By: Masud-ul-Hasan
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SFRs (Special Function registers)
•B Register: (at F0H) also bit addressable and used along with the accumulator for multiply & divide operations.
E.g., MUL A B instruction multiplies the 8-bit unsigned values in A & B and leaves the 16-bit result in A (low-byte) & B (high-byte)
E.g., DIV A B instruction divides A by B leaving the integer result in A and remainder in B.
•SP: (Stack Pointer) (at 81H) is an 8-bit register contains the address of the data item currently on the top of stack. Its operations include “Pushing” & “Popping” data from the stack.
•DPTR: (Data Pointer) is 16-bit register at 82H (DPL, low-byte) and 83H (DPH, high-byte) used to access external code or data memory. It can be specified by its 16-bit name, DPTR, or by each individual byte name, DPH and DPL.
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