There are many claims that I think are incorrect, misleading or unrelated.
> According to Glenn, it is very hard to figure out what TeX code is doing, mostly due to its terseness and extreme optimization, as outlined above
The TeX source code is in literate programming, so it's not "terse" in the standard sense.
> there was no IEEE standard for floating point arithmetics;
I always suppose that the integer arithmetic was to ensure 100% portability. Every system handles integer equally (if you avoid undefined behavior), but there are lot of small incompatibilities with the floating point numbers (for example, single, double or extended precision).
> portability meant supporting almost 40 different OSes, each of them with different file system structures, different path syntax, different I/O and allocation APIs, character sets;
The original version of TeX was ASCII only, and using other character sets is always a problem. (For example, in LaTeX you must use a package like inputenc.)
I would be curious to know if the woven sources were used over the tangled ones. As probably the only program I own in printed form, the source is much more readable than I would have ever thought possible.
> According to Glenn, it is very hard to figure out what TeX code is doing, mostly due to its terseness and extreme optimization, as outlined above
The TeX source code is in literate programming, so it's not "terse" in the standard sense.
> there was no IEEE standard for floating point arithmetics;
I always suppose that the integer arithmetic was to ensure 100% portability. Every system handles integer equally (if you avoid undefined behavior), but there are lot of small incompatibilities with the floating point numbers (for example, single, double or extended precision).
> portability meant supporting almost 40 different OSes, each of them with different file system structures, different path syntax, different I/O and allocation APIs, character sets;
The original version of TeX was ASCII only, and using other character sets is always a problem. (For example, in LaTeX you must use a package like inputenc.)