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

Interrupt Status Word Extension (ISWEX)Some I/O devices or modules cannot present enough status information in one 16-bit word,so a second status word, called interrupt status word extension (ISWEX) is used. Conditionsthat set any ISWEX indicator bit also set a bit in the ISW for that device or module.An ISWEX can be read with the following command:0 5 8 11 16 20 26 31Op code R Fun Zeros Mod DA MA0 0 0 0 1 XXX 0 1 0 0 0 0 0 0 1 0 1 1 XXXXXXXXXXXXiiii ii II 11 1 1 ill i 1 1 1 1 1 111 1•■111.,./.111•••••■••••,,.■••••■••••,,■V*••••■••••••••0 8-F 4 0 B X X XThis command stores 16 bits of status information into the index register specified by R,or the accumulator if R=000. Each I/O device that employs an ISWEX determines thecondition(s) that set any particular bit. These conditions are defined in the chapter thatdescribes the specific I/O device concerned. (Bits not used by the device are set to 0.)Direct Control Channel Status WordErrors may be detected during the execution of immediate commands to devices attacheddirectly to the processor module (for example, timers, operator station, AsynchronousCommunications Control attachment or Binary Synchronous Communications Adapter).Such errors will cause certain direct control channel status bits to be set on or off. Errorsdetected by such commands cause condition code 1 to be returned to the processor module.This condition code is returned to any subsequent I/O commands addressed to the processormodule until the status word is reset.The direct control channel status word is read and reset by an immediate read commandsimilar to the read DSW command as follows:0 5 8 11 16 20 26 31Op code R Fun Zeros Mod DA MA0 0 0 0 1 XXX 0 1 0 0 0 0 0 0 **** 0 1 0 0 0 0 0 0 0 0 0 0iiii II 1 1 MI t I 1 i I 1 1 1 111 1 1••■■••Ne.r.r'',rN,,.....,■•■••semn."'"■•••••sr."'''''•• •••*v■••••••■•••■■•u"''''■•■•••■■•'•■•••■■'••••••0 8-F 4 0 0 4 0 0This command stores the status word in the index register specified by the R field, or theaccumulator if R=000.The status word is reset when read by the above read command or by system reset.Significant bits in the direct control channel status word and their meanings follow.(Bits not used by the direct control channel are set to 0.)Processor Instructions 4-61