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Material Type: Notes; Professor: Bosworth; Class: Computer Architecture; Subject: Computer Science; University: Columbus State University; Term: Unknown 2004;
Typology: Study notes
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Of the possible 32 opcodes, only 26 are implemented. Op-Code Mnemonic Description 00000 HLT Halt the Computer 00001 LDI Load Register from Immediate Operand 00010 ANDI Logical AND Register with Immediate Operand 00011 ADDI Add Signed Immediate Operand to Register 00100 NOP Not Yet Defined – At Present it is does nothing 00101 NOP Not Yet Defined – At Present it is does nothing 00110 NOP Not Yet Defined – At Present it is does nothing 00111 NOP Not Yet Defined – At Present it is does nothing
Op-Code Mnemonic Description 01000 GET Input from I/O Device Register to Register 01001 PUT Output from Register to I/O Device Register 01010 RET Return from Subroutine 01011 RTI Return from Interrupt (Not Implemented) 01100 LDR Load Register from Memory 01101 STR Store Register into Memory 01110 JSR Call a subroutine. 01111 BR Branch on Condition Code to Address
Unary Register-To-Register 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 – 0
Syntactic Sugar Assembled As Comments CLR %R2 LDI %R2, 0 Clears the register CLW X STR %R0, X Clears the word at address X INC %R2 ADDI %R2, 1 Increments the register DEC %R2 ADDI %R2, -1 Decrements the register NOP LLS %R0, %R0, 0 No-Operation: Does Nothing RCS %R3, %R1, 3 LCS %R3, %R1, 29
DBL %R2 LLS %R2, %R2, 1 Left shift by one is the same as a multiply by 2. MOV %R2, %R3 LSH %R2, %R3, 0 Shift by 0 is a copy. NEG %R4, %R5 SUB %R4, %R0, %R5 Subtract from %R0 0 is the same as negation.
Syntactic Sugar Assembled As Comments TST %R1 SUB %R0, %R1, %R
BRU BR 000 Branch always BLT BR 001 Branch if negative BEQ BR 010 Branch if zero BLE BR 011 Branch if not positive BCO BR 100 Branch if carry out is 0 BGE BR 101 Branch if not negative BNE BR 110 Branch if not zero BGT BR 111 Branch if positive