1. xerox 560 computer system - The UK Mirror Service

The functions of bits within the DC status byte (which areunique to the device and device controller) are describedin applicable peripheral reference manuals. The functionsof other bits in the Ala _response word are described inTables 18, 19, and 20.The Ala instruction resets the interrupt request signal forthe I/O subsystem responding to the Ala (i.e., I/O subsystemidentified by bits 19-31 of register R).Affected: (R), CCIf CC4 = 0, the MIOP is operating in a normal mode ofoperation and thecondition code settings for Ala areshown below:2 3 4 Result of Alao 0 0 0 Normal interrupt recognized and reset.Status information in general register iscorrect.o 0 0 For RMP, normal interrupt recognized andreset; status information in the general registermay be incorrect. For MIOP, notpossible. Parity error on returned statusand/or condition code. The result of theAla is indeterminate.o 0 Processor interface detected.o 0 0 Unusual condition interrupt recognized andreset. Status information in general regis­Tel is (;orrecT.2 3 4 Result of Alao 0 For RMP, unusual condition interrupt recognizedand reset; status information in the generalregister may be incorrect. For MIOP,not possible.1 0 0 0 Interrupt recognized and reset. Status informationnot returned.o 0No I/O device requesting an interrupt andno status information returned to the generalregister.o Not possible.If CC4 = I, the MIOP is in the test mode and the meaningof the condition code during an Ala is:2 3 4 Meaning0 0 0 Unit is performing an Order Out operation.0 0 Unit is performing an Order In operation.0 0 Unit is performing a Data Out operation.0 Parity error detected by Processor Interface.0 Unit is performing a Data In operation.BCF detected while unit is performing a Datain operation.Input/Output Instructions 141