073

Explanation
Initial program load (IPL) is waiting for an I/O
or external interrupt.
The right-most four bytes of the program
status word (PSW) have the following format: x0r00www
 where: x
Irrelevant information.
r
A hexadecimal reason code indicating the reason for the failure.
www
The wait state code.

 The reason code (r) is one of the
following: 1
IPL is waiting for an I/O interrupt.
2
IPL is waiting for an external interrupt.

System action
The system enters an enabled wait state.

Operator response
The wait time might vary between 30 seconds
and three minutes. If the system is still in a wait state after three
minutes, record the wait state PSW and inform the system programmer.

System programmer response
Take the following steps: Using the hardware Alter/Display facility, examine
the reason code in bits 40 through 43 of the wait state PSW. If the reason code is X'1', the system is waiting for
an I/O operation to complete. Continue problem determination with
step 2.
If the reason code is X'2', a hardware problem exists.
Have the operator retry the IPL. If the IPL is not successful, contact
hardware support.

If the reason code is X'1', the system is
waiting for an I/O operation to complete. This wait state indicates
that an I/O interrupt is outstanding. During IPL, I/O is done to either
the SYSRES volume or the IODF volume. The IPL program issues SSCH
to initiate the I/O, then loads a wait PSW that is enabled for I/O
(X'010A0000 00100073'). This PSW remains loaded until the
I/O interrupt comes in. If the I/O interrupt never comes in, the system
remains in a wait state. If the system is still in a wait state
after three minutes, have the operator retry the IPL. If the system
enters a wait state again for three minutes, you need to determine
whether a device or a path to the device is causing the problem. Continue
with the next step.

Using the hardware Alter/Display facility, read the 4-byte subchannel
address in central storage at X'B8'. The subchannel
number is the last two bytes (at location X'BA') of the 4-byte
subchannel identification word at location X'B8'.
Bring up the Device Configuration Display. Enter the 2-byte subchannel
number found in step 2. This displays
the device number, unit address, and one or more installed channel
paths to the device for the selected subchannel number. If there
is only one channel path to the device, the problem is caused either
by the path or by the device. There is no need for the system operator
to continue problem determination. Contact hardware support.
 If
there is more than one channel path to the device, configure offline
one path at a time and attempt to reIPL. If one of these IPL attempts
succeeds, the offline path is the failing path. If none of these IPL
attempts succeeds, the device is causing the problem.

It is likely that the failing path is the last path
used. Display subchannel status information. On CMOS-based processors,
this is the Analyze Subchannel Data display. Read the last path used
mask (LPUM) field to determine the last path used. The LPUM field
consists of 8 bits. If bit n is on, then CHPIDn is the last path used.
For example, if the LPUM field shows B'01000000', bit 1 is
on and the CHPID1 field identifies the last path used.
Bring up the CHPID menu and configure the last used channel path
offline.
ReIPL the system.
If the problem does not recur, you have identified the failing
path. If the problem recurs, continue attempting to reIPL the system
with one path configured offline. If one of these IPL attempts succeeds,
you have identified a failing path. If none of these IPL attempts
succeeds, the device is causing the problem. Contact hardware support.

Source
Initial program load (IPL)