On Sun, Feb 2, 2020 at 10:47 PM Larry McVoy <lm@mcvoy.com> wrote:

How big was it 30 years ago? In my opinion, tiny compared to C.

Be careful, Fortran use is still not tiny (it has always paid my salary, and continues to do so). If you want to see some of the detail check out a fascinating web site: http://www.archer.ac.uk/status/codes/ then scroll the red bar and button, by programming language and take a look at the graphics, then scroll down and look at the applications. [Archer is a big Top-500 style supercomputer in the UK. They are one of my customers, so I'm aware of their work].

The sad truth is not a lot of 'new code' gets written for HPC (what I call the 'Fortran problem' - a discussion I have had with a number of the DPC++ folks here at Intel). Solutions like University of Illinois HPVM (Heterogeneous Parallel Systems Compiler), DPC++, and Cuda for that matter, all assume new code is being written (which is great for minting new Ph’Ds), but history has shown over and over, that does not happen in the HPC space [See: Clem Cole's Quora answer: Why is the Fortran language still in use and the most Importantly Relevant in HPC? Is it just because this Language has Tremendous Numerical Calculation Capability Which is an Important Part of HPC? and Clem Cole's Quora answer to: What is Fortran Useful For?].

So back to the question. Given the timeframe when Voyager was being developed, the primary development languages were Assembler, and Fortran-66/IV in the NASA community (with some Jovial, most from the AF types as I understand it). Systems programming languages such as BCPL, C, BLISS, et. al were not yet in fashion in the wider world, although the system developers and research types certainly wanted something "better." Remember, only a 5-6 years earlier Margaret Hamilton wrote the AGC system SW at MIT/Draper in assembler. Ane when this SW was being written, Bill Wulf would not do the famous BLISS vs. PDP-11/PDP-10 assembler test study (~73) at CMU.

Frankly, I would have expected the folks at this(these) NASA contractor(s) to have used assembler in those days under the guise of "efficiency;" but Fortran-IV would definitely have been popular at many contractors that would have been doing the work. The article mentions Fortran-V which I find interesting because I did not believe it was really much of a thing (i.e. it was never standardized). Basically, as I understood it from my Fortran peeps at DEC/Intel, F-V was the Waterloo extensions (a.k.a. WatFor) that got picked up by most people and in particular, IBM added to the FORTRAN/G or H compiler for the S/360. DEC had gone in a different direction still with VMS FORTRAN, although I believe they had picked up the things like WRITE(*) from Waterloo.

I could be misinformed, but I thought that it was not until the Stu Feldman led what be called the Fortran-77 standard (which IIRC was not completed until sometime in the early 1980s), that the ISO standard actually moved from Fortran-IV. [As, I have said elsewhere, the greatest bit of marketing DEC ever did was convince the world VMS FORTRAN was F77].

So it would not have been out of the question for the Nasa team to have used a flavor of post FORTRAN-66/IV as a development like the article Dennis points to suggests. But I wish I knew what the ISA of the processor was/is? That would likely tell us more. What were the HLL available for that processor? Did NASA invest in having something beyond the assembler written?

Clem