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360 Issues Initial Status PresentedRead orRead BackwardIdl , 360 Control 1800 Read 1800 WriteZeroChanneEndBusy andAttentionZeroWrite Zero Zero Busy andAttentionBusy andControlDevice End*No-OperationChannelEnd andDevice EndBusy andAttentionBusy andAttentionBusy andAttentionBusy andAttentionSense Zero Zero ZeroTest I/O Zero Busy orDevice End* Attention Attention* Device End is conditionalFigure 11 7. System/3 60 Status Summaryduring the ending sequence for all othercommands.123411AIDEVICE END: The adapter presents device end tothe System/360 during initial selection for a nooperationcommand, after an XIO sense device fromthe 1800 in response to a control command, or withchannel end at the end of data transfer for all othercommands.Adapter Device Status Word (1800)Figure 118 shows the format of the adapter devicestatus word (DSW) read into the accumulator by anXIO sense device with modifier bit 8 off. Interruptindicators and program resettable indicators arealso defined.COMMAND REJECT: This indicator turns on, causingan interrupt, if the adapter rejects an 1800 XIOfor any one of the following reasons:1. The input/output control command referencedby the XIO has an invalid function code.2. An XIO initialize read or XIO initialize write isgiven before a previous XIO initialize read orXIO initialize write is cleared.3. An XIO initialize read is given after the adapterhas accepted a read, read backward, or controlcommand from the System/360.4. An XIO initialize write is given after the adapterhas accepted a write or control command fromthe System/360.If command reject occurs while the adapter does nothave an 1800 command stored, the adapter wordcount is reset to its maximum value. Such a resetcan occur when transfer end has been generated butnot yet accepted by the 1800.1800 COMMAND STORED: This indicator turns onwhen the adapter accepts an XIO initialize read orXIO initialize write from the 1800, and remains onuntil reset by transfer end.360 COMMAND STORED: This indicator turns onwhen the adapter accepts a read, read backward,write, or control command from the System/360.If the command is read or write, this indicatorcauses an interrupt to the 1800 unless suppressed bythe S-bit being on in the command byte or a complementarycommand from the 1800 waiting in theadapter. The interrupt condition can be reset by anXIO sense device with modifier bit 8 off and modifierbit 15 on. However, the 360 command storedindicator remains on until transfer end occurs.If the command is read backward, the responseis identical to a read command described in the precedingparagraph, except that the interrupt to the1800 cannot be suppressed by the S-bit in the commandbyte.If the command is control, the 360 commandstored indicator causes an interrupt to the 1800. Inthis case, the indicator is reset by an XIO sensedevice with modifier bit 8 off and modifier bit 15 on.The 360 command stored indicator can be on atthe same time as transfer end. This indicates thatthe adapter has accepted a new command from theSystem/360.0 2 3 6 7 8 9 10 II 12 13 14 15* Interrupt360 Command ByteIndicator Name7 End of Table *#6 Transfer End *05 Storage Protect Violation *04 Data Check *03 Halt *02 360 Command Stored *•1 1800 Command Stored •0 Command Reject *#0 Indicator reset by an XIO sense device with reset• Indicator reset by transfer end. 360 command stored reset by X10 sensedevice with reset if command is a control commandFigure 118. System/3 6 0 Adapter Device Status Word123408AISystem/360 Adapter 221