CALENDAR_DOT_EXE is a 1,999,998 year calendar that can display a calendar for years -999,999 to +999,999 for the Gregorian, Julian, and Jewish calendars.
I wrote a blog post titled "CALENDAR_DOT_EXE - Added Jewish Calendar Support" that goes into more details about this project.
CALENDAR_DOT_EXE - Added Jewish Calendar Support
Download the NES ROM
NES ROM File