As for your original question #1, people who have used Unix or Linux are aware of the "standard Unix date format". It was invented when computers used "word" storage rather than byte storage, with two or four bytes making up a word. Computers were fast working with words, so when the Unix founders defined a format for dates, they saw that they could fit a number of seconds in a 4-byte word that would span 136 years. So, they based their dates on seconds since the beginning of January 1, 1900. It would work until 2036 -- far into the future from 1969. A 64-bit word would've worked much better, but on computers of that day, it would have slowed things down tremendously.
Nowadays, there are faster computers and other standards for storage of dates, but that old one lives on and is the standard for Memento on Android -- and apparently not on your desktop platform. I hope Memento is free of this constraint at some point. It is archaic.
But now I have another question. Are you suggesting that you can enter a date in 1848 on the desktop and on the mobile edition, you can see it displayed correctly? If so, then can you edit it or use it in a calculation? I seriously doubt the latter, and I doubt the former, as well. As far as I know, we're just stuck with post-1900 in the mobile edition.
Android's java machine (called DVM) uses long type of variables for dates, so one could track his ancestors up to Sun, 2 Dec BC 292269055, 16:47:04 +0000
It was the moment when our forefathers first set their flippers on the dry land crawling out of the Ocean.
There was a question about the datepicker limit in StackOverflow.
Apparently the specified range is default. But it may be changed if the developer sets a range in the program's code for the datepicker.
So, one might as well raise an issue in the uservoice. It can be resolved by a one-line code.
My question was: If after that you view the entries on Android, what do you see in the Date fields?
Thanks for your help.