STX        STore indeX register
Category:  Index register control
Function:  M <-- (IXH)
           M + 1 <-- (IXL)

Effects on the Condition Codes
H = N/A
I = N/A
N = IXH7
Z = (~IXH7&...&~IXH0)&(~IXL7&...&~IXL0)
V = 0
C = N/A

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

DIR     STX     M           DF      M
EXT     STX     M           FF      MH      ML
INDEX   STX     Disp,X      EF      Disp