Question

How many special function registers are there in 8051 microcontroller?

• A. 10
• B. 20
• C. 30
• D. 40

Hint:

In 8051, all control and status operations are handled by 20 special function registers located in the upper RAM address range (80H to FFH).

Answer 1

The Correct Option is B

The 8051 microcontroller includes several Special Function Registers (SFRs) used to control the operation of the processor and peripherals.
These SFRs are located in the address range from 80H to FFH in internal RAM and include registers such as:
- Accumulator (A),
- B Register,
- Program Status Word (PSW),
- Stack Pointer (SP),
- Data Pointer (DPTR),
- Timer registers (TCON, TMOD, TL0, TH0, TL1, TH1),
- Serial communication (SCON, SBUF),
- Interrupt registers (IE, IP),
- Port registers (P0, P1, P2, P3),
Totaling exactly 20 SFRs.