Calendar freeze

Cause
A freeze at startup on the shown screen (with no cyclic reset) is caused by the RTC not outputing a time pulse at all.

The system ROM doesn't give a CALENDAR ERROR in this particular case because of a programming oversight.

Suggestions

 * Check battery voltage
 * Check 32768Hz crystal
 * Check traces, especially power and pin 11
 * Check interface pins
 * Check and traces to
 * Try to reset Backup RAM content:
 * Either remove battery
 * Or flip all dip switches to on and then power on the board. Then turn off the board and return all dips to normal settings
 * You can use unibios to skip this error