How were instructions given to CPU of computer before invention of disc operating system was invented?
In the 60s and 70s, the minicomputer era, the program was loaded from some other media, typically punched tape or cards. The punched tape was very commonly part of a teleprinter, but there were also high speed punches and readers. The initial program to read the tape may have been loaded by hand, by keying the instructions into the machine with a row of switches. This is typically a very short program, maybe less than 20 instructions. These instructions were stored in memory, and then once the tape was positioned, the run or execute switch was given. The program on tape may start at a different offset/address, so a second command could be given to execute that, often by the program itself once loaded. Some programs or data were also stored on various kinds of magnetic tape. Some computers had a built in “bootstrap loader” which was stored in a fixed form of ROM memory like a diode matrix etc, as this was generally the time before EPROM. There were some ROMS around, typically factory pr
