Swaps only the lower nibble (4 bits) between the Accumulator and indirect RAM. 3. Addressing Modes Summary
Since the 8051 has a limited internal RAM (128/256 bytes), it often interfaces with up to 64KB of external RAM. The MOVX instruction is specifically designed for this purpose and always involves the Accumulator ( A ). MOVX A, @DPTR or MOVX @DPTR, A Data Transfer Instructions Of 8051 Ppt
The efficiency of these instructions is governed by the addressing mode used: Data is part of the instruction ( #data ). Register: Uses R0-R7. Direct: Uses the 8-bit RAM address. Indirect: Uses @R0 or @R1 as pointers. 4. Conclusion Swaps only the lower nibble (4 bits) between
Useful for segment decoding (e.g., driving a 7-segment display). 2.4 Stack Operations ( PUSH and POP ) The MOVX instruction is specifically designed for this
Swaps the full byte between Accumulator and a register.