The Fortran H compiler was mostly written in Fortran: 27,415 lines of Fortran and 16,721 lines of assembler according to slide 12 of [1]. There were some language extensions (structures and pointers) to support this, enabled by the secret compiler option XL. They are described in Appendix J of the Program Logic Manual for the compiler [2]. The early-1980s Fortran 77 compiler for the GEC 4090 was written in Babbage, a thin PL/360-like veneer over the raw 4090 instruction set. [1] http://booksite.elsevier.com/9780120884780/Graduate_Lecture_Slides/Core_Lec… [2] http://www.bitsavers.org/pdf/ibm/360/fortran/Y28-6642-3_FortH_PLM_Nov68.pdf

On 12/4/18, Clem Cole <clemc(a)ccc.com> wrote: Unfortunately I can't give much of DEC's compiler history as I was a member of the software development tools team at the time. I didn't pay too much attention to what was going on with the VAX compilers. I moved to the compiler world in 1985 as part of the GEM compiler back end team, which was tasked with developing a new, common back end to replace the various VAX code generators going forward. The compiler guys wanted to concentrate on optimization and code generation, so they hired me--a software development tools guy--to design and implement the non-compiler parts of the back end such as command line parsing, heap memory management, file I/O, and object file generation. Over the years GEM was targeted to MIPS, PRISM, Alpha, and Itanium machine architectures, and VMS, Unix, Linux, and Windows NT operating systems. We were working on x86 when Compaq sold the Alpha architecture and its engineering team (including GEM) to Intel. Intel never did anything with the GEM technology. BLISS was DEC engineering's official implementation language. BLISS-32 was used for the VAX. I'm pretty sure VAX Fortran, VAX COBOL, VAX BASIC, and VAX Pascal were all written in BLISS. They all had their own independently developed code generators. VAX C and VAX PL/I were written by Dave Cutler's compiler group in the late 70s/early 80s. They shared a common back end called the VAX Code Generator (VCG). I don't know what the implementation language for VCG was; I think it was C (Dave Cutler was not a BLISS fan). VAX PL/I used the Frieburghouse PL/I front end, which I think was written in C. VAX Ada was also VCG-based; the front end was written in BLISS. VAXeln Pascal might have been written in Pascal. All of DEC's Alpha compilers used GEM as the back end. There was also a VAX MACRO GEM-based compiler that took VAX assembler as its input language and generated native Alpha code. GEM was originally completely written in BLISS, but in the mid-1980s I started rewriting the modules under my control in the common subset of C/C++ to take advantage of strong typing (BLISS has no data typing whatsoever). DEC C/C++ for Alpha used the Edison Design Group C/C++ front end. DEC acquired COMPASS's compiler technology and DEC Fortran used the COMPASS Fortran front end to support Fortran 90. That code is written in C. -Paul W.

On Tuesday, 4 December 2018 at 15:59:46 -0500, Paul Winalski wrote: Was this a start-from-scratch operation? The original Tandem OS (called Guardian at the time) was written in Tandem's TAL (Transaction Application Language, amongst other productions), a vague evolution of HP's SPL that looked more like Algol, starting in about 1974. That is also the earliest I know of an operating system being implemented entirely in a high level language. When Tandem started using other architectures (MIPS) in the late 1980s we discussed translating the whole thing to C. I was asked to write a 99% translator (maintaining comments and such), and failed. I lost track of the system after that, but it seems surprising that they would have started again from scratch. Greg -- Sent from my desktop computer. Finger grog(a)lemis.com for PGP public key. See complete headers for address and phone numbers. This message is digitally signed. If your Microsoft mail program reports problems, please read http://lemis.com/broken-MUA

On 12/4/18, Paul Winalski <paul.winalski(a)gmail.com> wrote: Typo. I meant to say "mid-1990s". -Paul W.