Question: Was the book from the screenshots composed in Japanese, or composed in English and then translated into Japanese?
Since it's apparently from Fujitsu, I could see it being the former, but if so, I'm impressed with the quality of the English in the printf statements and code comments from non-native English speakers.
The engineers who wrote the High C compiler must have been able to read and write english well enough to have read documentation and source code for existing compilers, and I would imagine that this book was written by the creators of the language.
Since it's apparently from Fujitsu, I could see it being the former, but if so, I'm impressed with the quality of the English in the printf statements and code comments from non-native English speakers.