Also it uses registers without switching banks.

displayISR: mov a,#0ffh
movx @dptr,a
mov r3,#0ffh
...

is hardly addressing r3 by its address


What is the difference between using R0-R7 in different banks by changing the current bank in the PSW and using all the 32 Registers using direct addressing ... I feel its only a matter of convenience when it comes to "how to address the first 32 registers".

If you look through the instruction set etc, you will se that most instructions are one byte and one cycle less for registers than for direct.

If you do not swictch stack/save registers, you lose the IDAT memory (080h-0ffh) which can only be address by @Ri

Erik




Erik