When I started using computers, the Disk Operating System (DOS) was required to be read from a 360K 5.25" floppy in order to boot, otherwise the EEPROM made the monochrome monitor show [A:\> no operating system found_]. Then, if you wanted to start a word processing program, the OS) having been loaded into RAM, you had to remove the OS diskette and insert the word processor diskette, and at the A:\> prompt enter the command (*.exe filename) at that prompt to get the program to run. Then you would type your paper, letter or whatever (and it had the capabilities of an IBM Selectric III Typewriter) and save it, yes, to a different 360KB diskette. So, you had to hace an OS floppy, a Program floppy, and a File floppy. I originally typed this post using C:\ as the A: drive--it has been that long. You were king if you had 2 floppy drives back then, an A: and a B:. If you started by putting the OS in drive A: and a program in drive B: then you might see the following screen:
A:>_
A:>b:\zork.exe_
and ZorkI would start
dang I'm old; fudge I'm a geek.