SUBD       Double SUBtract without carry
Category:  Arithmetic operation
Function:  ACCAB <-- (ACCAB) - (M:M + 1)

Effects on the Condition Codes
H = N/A
I = N/A
N = R15
Z = ~R15&~R14&~R13&...&~R0
V = AB7&~M15&~R15|~AB15&M15&R15
C = ~AB15&M15|M15&R15|R15&~AB15

ADDR    MNEM    OPER        1st     2nd     3rd
MODE    ONIC    FRMT        BYTE    BYTE    BYTE
________________________________________________

IMM     SUBD    #Imm        83      ImmH    ImmL
DIR     SUBD    M           93      M
EXT     SUBD    M           B3      MH      ML
INDEX   SUBD    Disp,X      A3      Disp