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APPENDIX C: INSTRUCTION SET AND INSTRUCTION TIMING OF 8086

APPENDIX C. INSTRUCTION SET AND INSTRUCTION TIMING OF 8086

  1. Instruction Set of 8086

    In this table, the complete set of instructions of the 8086 has been listed, with their mnemonic and function. For knowing the details (format and examples) of each of the instruction, the section in the text book, where they are discussed is given in the third column of the table.

    Data Transfer Instructions

    MnemonicFunctionSectionTable
    MOVMove byte or word to register or memory3.2.13.1
    IN, OUTInput byte or word from port, output word to port5.23.1
    LEALoad effective address3.2.23.1
    LDS, LESLoad pointer using data segment, extra segment3.1
    PUSH, POPPush word onto stack, pop word off stack3.2.43.1
    XCHGExchange byte or word3.1
    XLATTranslate byte using look-up table3.2.33.1


    Logical Instructions

    MnemonicFunctionSectionTable
    NOTLogical NOT of byte or word (one's complement)3.7
    ANDLogical AND of byte or word3.7
    ORLogical OR of byte or word3.7
    XORLogical exclusive – OR of byte or word3.7
    TESTTest byte or word (AND without storing)3.7


    Shift and Rotate Instructions

    MnemonicFunctionSectionTable
    SHL, SHRLogical shift left, right byte or word by 1 or CL3.6.13.8
    SAL, SARArithmetic shift left, right byte or word by 1 or CL4.7.33.8
    ROL, RORRotate left, right, byte or word by 1 or CL3.6.23.8
    RCL, RCRRotate left, right, through carry, byte or word by 1 or CL3.6.23.8


    Arithmetic Instructions

    MnemonicFunctionSectionTable
    ADDAdd byte or word3.4.23.4
    SUBSubtract byte or word3.4.33.4
    ADCAdd byte or word and carry3.4.23.4
    SBBSubtract byte or word and carry (borrow)3.4.33.4
    INCIncrement byte or word3.4.23.4
    DECDecrement byte or word3.4.33.4
    NEGNegate byte or word (two's complement)3.4
    CMPCompare byte or word (subtract without storing)3.4.43.4
    MULMultiply byte or word (unsigned)3.4.53.4
    DIVDivide byte or word (unsigned)3.4.63.4
    IMULInteger multiply byte or word (signed)4.7.23.4
    IDIVInteger divide byte or word (signed)4.7.23.4
    CBW, CWDConvert byte to word, word to double word4.73.4
    AAAASCII adjust for addition4.5.13.4
    AASASCII adjust for subtraction4.5.23.4
    AAMASCII adjust for multiplication4.5.33.4
    AADASCII adjust for division4.5.33.4
    DAA, DASDecimal adjust for addition, subtraction (binary coded decimal numbers)4.4.23.4


    Jump and Loop Instructions

    MnemonicFunctionSectionTable
    JMPUnconditional jump3.3.1 and 3.3.2
    JA (JNBE)Jump if above (not below or equal)3.3
    JAE (JNB)Jump if above or equal (not below)3.3
    JB (JNAE)Jump if below (not above or equal)3.3
    JBE (JNA)Jump if below or equal (not above)3.3
    JE (JZ)Jump if equal (zero)3.3
    JG (JNLE)Jump if greater (not less or equal)4.2
    JGE (JNL)Jump if greater or equal (not less)4.2
    JL (JNGE)Jump if less (not greater nor equal)4.2
    JLE (JNG)Jump if less or equal (not greater)4.2
    JC, JNCJump if carry set, carry not set3.3
    JO, JNOJump if overflow, no overflow4.2
    JS, JNSJump if sign, no sign4.2
    JNP (JPO)Jump if no parity (parity odd)3.3
    JP (JPE)Jump if parity (parity even)3.3
    LOOPLoop unconditional, count in CX3.3.3
    LOOPE (LOOPZ)Loop if equal (zero), count in CX3.3.3
    LOOPNE (LOOPNZ)Loop if not equal (not zero), count in CX3.3.3
    JCXZJump if CX equals zero3.3


    Call and Return Instructions

    MnemonicFunctionSectionTable
    CALL, RETCall, return from procedure4.2.2 and 4.2.3
    INT, INTOSoftware interrupt, interrupt if overflow8.3 and 8.2.5
    IRETReturn from interrupt8.1.1


