With no documentation and no other means of contacting the developer for guidance, I was forced to initially post a negative review in the hopes of getting some feedback as to how some of the features were supposed to work. After reading the developer’s subsequent feedback, I at least now know what the “diskette” and “folder” icons are supposed to do (see developer’s response — spoiler alert: tapping the “folder” icon will create an archive of all of the calculations that were on the screen, and the blank input screen you see is simply for entering the title you want to give that archive.) So, all in all, except for a few quirks (eg. adding a title to an individual calculation inserts it below the calculation instead of above?), it really is a pretty useful calculator. Now, if only there was a way to paste in values or expressions, or go back and edit a calculation you previously entered, that would be really helpful.
The instructions and examples: Save: Tap on the “diskette” icon to save current history data which is displayed on the screen, type a title in the title box for the data. Load: You can tap on the “folder” icon and then choose a line with its title(The format: Your title + [rows of the data]) which you saved to bring the history data back to your screen. If you have further questions about this, you can also send an email to contact us (yytechplayer@qq.com).--For example, A.Enter:1+2+3=6,1+100=101,1+1+1+1=4.B.Tap on the “diskette” icon to save the three rows of data on the screen, give it a title "my test data A".C.Clear the screen.D.Enter:2+1=3,2+22=24.E.Tap on the “diskette” icon to save the two rows of data on the screen, give it a title "my test data B".F.Tap on the “folder” icon and then choose a line with title "my test data A" and you can see the three rows of history data displayed on the screen instead of that two rows of data.G.Tap on the “folder” icon and then choose a line with title "my test data B" and you can see the two rows of history data displayed on the screen instead of that three rows of data.