The Intel 8086 / 8088/ 80186 / 80286 / 80386 / 80486 Instruction Set
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J Instructions

Jxx - Jump Instructions Table 

        Mnemonic              Meaning                    Jump Condition

          JA     Jump if Above                         CF=0 and ZF=0
          JAE    Jump if Above or Equal                CF=0
          JB     Jump if Below                         CF=1
          JBE    Jump if Below or Equal                CF=1 or ZF=1
          JC     Jump if Carry                         CF=1
          JCXZ   Jump if CX Zero                       CX=0
          JE     Jump if Equal                         ZF=1
          JG     Jump if Greater (signed)              ZF=0 and SF=OF
          JGE    Jump if Greater or Equal (signed)     SF=OF
          JL     Jump if Less (signed)                 SF != OF
          JLE    Jump if Less or Equal (signed)        ZF=1 or SF != OF
          JMP    Unconditional Jump                    unconditional
          JNA    Jump if Not Above                     CF=1 or ZF=1
          JNAE   Jump if Not Above or Equal            CF=1
          JNB    Jump if Not Below                     CF=0
          JNBE   Jump if Not Below or Equal            CF=0 and ZF=0
          JNC    Jump if Not Carry                     CF=0
          JNE    Jump if Not Equal                     ZF=0
          JNG    Jump if Not Greater (signed)          ZF=1 or SF != OF
          JNGE   Jump if Not Greater or Equal (signed) SF != OF
          JNL    Jump if Not Less (signed)             SF=OF
          JNLE   Jump if Not Less or Equal (signed)    ZF=0 and SF=OF
          JNO    Jump if Not Overflow (signed)         OF=0
          JNP    Jump if No Parity                     PF=0
          JNS    Jump if Not Signed (signed)           SF=0
          JNZ    Jump if Not Zero                      ZF=0
          JO     Jump if Overflow (signed)             OF=1
          JP     Jump if Parity                        PF=1
          JPE    Jump if Parity Even                   PF=1
          JPO    Jump if Parity Odd                    PF=0
          JS     Jump if Signed (signed)               SF=1
          JZ     Jump if Zero                          ZF=1
Clocks Size
Operands 808x 286 386 486 Bytes
Jx: jump 16 7+m 7+m 3 2
no jump 4 3 3 1
Jx: near-label - - 7+m 3 4
no jump - - 3 1 
        - It's a good programming practice to organize code so the
          expected case is executed without a jump since the actual
          jump takes longer to execute than falling through the test.
        - see   JCXZ  and  JMP  for their respective timings

JCXZ/JECXZ - Jump if Register (E)CX is Zero 

        Usage:  JCXZ    label
                JECXZ   label  (386+)
        Modifies flags: None

        Causes execution to branch to "label" if register CX is zero.  Uses
        unsigned comparision.

                                 Clocks                 Size
        Operands         808x  286   386   486          Bytes

        label:  jump      18   8+m   9+m    8             2
                no jump    6    4     5     5

JMP - Unconditional Jump 

        Usage:  JMP     target
        Modifies flags: None

        Unconditionally transfers control to "label".  Jumps by default
        are within -32768 to 32767 bytes from the instruction following
        the jump.  NEAR and SHORT jumps cause the IP to be updated while FAR
        jumps cause CS and IP to be updated.

                                                        Clocks
                   Operands                     808x  286    386   486

        rel8  (relative)                        15    7+m    7+m    3
        rel16 (relative)                        15    7+m    7+m    3
        rel32 (relative)                         -     -     7+m    3
        reg16 (near, register indirect)         11    7+m    7+m    5
        reg32 (near, register indirect)          -     -     7+m    5
        mem16 (near, mem indirect)             18+EA  11+m  10+m    5
        mem32 (near, mem indirect)             24+EA  15+m  10+m    5
        ptr16:16 (far, dword immed)              -     -    12+m    17
        ptr16:16 (far, PM dword immed)           -     -    27+m    19
        ptr16:16 (call gate, same priv.)         -    38+m  45+m    32
        ptr16:16 (via TSS)                       -   175+m   TS   42+TS
        ptr16:16 (via task gate)                 -   180+m   TS   43+TS
        mem16:16 (far, indirect)                 -     -    43+m    13
        mem16:16 (far, PM indirect)              -     -    31+m    18
        mem16:16 (call gate, same priv.)         -    41+m  49+m    31
        mem16:16 (via TSS)                       -   178+m  5+TS  41+TS
        mem16:16 (via task gate)                 -   183+m  5+TS  42+TS
        ptr16:32 (far, 6 byte immed)             -     -    12+m    13
        ptr16:32 (far, PM 6 byte immed)          -     -    27+m    18
        ptr16:32 (call gate, same priv.)         -     -    45+m    31
        ptr16:32 (via TSS)                       -     -     TS   42+TS
        ptr16:32 (via task state)                -     -     TS   43+TS
        m16:32 (far, address at dword)           -     -    43+m    13
        m16:32 (far, address at dword)           -     -    31+m    18
        m16:32 (call gate, same priv.)           -     -    49+m    31
        m16:32 (via TSS)                         -     -    5+TS  41+TS
        m16:32 (via task state)                  -     -    5+TS  42+TS

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