Hi Daniel.

All the code of the three routines is about 1000 lines.

I post a basic schematic of the code.The low priority interrupt is this one of the Timer 1.The high-priority interrupts are the external 0 and the Timer 0.

The three interrupts code are like this one:


int_timer0:
push psw
push acc
push b
push dph
push dpl
push 00h
push 01h
push 02h
push 03h
push 04h
push 05h
push 06h
push 07h

{ internal instructions }

pop 07h
pop 06h
pop 05h
pop 04h
pop 03h
pop 02h
pop 01h
pop 00h
pop dpl
pop dph
pop b
pop acc
pop psw
reti

I think the push&pop sequence is correct, but occasionally , the timer 1 (low priority interrupt) results are wrong (it's the scanning of a keyboard and it detects wrong keys).But if I use the register bank 1 in this interruption and the other ones in the bank 0, that works good!!!!I don't understand it and i don't find the mistake.
Thanks all of you for your help.