Thanks everyone for the suggestions, will try them as soon as I get time!

GRAHAM

        ----------
        From:  Dr. Imre Bartfai [SMTP:root@PROF.PMMF.HU]
        Sent:  18 November 1999 09:49
        To:  PICLIST@MITVMA.MIT.EDU
        Subject:  Re: 12c508 problems

        Hi,
        two additional remarks:

        the 1st line is bogus even if you want to set OSCCAL manually, as
the
        statement

                movfw   0x1ff

        makes no sense.

        > >        movlw   .100            ;  Rtcc = 225

        It will load decimal 100 to W instead of 225 or whatever you
intended.

        I hope this helps.

        Regards,

        Imre


        On Wed, 17 Nov 1999, J Nagy wrote:

        > Graham North wrote:
        >
        > >I am have problems with a simple program to make leds flash with
a 508.  The
        > >program simulates correctly, but when programmed the chip does
nothing.
        > >
        >
        > Offhand, ignoring syntax that I'm not familiar with, I can see two
things
        > that I'd look at:
        >
        > >        org     0x00            ;Start of code space
        >
        > >;************************** Main ********************************
        > >
        > >        movfw   0x1ff
        > >        movwf   OSCCAL          ;Set oscillator calibration reg.
        >
        >
        > Microchip has been kind enough to place a MOVLW <osccal const> at
location
        > $1FF, the startup vector, for you. When the chip reaches location
$000, all
        > you need to do is MOVWF OSCCAL (if you intend to use the internal
        > oscillator). Eliminate your first line.
        >
        >
        > >Wait_5ms                        ;do
        > >        movwf   RTCC
        > >Timer_check                     ;do
        > >        movf    RTCC,W          ;  read Rtcc
        > >        btfss   STATUS,Z
        > >        goto    Timer_check     ;while (Rtcc<>0)
        > >        return
        >
        >
        > You've defined RTCC as register 8, but don't do anything with it
for it to
        > ever become zero. Were you perhaps thinking of register 1 (TMR0)?
        >
        > Hope this has been helpful,
        >
        >
        >         Jim Nagy
        >         Elm Electronics
        >   ICs for Experimenters
        > http://www.elmelectronics.com/
        >
        >