IBM System/370 145 Manual page 150

for the 2540, are not defined for the 3505 and 3525, when an
equipment check occurs, the failing command, say a read, can be
reissued to attempt to correct the error. Equipment check is
considered to
be
a permanent error on the 2540.)
3. Retry after operator intervention. When the unit is readied
by
the operator after the indicated recovery action has been
performed, the ERP reissues the failing conunand. In this case,
the operator could have attempted to correct the error or could
have indicated that correction was not possible. If the error--a
card jam, for example--was corrected, processing should continue
normally when the failing command is reissued. However, if the
operator determines that correction is not possible, such as when
a card contains an invalid character, he can press the new
permanent error key on the operator panel. When the ERP reissues
the failing command after this key has been pressed, an error
condition results as soon as the reissued command is received,
and the appropriate sense byte is presented by the control unit
to indicate that the operator pressed this key. Permanent error
is then posted by the ERP without additional recovery action.
Implementation of the new permanent error key permits orderly
abnormal termination of a job step to take place when certain
uncorrectable failures occur. This key can also
be
used for operator
communication with a user-written error routine that is entered after a
permanent error occurs.
In order to pinpoint the specific recovery action to be taken when
operator intervention is required, both the 3505 and the 3525 have a new
backlighted panel as part of the operator panel. Buttons and lights on
the respective operator panels are illustrated in Figure 20.30.5. The
backlighted panel contains new lights, in addition to some of the same
lights that are on the 2540. Whenever operator intervention is needed,
the new operator call light goes on, together with one or more of the
lights on the backlighted panel. The lights identify the action to be
taken rather than.the error that occurred. For example, the check card
light, instead of a validity check light, goes on when a card should be
inspected for an invalid character or offpunching. There is also a
replace 1 light that goes on together with other lights for the
situation in which one card, instead of two, should be placed back in
the feed after a nonprocess run-out. If the operator wants or needs
even more explicit directions (for example, when more than one action
can be taken, as for a format mode reset condition), he can find written
directions in the error recovery procedure box, readily accessible under
the card joggler plate.
MAINTENANCE
A new approach to maintenance of the 3505 and 3525 has also been
taken that is designed to significantly reduce the time required to
diagnose and repair failures.
When a unit error occurs on a 3505 or 3525, sense byte 2, and 3 if
needed, is generated by the control unit for diagnostic purposes. Sense
byte 2 is coded to uniquely identify errorse Byte 2 also serves as a
pointer to the procedure to be taken as outlined in a new maintenance
document, called the Graphic Integrated Manual, for customer engineers.
This document contains iftformationthat currently is contained in
several CE documents, and i t is designed to pinpoint failures (and the
repair procedure required) without the use of an oscilloscope.
Resolution of the error through the use of sense byte 2 and the new
manual is designed to be such that nearly all errors can be diagnosed by
the CE without the use of OLTEP and OLT's.
140 A Guide to the IBM System/310 Model 145