What operating syetem does the original grey playstation use?

Sooo guys I found the PlayStation has some type of operating system.
Theirs this disc menu so if you don't insert a disc It goes into some media player thing and I wonder if its also a music player too.

 

It is embedded firmware I am pretty sure. Yes, the PS1 can play music CDs. I used to do that actually.

 

ok but what is the operating systems name?

 

The PS1 does not have an OS. It literally boots the game, kind of like how old console worked.

 

Ok but I have questions, what does phones like lg cellphones and Kyocera phones and Motorola flip phones run and how can I find what os they run. I AM NOT TALKING ABOUT SMARTPHONES IM TALKING ABOUT PHONES THAT can sorta surf the web but also phones like this
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I meant to take a picture but it went into video mode