8051 memory spaces overview Is it correct that the 8051 architecture divides address space into four distinct areas: internal data, external data, internal code, and external code?

Difficulty: Easy

Correct Answer: True

Explanation:


Introduction / Context:
Classic 8051 devices use a Harvard-like separation of program and data spaces, and further distinguish on-chip versus off-chip regions. Understanding these four areas is fundamental for correct instruction selection (MOV vs MOVX) and linker configuration.


Given Data / Assumptions:

  • Internal data (IRAM/SFR) vs external data (XDATA).
  • Internal code (on-chip ROM/Flash) vs external code (off-chip program memory).
  • EA pin influences code fetch source.


Concept / Approach:
The 8051 maps internal data (lower RAM, bit-addressable, SFRs) separately from external data accessed via MOVX. Program memory is fetched from an internal array when present or from external memory via PSEN when configured, hence four distinct categories.


Step-by-Step Solution:

1) Internal data: 0x00–0x7F RAM, bit area, SFRs (0x80–0xFF).2) External data: accessed with MOVX via DPTR/@Ri.3) Internal code: on-chip program store when EA = 1.4) External code: off-chip program store when EA = 0 or beyond on-chip range.


Verification / Alternative check:
Any 8051 memory map confirms these four distinct spaces.


Why Other Options Are Wrong:
False would contradict standard 8051 architecture.


Common Pitfalls:
Attempting to use MOV for external data, or confusing SFR region with general RAM.


Final Answer:
True

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