>Howdy!
>
>I have not actually tried to complement the C bit directly in a PIC.
>However, based on this discuession I took a careful look at the docs, and
>they seem to imply that:
>
>>        movlw   1
>>        xorlw   STATUS, F
>
>WILL NOT WORK.  I guess the simulator in MPLAB has a bug in this regard, or
>is an undocumented feature?


In "Programming and Customizing the PIC Microcontroller", I made this
mistake in one of the early experiments that show how the different
instructions change the STATUS Register.

The MS-DOS Command Line "MPSIM" that is supplied with the book will allow
the status register to be updated in this case.  The simulators available
from Microchip (and others?) are definitely spotty in this regard.  Some do
work correctly and some don't.

In the actual PICMicro hardware themselves, having the STATUS Register the
destination of an arithmetic or bitwise operation will not set the Carry,
Digit Carry or Zero Flag as you would expect.

Instead, for the sequence above, you would have to use:

  movlw  1
  xorwf  STATUS, w
  movwf  STATUS

myke

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Also look at:

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