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How was assembly code written and inputted in early CPUs?

Hi guys

I can't seem to find the answer to this, how did programmers in the early days write and store assembly code.

Did they have keyboards yet? How were the text files saved? I don't really get how you can type assembly code and save it (and then load it) when there's no software for the CPU yet.
gpt
the very earliest ones had toggle switches, i think. there was no assembler and you directly input machine code. later they had paper card readers which loaded the program into memory. tape was typically used for longer term storage. disk drives have been around for a long time too. there was also core memory which was a non-volatile ram. i forget what came before core. they also had drum memory which i was sort of analogous to a disk drive iirc.