Maxim Integrated High-Speed Microcontroller Users Guide: DS80C390 Supplement - Manual (Page 117)

High-Speed Microcontroller User’s Guide: DS80C390 Supplement
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software tools (assembler or compiler) specifically designed to accept the modified length of the new
instructions.
In addition, the 22-bit contiguous mode utilizes the MXAX register to supply the upper 8-bits of the 22-
bit (or 23-bit if CMA=1 or IDM1=) address bits of the MOVX address during register indirect MOVX
instructions such as MOVX @Ri, A or MOVX A, @Ri. The complete address is formed by
concatenating MXAX, P2, and R1 or R0 in this mode. The DPTR-related MOVX instructions do not
utilize the P2 and MXAX register.
The instructions modified to operate in the 24-bit address mode are summarized in the following table.