IBM System/7 Functional Characteristics - All about the IBM 1130 ...

Digital Input Groups Without Process Interrupt Feature: In latched mode, operation isthe same as in unlatched mode except under these two conditions.1. Whenever the following sequence of instructions is issued, two successive read/resetdigital-input-register commands must be issued to restore the digital input circuitsto their original status:—Set-digital-input-latch-control (bit 15=1).—Set-test-signal (bit 15=1).—3-microsecond delay.2. The following sequence of instructions results in reading the user's input value insteadof reading all O's:—Set-digital-input-latch-control (bit 15=1).—Set-test-signal (bit 15=0).—3-microsecond delay.Digital Input Groups With Process Interrupt Feature: In latched mode, operation is thesame as unlatched mode except under the following conditions:When any of the user's input signals are in the logical 1 state at the same time that a setdigital-input-latch-controlcommand is issued (bit 15=1) followed by a set-test-signal-to-l'sinstruction, a read-digital-input-register command or a read/reset-digital-input-registercommand will read l's for all bits whose inputs were at the logical 0-state.Note. If the sequence of commands is such that a set-test-signal command (bit 15=0 orbit 15=1) is followed by a mode change (latched to unlatched or unlatched to latched),the digital input register is set to the all 0's state.Read ISW0 5 8 11 16 20 26 31Op code0 0 0 0 1 X X XFun0 1 01 101Zeros0 0 01 10IMod0 0 1I I1IDA0 0 0 X 0 0I'll!MAXXXXXXI I I 1 10 8-F 4 0 3 0 or 1 0-3 XThis command stores a 16-bit interrupt status word (ISW) into the index register (R), orthe accumulator if R=000.13-20 GA34-0003Interrupt Status Word (ISW): No ISW is associated with the digital input function unlessthe process interrupt feature is installed. For each process interrupt feature (maximumof two), there is a separate ISW, one for each group with interruption capability.The setting of ISW bits (except the busy bit) is indicated to the operating programby an interruption request. Interruption requests are presented because of errors detectedin digital input operations, as well as for the occurrence of a process interrupt.A read ISW command also resets the addressed ISW. The significant bits in the ISW andtheir meanings are:Significant Bits Meaning3 Open circuit. A digital input circuit breaker has opened during thetime that the corresponding digital input group is busy. This conditionresults in an interruption request.12 Device busy. Digital input group 0 or 1 was addressed and that groupis in an interruption-enabled state. (See "Set Digital Input InterruptControl" previously described in this chapter.) The resultinginterruption on equal or unequal comparison turns off this bit andturns on the device-end bit.13 Device-end. A successful compare on equal or unequal has occurredfor group 0 or 1. This causes an interruption request and disablesinterruptions for that group.11111111111111MAii II