    String Instructions

    MnemonicFunctionSectionTable
    MOVSMove byte or word string4.1.14.1
    CMPSCompare byte or word string4.1.24.1
    SCASScan byte or word string4.1.34.1
    LODS, STOSLoad, store byte or word string4.1.44.1
    REPRepeat4.1
    REPE, REPZRepeat while equal, zero4.1
    REPNE, REPNZRepeat while not equal (not zero)4.1


    Processor and Flag Control Instructions

    MnemonicFunctionSectionTable
    STC, CLC, CMCSet, clear, complement carry flag3.4.1
    STD, CLDSet, clear direction flag4.1
    STI, CLISet, clear interrupt enable flag
    LAHF, SAHFLoad AH from flags, store AH into flags3.1
    PUSHF, POPFPush flags onto stack, pop flags off stack3.1
    ESCEscape to external processor interface13.2.1
    LOCKLock bus during next instruction6.4.4
    NOPNo operation (do nothing)6.5.1
    WAITWait for signal on TEST input13.2.1
    HLTHalt processor6.3.5


  2. Instruction Timing of 8086

    1. Number of cycles expended in calculating the 'Effective Address'

      No.Addressing modeNo. of clocks for calculation of EA
      1Direct6
      2Register indirect5
      3Register relative9
      4Based indexed with BP as the base register8
      5Based indexed with BX as the base register7
      6Relative based indexed with BP as the base register12
      7Relative based indexed with BX as the base register11


