And what would do that “read data off disk, then write other data back”, if not a program? Even if you use a monitor (https://en.wikipedia.org/wiki/Machine_code_monitor) to write a program, that’s still a program.
The only way to avoid that is to hand-punch a tape or something like that (with lots of practice and patience, it may be possible to program a small PROM or write an early floppy by hand)
I've compiled some simple C (microcontroller blinky) by hand. Then assembled and linked the output, and written the machine code into a HEX (Intel format) file. Then tested it on the micro. It's a rather fun exercise (Type 2 fun).
Fun with extra twists and turns you weren't expecting. Usually quite an adventure, some unintended learning and growth. Hopefully a story worth telling.
As opposed to the obvious doing an activity for fun.
The only way to avoid that is to hand-punch a tape or something like that (with lots of practice and patience, it may be possible to program a small PROM or write an early floppy by hand)