Systems Reference Library - All about the IBM 1130 Computing ...

ATTENTION: This status indicates that the adapterhas accepted an XIO initialize read or XIO initializewrite from the 1800 and results in a condition codeof 1, status stored.DEVICE END: This status in response to a test I/Oindicates that a System/360 control commandaccepted by the adapter has been cleared by an XIOsense device from the 1800, but that device end hasnot yet been accepted by the System/360. Theresulting condition code is 1, status stored. Thetest I/0 clears device end from the adapter andleaves it idle.CHANNEL END AND DEVICE END: This status inresponse to a test I/0 indicates that a data transferoperation has been terminated, but that channel endand device end have not yet been accepted by theSystem/360. The resulting condition code is 1,status stored. The test I/0 clears channel end anddevice end from the adapter and leaves it idle.No-Operation (System/360)This command is handled by the adapter as an immediatecommand. The adapter response to thiscommand depends on the adapter status according tothe following rules.IDLE ADAPTER: An idle adapter accepts a nooperationcommand by responding to initial selectionwith channel end and device end. This responseresults in a condition code of 1, status stored. Theadapter does not save the command byte, nor doesit generate an interrupt to the 1800. Any commandbyte currently being saved by the adapter is notaltered by a no-operation command.BUSY ADAPTER: A System/360 no-operation commandmay be rejected because of any one of the followingadapter busy conditions:1. A System/360 no-operation command is issuedbefore a previous control command is clearedby an XIO sense device from the 1800. In thiscase, the adapter responds with busy. Thisresponse results in a condition code of 2, busy.2. A System/360 no-operation is issued after aprevious control command has been cleared, butbefore device end has been accepted by theSystem/360. In this case, the adapter respondswith busy and device end. This response resultsin a condition code of 1, status stored and clearsdevice end from the adapter, leaving the adapteridle.3. A System/360 no-operation command is issuedafter the adapter has previously accepted anXIO initialize read or XIO initialize write fromthe 1800. In this case, the adapter respondswith busy and attention. This response resultsin a condition code of 1, status stored. If theattention status was not previously accepted,this response clears that status. As a result,attention no longer attempts to interrupt theSystem/360. However, attention still appearsas a response to any no-operation commanduntil the previously accepted XIO initialize reador XIO initialize write has been satisfied.Halt I/O (System/360)A halt I/0 issued while the adapter is executing aSystem/360 read, read backward, write, or sensecommand causes immediate termination of the operation.The adapter responds with channel end anddevice end. This response results in a conditioncode of 2, burst operation terminated. If the 1800 isoperating with the adapter, it is signaled by a transferend and halt interrupt.A halt I/0 will be busy-rejected by the adapterif it is issued before a previous System/360 controlcommand has been cleared by an XIO sense devicefrom the 1800.A halt I/0 issued to an idle adapter results in a0 status response to the System/360 (conditioncode 1, status stored).1800 SYSTEM COMMANDSSystem/360 adapter operations are initiated by the1800 system by means of execute I/0 (XIO) instructions.The input/output control command (IOCC)referenced by an XIO must have an area code of01101 to address the System/360 adapter. Figure115 shows the IOCC's that may be used to controladapter operation. All other IOCC's are consideredinvalid and will be rejected by the adapter.After an XIO initialize read or XIO initializewrite has been accepted by the adapter, the controlword (area, function, and modifier) is available tothe System/360 by use of the sense command. Sincethe modifiers in these commands are ignored by theadapter, they may be used for communication withthe System/360 program.Sense Device (1800)This command causes the adapter device statusword (DSW) or word count to be read into the218