    2. Number of clock cycles expended for each instruction of 8086

      CodeDescription8086
      AAAASCII adjust for addition8
      AADASCII adjust for division60
      AAMASCII adjust for multiplication83
      AASASCII adjust for subtraction8
      ADCAdd with carry
       reg to reg3
       mem to reg9+EA
       reg to mem16+EA
       immed to reg4
       immed to mem17+EA
       immed to acc4
      ADDAddition
       reg to reg3
       mem to reg9+EA
       reg to mem16+EA
       immed to reg4
       immed to mem17+EA
       immed to acc4
      ANDLogical AND
       reg to reg3
       mem to reg9+EA
       reg to mem16+EA
       immed to reg4
       immed to mem17+EA
       immed to acc4
      CALLCall a procedure
       intrasegment direct19
       intrasegment direct
       through register16
       intrasegment direct
       through memory21+EA
       intrasegment direct28
      CBWConvert byte to word2
      CLCClear carry flag2
      CLDClear direction flag2
      CLIClear interrupt flag2
      CMCComplement carry flag2
      CMPCompare
       reg to reg3
       mem to mem9+EA
       reg to mem9+EA
       immed to reg4
       immed to mem10+EA
       immed to acc4
      CMPS/Compare string/
      CMPSB/Compare byte string/
      CMPSWCompare word string
       Not repeated22
       REPE/REPNE CMPS/CMPSB/CMPSW9+22/rep
      CWDConvert word to doubleword5
      DAADecimal adjust for addition4
      DASDecimal adjust for subtraction4
      DECDecrement by 1
       16-bit reg3
       8-bit reg3
       memory15+EA
      DIVUnsigned division
       8-bit reg80–90
       16-bit reg144–162
       8-bit mem(86–96)+EA
       16-bit mem(150–168)+EA
      ESCEscape
       reg2
       mem8+EA
      HLTHalt2
      IDIVInteger division
       8-bit reg101–112
       16-bit reg165–184
       8-bit mem(107–118)+EA
       16-bit mem(171–190)+EA
      IMULInteger multiplication
       8-bit reg80–98
       16-bit reg128–154
       8-bit mem(86–104)+EA
       16-bit mem(134–160)+EA
      INInput from I /O port
       Fixed port10
       Variable port through DX8
      INCIncrement by 1
       16-bit reg3
       8-bit reg3
       mem15+EA
      INTInterrupt
       type=352
       type351
      INTOInterrupt if overflow
       interrupt taken53
       interrupt not taken4
      IRETReturn from interrupt32
      JA /Jump if above /16, noj 4
      JNBEJump if not below or equal
      JAE /Jump if above or equal16, noj 4
      JNBJump if not below/
      JNAJump if not above
      JCXZJump if CX is Zero18, noj 6
      JE/Jump if equal /16, noj 4
      JZJump if Zero
      JG/Jump if greater16, noj 4
      JNLEJump if not less, or equal
      JGE/Jump if greater or equal /16, noj 4
      JNLJump if not less
      JL /Jump if less/16, noj 4
      JNGEJump if not greater, or equal
      JLE/Jump if less or equal /16, noj 4
      JNGJump if not greater
      JMPJump
       intrasegment direct short15
       intrasegment direct15
       intersegment direct15
       intrasegment indirect
       through memory18+EA
       intrasegment indirect
       through register11
       intrasegment indirect24+EA
      JNE/Jump if not equal /16, noj 4
      JNZJump if not Zero
      JNOJump if not overflow16, noj 4
      JNP/Jump if not parity/16, noj 4
      JPOJump if parity odd
      JNSJump if not sign16, noj 4
      JOJump if overflow16, noj 4
      JP/Jump if parity/16, noj 4
      JPEJump if parity even
      JSJump if sign16, noj 4
      LAHFLoad AH from flags4
      LDSLoad pointer using DS/
      LESLoad pointer using ES16+EA
      LEALoad effective address2+EA
      LOCKLock bus2
      LODS/Load string/
      LODSBLoad byte string
      LODSWLoad word string
       not repeated12
       repeated9+13/rep
      LOOPLoop17, noj 5
      LOOPE/Loop if equal /
      LOOPZLoop if zero18, noj 6
      LOOPNE /Loop if not equal /
      LOOPNZLoop if not zero19, noj 5
      MOVMove
       acc to mem10
       mem to acc10
       reg to reg2
       mem to reg8+EA
       reg to mem9+EA
       immed to reg4
       immed to mem10+EA
       reg to SS/DS/ES2
       mem to SS /DS /ES8+EA
       segment reg to reg2
       segment reg to mem9+EA
      MOVS/Move string /
      MOVSB/Move byte string/
      MOVSWMove word string
       Not repeated18
       REP MOVS/MOVSB/MOVSW9+17/rep
      MULUnsigned multiplication
       8-bit reg70–77
       16-bit reg118–133
       8-bit mem(76–83)+EA
       16-bit mem(124–139)+EA
      NEGNegate
       reg3
       mem16+EA
      NOPNo operation3
      NOTLogical NOT
       reg3
       mem16+EA
      ORLogical OR
       reg to reg3
       mem to reg9+EA
       reg to mem16+EA
       immed to acc4
       immed to reg4
       immed to mem17+EA
      OUTOutput to I /O port
       fixed port10
       varible port8
      POPPop word off stack
       reg8
       segment reg8
       memory17+EA
      POPFPop flags off stack8
      PUSHPush word onto stack
       reg11
       segment reg:ES/SS/CS10
       memory16+EA
      PUSHDPush double flag onto stack10
      RCLRotate left through carry /
       Rotate right through carry /
       reg with single-shift2
       reg with variable-shift8+4 / bit
       mem with single-shift15+EA
       mem with variable-shift20+EA+4 / bnit
      RETReturn from procedure /
      RETFReturn far /
      RETNReturn near
       intrasegment16
       intrasegment with constant20
       intrasegment26
       intrasegment with constant25
      ROL/Rotate left
      RORRotate right
       reg with single-shift2
       reg with variable-shift8+4 / bit
       mem with single-shift15+EA
       mem with variable-shift20+EA+4 /bit
      SAHFStore AH into flags4
      SAL/Shift arithmetic left /
      SAR /Shift arithmetic right /
      SHL/Shift logical left /
      SHRShift logical right
       reg with single-shift2
       reg with variable-shift8+4/ bit
       mem with single-shift15+EA
       mem with variable shift20+EA+4 / bit
      SBBSubtract with borrow
       reg from reg3
       mem from reg9+EA
       reg from mem16+EA
       immed from acc4
       immed from reg4
       immed from mem17+EA
      SCAS/Scan string /
      SCASBScan byte string
      SCASWScan word string
       not repeated15
       REPE /REPNE SCAS /SCASB /SCASW9+15/rep
      STCSet carry flag2
      STDSet direction flag2
      STISet interrupt flag2
      STOS/Store string /
      STOSB/Store byte string /
      STOSWStore word string
       Not repeated11
       REP STOS/STOSB/STOSW9+10/rep
      STRStore task register
      SUBSubtraction
       reg from reg3
       mem from reg9+EA
       reg from mem16+EA
       immed from acc4
       immed from reg4
       immed from mem17+EA
      TESTTest
       reg with reg3
       mem with reg9+EA
       immed with acc4
       immed with reg5
       immed with mem11+EA
      WAITWait while TEST pin
       not asserted4
      XADDExchange and add
      XCHGExchange
       reg with acc3
       reg with mem17+EA
       reg with reg4
      XLAT/Translate11
      XORLogical exclusive OR
       reg with reg3
       mem with reg9+EA
       reg with mem16+EA
       immed with acc4
       immed with reg4
       immed with mem17+EA



  

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