The only exception I can think of is early versions of mac os, which was still primarily assembly. Even then i recall people went out of their way to use C despite needing pascal calling convention for system calls. They basically immediately regretted using pascal and started a march towards C and basically gave up on pascal before the powerpc.

So Pascal had one mainstream OS for about 10 years, most of which time it was being phased out.

> which os was written in Pascal? most were written in assembly in that era, you are talking about some obscure research or toy.

Your first claim: Every OS was written in C. Your new claim: Most were written in assembly.

Pick a position. If most were written in assembly then it would not have had any impact on the adoption of Ada so why make the original claim?

I would respond to your question but you substantially edited your comment and removed the question. I also notice you removed the claim in your edit about most OSes being written in assembly in the 80s. Obnoxious way to communicate with people, altering your comments while they're replying so their replies look like random comments.

> They basically immediately regretted using pascal and started a march towards C and basically gave up on pascal before the powerpc.

Nonsense. MPW Pascal and Think Pascal were well supported developer tools, and a lot of third-party developer code was written in them during the 80's. Photoshop (1987) was originally written in Pascal! Apple's Pascal dialect had object extensions that made OOP simpler than with C or standard Pascal.

Pascal started to leave the building circa 1991, when C++ became viable for OOP. Even then, Metrowerks CodeWarrior supported native Pascal compilation for PowerPC in 1993/4.