4 ms·

OK, how about this: C was the first portable, non-assembly language used for writing OS kernels. Is that true? And I mean portable in practice, not just in theo

by cbd1984 12y ago

OK, how about this: C was the first portable, non-assembly language used for writing OS kernels. Is that true? And I mean portable in practice, not just in theory, and portable beyond one family of computers.

pjmlp 12y ago
No. OS were already being written in BCPL, Algol, Algol W, Algol 68, PL/I, PL/M and many other languages, battling for a place in the podium of systems programming languages. C was tied to UNIX, just as the others were tied to the OS of their vendor. C only became portable after UNIX was available in a few American universities outside AT&T, some students decided to create workstations based on UNIX, while others started to develop C compilers, so that they could continue their work on other systems.
- meowface 12y ago
  Didn't BCPL and Algol heavily influence C though? What features of BCPL or Algol or other, older languages that were ignored could have made C better?
  - pjmlp 12y ago
    BCPL not much. It was barely an high level assembler. Now Algol, it had: - Bounds checked arrays - Reference parameters to functions/procedures - Real strings (not the first version in 1960 though) - Explicit conversions Quote from Tony Hoare's ACM award article[1]: "A consequence of this principle is that every occurrence of every subscript of every subscripted variable was on every occasion checked at run time against both the upper and the lower declared bounds of the array. Many years later we asked our customers whether they wished us to provide an option to switch off these checks in the interests of efficiency on production runs. Unanimously, they urged us not to--they already knew how frequently subscript errors occur on production runs where failure to detect them could be disastrous. I note with fear and horror that even in 1980 language designers and users have not learned this lesson. In any respectable branch of engineering, failure to observe such elementary precautions would have long been against the law." [1]http://www.labouseur.com/projects/codeReckon/papers/The-Emperors-Old-Clothes.pdf http://www.labouseur.com/projects/codeReckon/papers/The-Empe...
vidarh 12y ago
Multics was mostly written in PL/I. PL/I is certainly portable, though I don't think Multics itself was particularly portable. BCPL was used to write several OS's that were ported, though while BCPL predates C, I'm not sure if any of the OS's written using it predates Unix.

by cbd1984 12y ago

pjmlp 12y ago

No. OS were already being written in BCPL, Algol, Algol W, Algol 68, PL/I, PL/M and many other languages, battling for a place in the podium of systems programming languages. C was tied to UNIX, just as the others were tied to the OS of their vendor. C only became portable after UNIX was available in a few American universities outside AT&T, some students decided to create workstations based on UNIX, while others started to develop C compilers, so that they could continue their work on other systems.

meowface 12y ago
Didn't BCPL and Algol heavily influence C though? What features of BCPL or Algol or other, older languages that were ignored could have made C better?
- pjmlp 12y ago
  BCPL not much. It was barely an high level assembler. Now Algol, it had: - Bounds checked arrays - Reference parameters to functions/procedures - Real strings (not the first version in 1960 though) - Explicit conversions Quote from Tony Hoare's ACM award article[1]: "A consequence of this principle is that every occurrence of every subscript of every subscripted variable was on every occasion checked at run time against both the upper and the lower declared bounds of the array. Many years later we asked our customers whether they wished us to provide an option to switch off these checks in the interests of efficiency on production runs. Unanimously, they urged us not to--they already knew how frequently subscript errors occur on production runs where failure to detect them could be disastrous. I note with fear and horror that even in 1980 language designers and users have not learned this lesson. In any respectable branch of engineering, failure to observe such elementary precautions would have long been against the law." [1]http://www.labouseur.com/projects/codeReckon/papers/The-Emperors-Old-Clothes.pdf http://www.labouseur.com/projects/codeReckon/papers/The-Empe...

vidarh 12y ago

Multics was mostly written in PL/I. PL/I is certainly portable, though I don't think Multics itself was particularly portable. BCPL was used to write several OS's that were ported, though while BCPL predates C, I'm not sure if any of the OS's written using it predates Unix.