What does M1 in the upper left corner of my display mean?

SOURCE: m1 and m2 are in top left corner. How to undo it?

Press 0 [STO] 1 to clear the Memory M1. Indicator M1 will disappear.
Press 0 [STO] 2 to clear the Memory M2. Indicator M2 will disappear.

SOURCE: TI 84 plus calculator, flashing dot in upper left hand corner

Hello,

When you turn the calculator on, its screen is cleared, save for a small square on the top left corner. This is the cursor and it is blinking: The calculator is waiting for you to order it to perform some calculation.

Try this simple operation
[1] [+] [1] [ENTER]. The calculator will display the result one line down justified to the right.

Hope it helps.