The question on the OS got me thinking.
How did OS worked on “intermediate device”. by that I mean stuff that are too advanced to be just a few logical gates and EPROM, but before the time where most electronic devices are a computer running Linux
Stuff like phone from the 00’s before android, digital camera, washing machine and other devices which were already quite advanced (Some could already run java) but not at the point to be “just an embedded computer running some hardware” Did they already had an OS ? Was it a minimalist home-made one bought to a third party ? Or was it still mostly working by counting bytes and drawing truth table ?
They used a minimal OS for embedded devices.
https://en.wikipedia.org/wiki/Embedded_operating_system
At the least, it would be something written in assembly, something like QNX, or a custom system in a language like Forth specifically for the hardware and application.