mriendeau@vicr.com <mriendeau@vicr.com> wrote:

>   We're talking about a couple of milliseconds.  Surely that's
>   fast enough, especially considering the fact that the program's
>   out of control anyway.

A couple of milliseconds at line frequencies, involving power
devices which are switching over 800W of power is quite
significant.

>  Maybe I'm misunderstanding what you mean here, but I don't think
>  so.  If the PC is allowed to execute all the instructions in the
>  "unused" space, it'll eventually wrap around to address 0000, on
>  page 0.

Again, the issue is the time it takes to wrap-around.  The following
program is an example of the macro (Which can be assembled, and tested
with MPSIM). The maximum time till the program delivers a reset
condition is only a few instructions. Forgive the previous post
which implied the "detection of page change".  You have to manually
insert the few lines of code for the PCLATH modification to each page.


                              Regards,
                                  Mike

----------------------------------------------------------------------
 TITLE           "Reset test program"
;
;
 Processor       16C73
 Radix  HEX
 EXPAND
;
   PCLATH   equ    0x0A
;
;  Status register bits
;
   CRY      equ    0
   DCRY     equ    1
   Z        equ    2
   PD       equ    3
   TO       equ    4
   RP0      equ    5


ORG     0x00

Start:  nop
        ;
        ;
        ;*** Test Fault ****
        bsf PCLATH,3
        goto 0x900
        ;*******************
        ;
        ; your first page code goes here
        ;
        fill   (goto Start),0x800-$
        ;
        ;
        ORG    0x800
        bcf    PCLATH,3
        goto   0x00
        ;
        ; Any routines you want to add to this page go here
        ;
        fill   (goto 0x800),0x1000-$
END