IRO_ISN           912 src/dps8/dps8_cpu.h     word1 IRO_ISN; //  0    IRO       AVF Illegal Ring Order
IRO_ISN           501 src/dps8/dps8_faults.c     cpu . cu . IRO_ISN          = 0;
IRO_ISN           567 src/dps8/dps8_faults.c           cpu . cu . IRO_ISN   = 1;
IRO_ISN           760 src/dps8/dps8_faults.c     cpu.cu.IRO_ISN   = 0;
IRO_ISN           389 src/dps8/dps8_ins.c     putbits36_1 (& words[1],  0, cpu.cu.IRO_ISN);
IRO_ISN           664 src/dps8/dps8_ins.c 
IRO_ISN           390 src/dps8/panelScraper.c                 SETL1 (bank_a,  0+3, cpu.cu.IRO_ISN);