The Prog8 source code includes a general-purpose date manipulation library, which stores the date as a 16-bit integer counting days from the turn of the millennium, giving a range from 1911-04-15 to 2090-09-17. It also includes some TUI utilities, including the date-picker widget seen below, which only works within the years completely contained in that range (1912-2089).
The target date for the plot is chosen the same way, but defaults to the current date according to the X16's on-board real-time clock.
Once the chart is drawn you can scroll to different dates with the cursor keys, go back to the datepicker to jump around, or go all the way back and pick a new person/birthdate to calculate for.
Try It Now!
#R47
