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Mnemonic
Operand
Index
Time
Oper. Code
Address
Word
Microsec.
O F F
BNN
BNR
Description
12
OFF. All N register peripherals a r e logically discon-
nected from the N register, and the power supply for
the perforated paper tape punch is turned off.
12
BRANCH ON N REGISTER NOT READY.
The N
register is tested f o r the not-ready condition. Branch-
ing follows the normal branch instruction sequence.
12
BRANCH ON N REGISTER READY. TheN register i s
tested f o r the ready condition. Branching follows the
normal branch instruction sequence.
A U T O M A T I C P R O G R A M I N T E R R U P T
Automatic Program Interrupt (API) is an optional feature designed to control the simultaneous
operation of two o r more unrelated programs. When the API is s e t by programmed instruction,
the peripherals needed to process an additional program a r e allowed to interrupt the main program.
Information can be sent to, o r takenfrom, a peripheral. Then, while the peripheral is operating on
this information, control can be returned to the main program until the peripheral becomes "ready"
to send o r receive more information. The programmer can prevent the main program from being
interrupted through execution of a Priority Break instruction.
The API monitors the card reader, cardpunch, and the controllers connected through the numbered
priority control channels (magnetic tape, printer, document handler, m a s s random a c c e s s data
storage, and Datanet-15). An externaloff/on switchon the peripheral controller must be in the ON
position before that controller can interrupt the program through the API. This switch effectively
inhibits interruptions from main program peripherals.
The input/output typewriter and other N
register input/output devices cannot interrupt the program through the API.
A u t o m a t i c - P r o g r a m
I n t e r r u p t
I n s t r u c t i o n s
Mnemonic
Operand
1nde;
Time
0 p e r . C o d e
Address
Word
Microsec.
SET
SET
Description
PST
12
SET PRIORITY START. The Central P r o c e s s o r enters
the API mode, where it will remain until a SET PBK
instruction i s executed.
PBK
12
SET PRIORITY BREAK. The Central P r o c e s s o r leaves
the API mode and will not return until a SET PST
instruction i s executed.
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