5 ms·

Very interesting. Does anyone have any idea how the C compiler was bootstrapped. Was it first written in B, or was it written in PDP-11 assembler?

QuantumG 6y ago
Flint knives and bear skins.
- dboreham 6y ago
  Abacus
AntiRush 6y ago
The basic sequence was: - Rewrite B compiler in B (generating threaded code) - Extend B to a language Ritchie called NB (new B). This compiler generated PDP assembly There is no version of the NB compiler known to exist. - Continue extending NB until it became the very early versions of C. You can read the longer version of this history here: https://www.bell-labs.com/usr/dmr/www/chist.html https://www.bell-labs.com/usr/dmr/www/chist.html
0x003 6y ago
I think it was written in B as Ritchie extended B for the PDP-11. By that point the B compiler was written in B https://sci-hub.do/10.1145/155360.155580 https://sci-hub.do/10.1145/155360.155580
- EGreg 6y ago
  Real programmers use butterflies
  - macksd 6y ago
    A reference to https://xkcd.com/378/ https://xkcd.com/378/, for those wondering.
retrac 6y ago
It was written in B. And B was written in B. To trace the bootstrap up into the high level, you have to go further back than the PDP-11. To bootstrap B on the PDP-7 and GE-635 machines he had access too, Ritchie wrote the minimum subset required to compile a compiler in B, in a language known as TMG (in the vein of, and a big influence on, Yacc and similar). This minimal bootstrap was then used to compile a B compiler written in B, and further development was self-hosted. Later, the language would be retargeted to the PDP-11 while on the PDP-7. Various changes, like byte-addressed rather than word-addressed memory, led to it morphing into C after it was moved. There was no clear line between B and C -- the language was self-hosting the whole time as it changed from B into C. Mr. Ritchie wrote a history from his perspective published in 1993. I've mostly just summarized it above. It's available here: https://web.archive.org/web/20150611114355/https://www.bell-labs.com/usr/dmr/www/chist.html https://web.archive.org/web/20150611114355/https://www.bell-...
- systemvoltage 6y ago
  When people say bootstrapping, is this how all computer languages came to be? Or there has been multiple attempts at bootstrapping? What I’m getting at is whether all languages have a single root.
  - retrac 6y ago
    Yes, bootstrapping with regard to languages is the trick of getting that first compiler running so you can compile the rest of the compiler. It has been done many times. The first assemblers were written directly in machine language. The first compilers were written in assembly. Many implementations of FORTRAN, ALGOL, COBOL, etc. As late as the 1970s it was not unknown to write a new high level language directly in machine code. Steve Woz's BASIC for the Apple II was "hand-assembled", as he put it. So, taken literally, certainly not. People still do it today as a hobby or educational project. But if we take the question in a looser sense? Yes kind of, at least in the UNIXish world. No one has implemented a serious high level systems language, except in a high level systems language, for a long time now. Rust, for example, was initially implemented in Ocaml. And normally that's what would be called the first Rust bootstrap. But OCaml was implemented in C, probably compiled by Clang or GCC. GCC was written in C and... so on. Often one finds it does lead back to DMR at a PDP-7. On the other hand, I strongly suspect something like IBM's COBOL compiler for their mainframes (still supported and maintained today!) would not have such a heritage.

QuantumG 6y ago

Flint knives and bear skins.

dboreham 6y ago
Abacus

AntiRush 6y ago

The basic sequence was: - Rewrite B compiler in B (generating threaded code) - Extend B to a language Ritchie called NB (new B). This compiler generated PDP assembly There is no version of the NB compiler known to exist. - Continue extending NB until it became the very early versions of C. You can read the longer version of this history here: https://www.bell-labs.com/usr/dmr/www/chist.html https://www.bell-labs.com/usr/dmr/www/chist.html

0x003 6y ago

I think it was written in B as Ritchie extended B for the PDP-11. By that point the B compiler was written in B https://sci-hub.do/10.1145/155360.155580 https://sci-hub.do/10.1145/155360.155580

EGreg 6y ago
Real programmers use butterflies
- macksd 6y ago
  A reference to https://xkcd.com/378/ https://xkcd.com/378/, for those wondering.

retrac 6y ago

It was written in B. And B was written in B. To trace the bootstrap up into the high level, you have to go further back than the PDP-11. To bootstrap B on the PDP-7 and GE-635 machines he had access too, Ritchie wrote the minimum subset required to compile a compiler in B, in a language known as TMG (in the vein of, and a big influence on, Yacc and similar). This minimal bootstrap was then used to compile a B compiler written in B, and further development was self-hosted. Later, the language would be retargeted to the PDP-11 while on the PDP-7. Various changes, like byte-addressed rather than word-addressed memory, led to it morphing into C after it was moved. There was no clear line between B and C -- the language was self-hosting the whole time as it changed from B into C. Mr. Ritchie wrote a history from his perspective published in 1993. I've mostly just summarized it above. It's available here: https://web.archive.org/web/20150611114355/https://www.bell-labs.com/usr/dmr/www/chist.html https://web.archive.org/web/20150611114355/https://www.bell-...

systemvoltage 6y ago
When people say bootstrapping, is this how all computer languages came to be? Or there has been multiple attempts at bootstrapping? What I’m getting at is whether all languages have a single root.
- retrac 6y ago
  Yes, bootstrapping with regard to languages is the trick of getting that first compiler running so you can compile the rest of the compiler. It has been done many times. The first assemblers were written directly in machine language. The first compilers were written in assembly. Many implementations of FORTRAN, ALGOL, COBOL, etc. As late as the 1970s it was not unknown to write a new high level language directly in machine code. Steve Woz's BASIC for the Apple II was "hand-assembled", as he put it. So, taken literally, certainly not. People still do it today as a hobby or educational project. But if we take the question in a looser sense? Yes kind of, at least in the UNIXish world. No one has implemented a serious high level systems language, except in a high level systems language, for a long time now. Rust, for example, was initially implemented in Ocaml. And normally that's what would be called the first Rust bootstrap. But OCaml was implemented in C, probably compiled by Clang or GCC. GCC was written in C and... so on. Often one finds it does lead back to DMR at a PDP-7. On the other hand, I strongly suspect something like IBM's COBOL compiler for their mainframes (still supported and maintained today!) would not have such a heritage.