Christian Kleiber wrote:
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8051: bit addressable, 12 clocks for instruction, stack pointer increments, CISC, 1 DPTR

Not true !

- different 8051 derivates exist with 1, 2, 4, 6 or 12 crystal clocks per NOP
If I remember right, also some derivates have an internal PLL and then a NOP need below 1 crystal clock.

- there are nine data pointers (@DPTR and @R0, @R1 of the 4 register banks) and two code pointers (@A+DPTR and @A+PC)


E.g. I use often @R0 and @R1 of bank 1 exclusively for the UART interrupt and @A+PC to convert the 7 segment code for the display multiplex interrupt.
It saves an impressive amount of code space.


Peter