You cannot enter fractional values in programmer mode.

This is reasonable, but what is incredibly annoying is that when you type in a number while in Programmer mode, if you then change to Scientific mode, it blows away the number you typed in.

Programmer mode is useful if you need to convert Decimal/Hex/Binary, but if you try to enter e.g, 17.95 as a decimal number, you can't. (In fact, it'll display 17 NAND 95 - so the dot seems to be a shortcut for a bitwise operation) - it's Integers Only.

(I guess one could argue that programmer mode should include IEEE-754 floats, but I'm fine with that mode being limited to integers, it's plenty useful already. But it does require switching to another mode if you need a calculator to calculate floating point numbers)