IBM 1 Series - Interrupt Presentation; Operations

Interrupt Presentation
The teletypewriter adapter requests an interrupt (if it has been properly
prepared) under the following conditions:
e When a normal receive operation is completed
e When an overrun receive operation is completed
e When a transmit operation is completed
Condition codes (CCs) reported at interrupt-acceptance time are as
follows:
CC value Meaning
Exception
Device end
Attention
Attention and exception
Attention and device end
SA
BW
WN
The interrupt condition codes are subject to the following rules and
considerations:
e The attention and exception codes are associated only with receive
operations. The device-end code is associated with a transmit
operation.
e The attention and exception codes are associated with operations
initiated by the device. The device-end code is associated with
operations initiated by the program.
« Attention and exception interrupts may be posted asynchronously to
the device-end interrupt. Since interrupt-code presentation does not
accommodate both exception and device-end codes during interrupt
presentation, the exception code takes precedence over the device-end
code at interrupt-presentation time if both interrupts have been posted.
The presentation and acceptance of the exception code does not reset
a pending device-end interrupt.
The meanings of the interrupt condition codes are as follows:
CC2 Indicates that the adapter has detected at least one overrun receive
operation. A device-end interrupt may be pending, but the
exception code has taken precedence in presentation.
CC3_ Indicates completion of a transmit operation as a result of a Write
command or indicates completion of an IPL operation. No
exception interrupt has been posted at accept time.
CC4 Indicates completion of a normal receive operation.
CC6 Indicates that the adapter has completed a normal receive operation
and has completed at least one overrun receive operation. A
device-end interrupt may be pending, but the exception code has
taken precedence in presentation.
CC7 Indicates that the conditions that cause CC3 and CC4 have
occurred.
A detailed description of the differences among condition codes 2, 4, and
6 can be found in the IBM Series/1 processor description manuals. Refer
to the Preface of this manual for titles and order numbers.
4-14 GA34-0033