Hi Joachim,

all 8051 need no special initialization. The stack points already to a valid address.

But there are several faults on your design:

1. the two caps (22...33pF) MUST be conncted.

2. the reset vector was 0000h and not 0020h.
If you not want to start the main at 0000h, you must place a JMP to your main at 0000h.


3. what happens after "code z" ?
You must always continue after it, e.g. jump to the beginning of your main (main loop).


Peter