If it truly has no operating system, you need to write a program to make it do whatever you want it to do. Even executing a program can be a challenge without an operating system.
One of the first computers I worked with required that you enter the program using front panel switches. Each instruction on that computer was 12 bits, so you set the 12 switches, and pressed an "enter" switch. It took a couple of minutes to enter enough instructions to make it read a program from punched paper tape. The paper tape program would then do something useful. To change programs, you repeated the process from the top.
Later, I worked on a more "modern" computer that used magnetic tape instead of paper tape, but the process was very similar. The first program it read was an operating system that allowed files to be read from or written to the magnetic tape, and allowed operator interaction using a teletype.
Some simple electronic devices with processors built in, a microwave oven or washing machine, for example, may not have a recognizable operating system. Of course, it has some sort of software to manage the available resources (lights, buttons, valves, whatever), but the sort of management that Windows or Mac OS X might do is not usually required.
The operating system is a convenience for human operators and for programs. It also can allow the computer to "multitask" so that it appears to be working on several things at once without those things interfering with each other. Without it, you don't necessarily have that convenience.
One of the first computers I worked with required that you enter the program using front panel switches. Each instruction on that computer was 12 bits, so you set the 12 switches, and pressed an "enter" switch. It took a couple of minutes to enter enough instructions to make it read a program from punched paper tape. The paper tape program would then do something useful. To change programs, you repeated the process from the top.
Later, I worked on a more "modern" computer that used magnetic tape instead of paper tape, but the process was very similar. The first program it read was an operating system that allowed files to be read from or written to the magnetic tape, and allowed operator interaction using a teletype.
Some simple electronic devices with processors built in, a microwave oven or washing machine, for example, may not have a recognizable operating system. Of course, it has some sort of software to manage the available resources (lights, buttons, valves, whatever), but the sort of management that Windows or Mac OS X might do is not usually required.
The operating system is a convenience for human operators and for programs. It also can allow the computer to "multitask" so that it appears to be working on several things at once without those things interfering with each other. Without it, you don't necessarily have that convenience.