>> Это продолжение жизни древнего компилятора (более древнего, чем GCC).
> Ходили слухи, что GCC - форк PCC

Сам RMS утверждает что это совсем не так. Дословно "I concluded I would have to write a new compiler from scratch. That new compiler is now known as GCC".

> Hoping to avoid the need to write the whole compiler myself, I obtained the

source code for the Pastel compiler, which was a multi-platform compiler
developed at Lawrence Livermore Lab. It supported, and was written in,
an extended version of Pascal, designed to be a system-programming
language. I added a C front end, and began porting it to the Motorola
68000 computer. But I had to give that up when I discovered that the
compiler needed many megabytes of stack space, and the available 68000
Unix system would only allow 64k.

> I then realized that the Pastel compiler functioned by parsing the entire

input file into a syntax tree, converting the whole syntax tree into a chain
of "instructions", and then generating the whole output file, without ever
freeing any storage. At this point, I concluded I would have to write a new
compiler from scratch. That new compiler is now known as GCC; none of the
Pastel compiler is used in it, but I managed to adapt and use the C front
end that I had written.

Процитировано с википедии