IBM 3745 Series, Hardware Maintenance Reference

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Summary of Actions Taken During AIOs and PIOs
Event Action In
AIO for Program AIO for MOSS IOH/IOHI MIOH
AIO stop (by
MOSS)
SP/AE violation
Add. compare
stop
Adapter bus
error (wo add.
bus check stop
mode)
Hard check
Mask ch.req. *
Halt to add.
level 1
Mask ch.req. *
Halt to add
level 1
Halt to add
mask ch.req. *
mask ch.req. *
Halt to add
HLIR to MOSS
Mask ch.req. *
Halt to add
HLIR to MOSS
Halt to add
mask ch.req. *
Mask ch.req. *
Level 1 (when I
fetch)
Mask ch.req. *
Halt to add
level 1
Halt to add
mask ch.req. *
Mask ch.req. *
Not available
Not available
Halt to add
HLIR to MOSS
Halt to add
Mask ch.req. *
* "Mask ch.req." means "Mask channel request" for AIOs, that is, AIO stop is set.
MOSS Interconnection Type Errors
MOSS Interconnection Parity Error
Ÿ Parity error detected either on MOSS address bus or on MOSS data bus during
a write operation.
Ÿ Parity error detected on MOSS address bus during a read operation.
MOSS OP Error: Moss initiates an indirect operation while the CCU busy bit is
ON, meaning that CCU resources are already used for a previous MOSS indirect
operation.
MOSS Address Exception Error: MOSS attempted to read or write storage
which is not installed.
Handling
These errors result in a high-level interrupt to MOSS (for MOSS OP error and
MOSS address exception error), or in a signal returned to MOSS through an inter-
face line (for MOSS interface parity error).
Chapter 2. Central Control Unit (CCU)
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