Sunday, February 28, 2016

8051 Indexed Addressing Mode

Indexed Addressing Mode

  • Indexed addressing mode is widely used in accessing data elements of look-up table entries located in the program ROM space of the 8051.
  • Is used when there is a need to retrieve data from a lookup table located in the program ROM
  • DPTR is used to hold base address of table and accumulator is used to hold the index
  • Sum of DPTR and Accumulator forms the effective address for JMP or MOVC instruction
  • Jump tables or look-up tables are easily created using indexed addressing
  • 8051 has 64K bytes of code space, MOVC instruction to access a portion of this 64K-byte code space as data memory space
  • Example:
  • MOV A, #08H
    MOV DPTR, #1F00H

Related topics:
8051 Addressing Modes   |   8051 Register Addressing Mode   |   8051 Direct Addressing Mode   |   8051 Indirect Addressing Mode   |   8051 Immediate Addressing Mode   |   8051 Relative Addressing Mode   |   8051 Absolute Addressing Mode   |   8051 Long Addressing Mode   |   8051 External Addressing Mode

List of topics: 8051

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