Why do we use R0 and R1 in indirect addressing mode of 8051? This question has been answered in one of the threads but i want to know how come 8051 can only select one bit for R0 or R1 and R2 to R7 is not possible. sorry if i sound a little stupid. i am a newbee in 8051
Look at the instruction encoding for the instructions that specify indirect addressing.
You'll see that only one bit is available for specifying the register to be used.
It is difficult to get a selection of more than two registers when only one bit is available for that specification.
The 8051 has, as far as I'm aware, never been described as being orthogonal.