1. xerox 560 computer system - The UK Mirror Service

Instruction NameDivide WordMnemonicDWAIADD IMMEDIATE(Immediate operand)Add Word to MemoryAWMModify and Test ByteModify and Test HalfwordModify and Test WordMTBMTHMTWThe va I ue fi e Id (bi t posi ti ons 12-31 of the i nstructi on word)is treated as a 20-bit, two's complement integer. ADDIMMEDIATE extends the sign of the value field (bit position12 of the instruction w~rd) 12 bit positions to the left,adds the resulting 32-bit value to the contents of register R,and loads the sum into register R.The fixed-point arithmetic instruction set performs binaryaddition, subtraction, multiplication, and division withinteger operands that may be data, addresses, index values,or counts. One operand may be either in the instructionword itself or may be in one or two of the current generalregisters; the second operand may be either in main memoryor in one or two of the current general registers. For mostof these instructions, both operands may be in the samegeneral register, thus permitting the doubling, squaring,or clearing the contents of a register by using a referenceaddress value equal to the R field value.Affected: (R), CC(R) + (I)12-31SE - RCondition code settings:2 3 4 Result in R- 0 0 Zero- 0 NegativeTrap: Fixed-point overflow,or nonexi stent i nstructionif bit 0 is a 1.All fixed-point arithmetic instructions provide a conditioncode setting that indicates the following information aboutthe result of the operation called for by the instruction:Condition code settings:2 3 4 Resultoo 0oZero - the result in the specified generalregister(s) is all zeros.Negative - the instruction has produced afixed-point negative result.o Positive - the instruction has produced afixed-point positive result.Fixed-point overflow has not occurred duringexecution of an add, subtract, or divide instruction,and the result is correct.o Positive- 0 No fixed-point overflowFixed-point overflowo No carry from bit position 0- Carry from bit position 0If AI is indirectly addressed, it is treated as a nonexistentinstruction, in which case the BP unconditionally abortsexecution of the instruction (at the time of operation codedecoding) and traps to location X'40' with the contents ofregister R and the condition code unchanged.If CC2 is set to 1 and the fixed-point arithmetic trap mask(AM) is a 1, the BP traps to location X'43' after loadingthe sum into register R; otherwise, the BP executes thenext instruction in sequence.oFixed-point overflow has occurred duringexecution of an add, subtract, or divide instruction.For addition and subtraction, theincorrect result is loaded into the designatedregister(s). For a divide instruction, thedesignated register(s), and CC1, CC3, andCC4 are not affected.No carry - for an add or subtract instruction,there \,ves no carrl of a l-bit cut of the h:ghorder(sign) bit position of the result.- Carry - for an add or subtract instruction,there was a l-bit carry out of the sign bitposition of the result. (Subtracting zero wi IIa Iways produce carry. )AHo 1 2ADD HALFWORD(Halfword index alignment)ADD HALFWORD extends the sign of the effective halfword16 bit positions to the left (to form a 32-bit word in whichbit positions 0-15 contain the sign of the effective ha!fword),adds the 32-bit result to the contents of register R,and loads the sum into register R.Affected: (R), CC(R)+EHSE-RTrap: Fixed-point overflow60 Fixed-Point Arithmetic Instructions