> >  I did some sim-debugging and had to find out, that RETLW 
> is not restoring PCLATH correctly after returning from the 
> computed goto.
> > A normal RETURN does :-(
> >
> >   
> You are wrong. The datalist is not so clear but the PCLATH is 
> <B>NEVER</B> restored by a return.
> If you want to call a subroutine in another page:
>         PAGESEL    MySub               ;PAGESEL is an internal MPASM 
> macro that load the correct value
>         call      MySub
>         PAGESEL   CurrentPage           ;the choice of CurrentPage is 
> important!

I was not sure, if a RETURN restores the PCLATH, but all the doc's I
found in the web said, it does.
I made a small sample code for a 16F877A, jumping between the pages all
over the 8Kbyte ROM.
I used the ICD2 on real hardware with MPLAB7.50 and also the Software
Simulator in 7.50.

And ... after the RETURN, the PCLATH was restored to the value, the CALL
was made from ...
But only with a RETURN. RETLW was not restoring, but RETLW is the one to
use for tables ...

And, the datasheet is absolute clear about the PC stack:

This is from the 16F877A datasheet:

2.3.2 STACK
The PIC16F87XA family has an 8-level deep x 13-bit
wide hardware stack. The stack space is not part of
either program or data space and the stack pointer is not
readable or writable. The PC is PUSHed onto the stack
when a CALL instruction is executed, or an interrupt
causes a branch. The stack is POP'ed in the event of a
RETURN, RETLW or a RETFIE instruction execution.
PCLATH is not affected by a PUSH or POP operation. 

That means, that a RETURN, RETLW and RETFIE will cause a POP of PC (=
PCLATH and PCL) back to where the CALL was made from, or?

Best Jens

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