Websites, mobile apps, desktop apps and mobile OSes are developed and updated using the desktop OSes, which I would call the 'master OS'. But who updates the 'master'? How do the devs upgrade Windows 10 to Windows 11 using Windows 10?
I have some experience in computing but software development for operating systems is completely mysterious for me. I have had this question ever since I learned about software development in general.
I saw Apple say how they use the Macs to build all of their other products and softwares, but they never answer how they build macOS itself. I understand how these companies could design an upgraded or a brand new computer by designing its new architecture as well as the circuitry and the components underneath with the help of a program like CAD. What I don't understand is how they upgrade their existing software they themselves work in, especially when it has completely new features the old one doesn't have. I feel like this is similar to a person performing a brain surgery on himself.
I would really appreciate if someone could ELI5 but only dumb it down enough for a person that understands how to really work with computers and knows the general theory of programming , like an amateur or the family IT guy.
While I'm not experienced enough to explain the full development stack of an OS. Let me throw my two cents.
It typically goes by writing changes. If its superficial ones, like modern UI in Windows 11, then all they need to do is relaunch explorer/the app etc. Every time they make a change in the code, they then build and try it out.
If its a more internal change, deep into the OS. Typically written in C or another low level language. Then its easier to test the changes in a virtual machine, you write your code, compile, build. And then load it up in the virtual machine to see if the OS doesn't crash and burn.
Later, after it gets past quality control in the company, (but most often these versions sit in beta for a while to catch problems). It then gets put into the Update servers and rolled out in bulk for mass destribution.
Do note, updates don't need to include the entire OS. Just packages including the file changes as well as general update busywork.
PS: If anyone replies, feel free to correct me. Details may be sketchy but this is the short of it.