBLOK table is found in the VCUSTRT field
(displacement X'1C') of the VMBLOK. General register 7 contains the
address of the active VCUBLOK. Useful information is contained in the
following fields:
1. The virtual control unit address is found in the VCUADD field
(displacement X' 00') • 2. The value of the VCUSTAT field (displacement X'06') indicates the
status of the virtual control unit: Value of VCUSTAT Feo'-- X'40' X'20' X'10' X'OS' X'04' comments iIrtuaI-subchannel busy
Interrupt- pending in subchannel Virtual control unit busy Virtual control unit interrupt pending Virtual control unit end pending Virtual control unit active
3. The value of the VCUTYPE field (displacement X'07') indicates the
type of the virtual control unit: Value of VCUTYPE X'SO,-- X'40' Comments iIrtual-control unit on shared subchannel Virtual control unit is a channel-to-channel
adapter
The address of the VDEVBLOK table is found in the VMDVSTRT field
(displacement X'20') of the VMBLOK. General register S contains the
address of the active VDEVBLOK. Useful information is contained in the
following fields:
1. The virtual device address is found in
(displacement X'OO'). the VDEVADD field
2. The value of the VDEVSTAT field (displacement X'06') describes the
status of the virtual device: Value of X'SO' X'40' X'20' X'10' X'OS' X'04' X'02' X'01' Comments iIrtuaI-subchannel busy Virtual channel interrupt pending Virtual device busy Virtual device interrupt pending Virtual control unit end Virtual device not ready Virtual device attached by console function VDEVREAL is dedicated to device RDEVBLOK