So, I'm soon going to be in a place where I don't have access to a computer, but where I'm hoping to sharpen my assembly skills. Is there any program or operating system that allows one to program assembly code directly onto the calculator, without writing it on a computer first? If not, is there some method to manually program assembly into the calculator? Thank you in advance!

I'm not entirely sure, but I think its possible to write all HEX codes and then run it as an assembly program. But I don't know how extensive hex is, or how much you could possibly learn/know.

If you're referring to the monochrome 83+/84+, Mimas is an excellent on-calc assembler. If you're referring to the 84+CSE or 84+CE, you're out of luck (you could technically write machine code, but I highly advise against this).

EDIT: It appears that Runer posted first

It depends whether you have a color calculator or not. If you have a 83+ or 84+ you can, with another ASM program. You can try Mimas.

Yes, you can theoretically write asm all in hex. It is the same as compiling it, so it is just as extensive as the more common methods of writing asm however, unless you spent a bunch of time memorizing some hex equivalents, odds are you won't be able to actually write anything slightly extensive directly in HEX (although it's 100% doable) so essentially, for color calcs you're out of luck.

Thank you Runer112 for answering on both forums . Sorry for reposting it on Omnimaga, I just wasn't sure how active these forums were.
Thank you also mr. womp womp and Domino464 for the useful information!

I originally joined Cemetech to gather info on how to make an in-calc ASM editor, but due to a rise in popularity for the CE, I decided to wait until I could catch the CE in my hands (not happening any time soon).

Besides, chances are very high that you'll crash the calculator running your program. Sure, your broken program will be saved, but how could you know where you messed up, or how could you not have to waste 15 seconds of your life restarting the calculator and opening the editor again every time you mess up? You couldn't. The Z80 doesn't have exception handling or any sort of protection on the hardware level; it just crashes smack into the wall, corrupting the memory. Without a rather complex wrapper to check for memory access faults, an in-calculator ASM editor would not be very intuitive.

There's Axe and Mimas/ASMDREAM for the B/W 83+ series calcs. Crashes just reset your RAM, so as long as your source code is in archive (which it probably will need to be anyway if you're writing anything substantial since programs need to be run from RAM and your source is gonna take up a lot more space than your program) i don't see why an on-calc assembler wouldn't work. It's just a lot slower to type and not as convenient/organized as writing on a computer.