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

I i 1111111'1Np■I0111m PIP ,ili111.111II 'Ail, II pp IlOIAi 1141111111.111.11FIIIIIIIIPUILOGICAL INSTRUCTIONSA logical instruction is one that is defined in symbolic logic, such as AND, OR, andexclusive OR_Six-instructions are provided to perform logical operations with data instorage and/or the index registers or the accumulator. Two words of data are used by theseinstructions in order to produce a one-word logical result.AND (PN)0 5 8 15Op code R1 1 1 0 0i III X X X1 1DisplacementE 0-7 X XThe contents of the accumulator are ANDed, bit by bit, with the contents of the storagelocation specified by the effective address. The result replaces the contents of theaccumulator. The contents of the addressed storage word are not changed.An R field of 000 means that the effective address of the storage data is generatedusing the IAR as the base register.The carry and overflow indicators are not changed. The result indicators are changedto reflect the fmal contents of the accumulator.ANDing occurs only between corresponding bits in the accumulator and the storage word:bit 0 is ANDed only with bit 0, bit 1 only with bit 1, and so on. The four possibleANDing combinations are:Bit Value fromStorage WordBit Value fromAccumulator0 0 00 1 01 0 01 1 1Result inAccumulatorThus, a bit value of 1 will result in the accumulator only if a . corresponding bit positionis set to a value of 1 in both the accumulator and the storage word.Example:Word in accumulatorWord from storageResult in accumulator01 01 0000 1111 101 01010 1111 1010 11110000 0000 1010 1010OR (P0)05 8 15Op code R1111 X1 1 1 0 1X X1 1DisplacementE 8-F X XThe contents of the accumulator are ORed, bit by bit, with the contents of the storagelocation specified by the effective address. The result replaces the contents of theaccumulator. The contents of the addressed storage word are not changed.4-20 GA34-0003