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

Branch and Link Long (PBALL)0 5 8 16 31Op Code Zeros Address0 1 0 1 0 XXX 0 0 0 0 0 0 0 0III! 1 1 1 1 1 1 1 _ 1 1 1 I 1 1 1 I 1 1 1 I 1 1 1-......„.....••■•■••■■•-■•■•-•■••••■••••..■•5 0-7 0 0 X X X XThe branch and link long instruction (PBALL) branches to another storage location andsaves the contents of the IAR for return to the original sequence. The PBALL instructionis unconditional; the branch is always taken because it is not based upon the result of acondition or test.When the second word of the PBALL instruction is fetched from storage, the IAR containsthe address of the storage location immediately following the PBALL instruction.Execution of the PBALL instruction causes the contents of the IAR to be stored (andthus saved for future use in returning to the original sequence) in the index registerspecified by the R field. If R=000, the accumulator is used for this purpose.The location of the next instruction to be executed (the location branched to) iscontained in the address field of the PBALL instruction. This address is loaded into theIAR and the branch is made to that address. The branch and link long instruction (PBALL)permits branching to any location in main storage, whereas the branch and link instruction(PBAL) limits branching to locations that are +127 or —128 storage positions away fromthe address contained in the IAR when the PBAL instruction is executed.Bits 8 to 15 of the instruction must always be set to 0's.The branch and link long instruction does not change the carry, overflow, and resultindicators.