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

Example: Assume that the PBALL instruction is at storage locations 87 and 88.0 5 8 16 31PBALL instructionOp code0 1 0 1 01 illR1 1 1ii0 0101 1Zeros0 101 I0 01010 0 0 00 1IAddress0 01 0 0 11 1 101 I0 0 1 01 1 1570 0 0 4 2 20Index register 7150IAR15PBALL instructionis fetchedX••■■■••,...."X XX0 01(Decimal 89)0 0 i 0 0 0 0 0 1 01 1 11 1 I 1 1 11 1 110I0 0 5 90 11 IIAR storeby p BALL= instruction =—0 15PBALL instructionexecution(Decimal 89)0 0 0 0 1 0 0 0 0 10 1 0 1 11 0 0 11 1 1 1 1 1 1 1 1 1 1 1 I II0 0 5 90 15 0IAR15After PBALLinstruction execution(Decimal 89) (Decimal 1058)0 0 0 0,0 0 0 0 1 0 1 0 1 1 1 0 0 1 0 0 0 0 0 1 0 0 0 0 1 0 0 0 1 01 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 10 0 5 9 0 4 2 2The IAR contains the effective address of the next instruction to be executed; that is,the instruction branched to, which is at location 1058. The branch to location 1058 istaken and execution begins.When it is desired to return to the original sequence (at location 89), the contentsof index register 7 must be moved to the IAR. A branch (PB) instruction, with 0displacement and R=111 (specifying XR7), can be used to accomplish this.Processor Instructions 4-33