[TUHS] "Notes on the IBM C Compiler" by Mike Lesk

[Clem Cole via TUHS]

BLISS was CMU's system programming language, designed by Bill Wulf and his
students in the late 1960s/early 1970s. The original compiler was a PDP-10
target (the urban legend is that it was bootstrapped using TECO macros, but
I don't believe that).  BLISS-11 followed a few years later; it was a
cross-compiler that ran on TOPS-10 (it could not self-host).  Compared to
Dennis's C compiler, a contemporary development, the code it generates makes
the UNIX C compiler seem almost like a toy (although C could self-host,
unlike BLISS-11).

In those days, there was very much a belief in the "systems" community that
you had to write in assembler for any "real" or "production."  Famously,
Wulf took a bunch of his best BLISS programmers and the best PDP-11
programmers they knew and gave them a bunch of functions/programs to
write.   It turned out that for any code longer than 10 lines of assembler,
BLISS did as well as or better.    The CMU BLISS compiler is discussed in
the "Green Book," and after that experiment, quickly became the "how-to
manual" for compiler code generation/optimization:
[image: BLISS_GreenBook_Cover.png]
Gordon Bell was on the CMU faculty in those days, and he brought BLISS to
DEC (and a number of former Wulf's students became the core of the DEC Tech
Languages Group - TLG).  BLISS quickly became the primary system
programming language for most everything (note Culter hated BLISS - which
is why VMS was written in assembler, but that's a different story).  I've
written elsewhere about the huge mistake DEC marketing made (they were
charging $5K per CPU, so too few customers ended up buying it).    Yes, the
ARPA research community (CMU, MIT, Stanford, et al) all had it, as did a
lot of DOD/DOE contractors, but for the rest of the world, particularly
universities, when you had the sources to C (and it was self-hosting) and
came with UNIX all for $100, it wasn't a fair fight. †

As for the IBM 360 family, at some point, one of Gary Kildall's (of CP/M
fame - remember he was a compiler researcher, not an OS one) students at
the Naval Postgraduate School wrote a 360 ISA target; but I don't remember
the OS target for the original 360 compiler.   CMU was also famously a
360/67 TSS shop.  I don't remember if CMU took it back and did the TSS
support; but it was on our 360/67 (along with PL/360 from Stanford) when I
worked in the computer center.  I think I may still have some of the docs.

Note, Bell Labs was also TSS Shop (ISTR that the original Unix port ran
under TSS - Tom, did you remember?).

Clem


† I've also mentioned I learned BLISS before C and was really disappointed
with Dennis' compiler when I first saw it.  But I quickly joined the C team
when I realized it was much easier to write and compile programs (the
PDP-10s and 20s were always way overloaded).

On Sun, Jul 12, 2026 at 3:27 PM John Levine via TUHS <tuhs at tuhs.org> wrote:

> It appears that Tom Lyon via TUHS <pugs78 at gmail.com> said:
> >I finally managed to extract and format this document.
> >Read it if you're in to horror literature!
> >
> >It comes from the 'memo' file in
> >
> https://www.tuhs.org/Archive/Distributions/IBM/370/370_c_virgin_source.tar.gz
> >
> >PDF here:
> >
> https://drive.google.com/file/d/1eVfRW8QS7M11MfK4kFaWRMZLXtuLWjSj/view?usp=sharing
>
> I'm intrigued by the references to BLISS on TSS.  Is that the same BLISS
> as on DEC
> macines?  I never heard of a 370 version and neither has Wikipedia.
>