[strategarius]

As noticed above, creators admitted that creating OS written in Assembly was a challenge for them. However, I totally agree about optimizing capabilities of modern compilers. Interesting fact on the topic, my friend, Principal Developer of well-known tech giant has a practice of picking up candidates, who mentioned "fluent Assembly" skill in their CV, and challenge them by suggesting to create a small, highly optimized application. After that he compiles the same application in C++ with maximum optimization, and in 90% of cases generated code is more optimal, that written manually. However, before becoming all sceptical about obsolete skills of learning Assembly, I would point out on the rest 10% of his candidates.

[z3phyr]

Do they mention fluent x86-64 or arm assembly? Because there are many ISAs where no C++ compiler will be able to generate better code than hand optimal code by a fluent programmer.

[fluffything]

Exactly, when the only compiler available for an ISA is gcc 2.9... manually writing the assembly doesn't sound that bad anymore. C++11? There isn't even a C++03 compiler for those..

[strategarius]

I think, sinse he's working on internet search and knows targer architecture in advance, he meant x86_64 assembly, used probably for platform-specific fine-tuning