8051 SFR naming vs addressing The special function registers of the 8051 can be referred to by their hexadecimal addresses or by their symbolic register names. Choose the correct statement.

Introduction / Context:
Special Function Registers, or SFRs, implement core control and status features of the 8051 microcontroller, such as port latches, timer registers, serial control, and the accumulator. Toolchains generally allow programmers to access these registers either by their absolute addresses or by standardized symbolic names. This question validates understanding of how SFRs are referenced in assembly and C toolchains for 8051.

Given Data / Assumptions:

• Device family is classic 8051 and compatible derivatives.
• Assembler supports standard SFR symbols like ACC, B, PSW, P0, P1, TMOD, TH0, etc.
• All SFRs reside in the upper data space 80H to FFH and are byte addressable.

Concept / Approach:

In assembly, programmers may write either a name (for example, MOV A, P1) or an explicit address (for example, MOV A, 90H) to refer to the same SFR. In C, header files typically map names to addresses via definitions so code can remain readable and portable.

Step-by-Step Solution:

Verification / Alternative check:

Consult any standard 8051 assembler manual or device header: it shows SFR address tables paired with names. Assembling small test code with both forms yields identical opcodes.

Why Other Options Are Wrong:

False: denies a widely supported feature.

Only by hexadecimal addresses: reduces readability and contradicts standard practice.

Only by register names: ignores that low level code can still refer to raw addresses.

Common Pitfalls:

Confusing bit-addressable SFR bits with byte-wide SFR addresses, and forgetting that not all SFRs are bit-addressable.

Final Answer:

True