>Just a quick update, I pulled the crystal and installed an RC oscillator.
>Now the PIC works. So it must have to do with the config register and/or the
>programmer. Any help?

Assuming you're using PICSTART Plus or MPLAB-ICD, you'll find a
pull-down that selects between RC and other choices. That needs to be
correct when you program your device.

Most C compilers have a special configuration directive like

__CONFIG( RC )

that, when compiled, results in the hex code (*.hex) containing the
settings required for the configuration word.  MPASM has a similar
directive.

BTW, the config word is just another programmable address, but it's
way up high in memory. When you set it manually (when programming) or
automatically (via CONFIG directives in C or assembly) , you're
simply programming that address with device-specific configuration
settings.

When you assemble or compile an application, the manual settings in
PICSTART Plus or MPLAB-ICD reflect the value of the config bits, i.e.
they "read" the hex file. So if you do nothing, the oscillator bits
will remain at 1 (unprogrammed PIC).  On the 16C77 (and many others),
1's in FOSC1:FOSC0 mean "RC oscillator is selected." So that's why it
works with RC and not HS or XT.

Regards,
--

  ______________________________________
   Andrew E. Kalman, Ph.D.   aek@pumpkininc.com

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