In Memoriam: David N. Williams (1934 -- 2024)

I only found out today that Prof. David N. Williams had passed away in March, 2024.
https://lsa.umich.edu/physics/people/in-memoriam/williams.html
I had not seen any recent posts here in comp.lang.forth from David for some time now. The last post of his which I could find was on 24 December 2023.
I don't know exactly when he and I corresponded separately from c.l.f. but it has been more than 17 years. David was interested in a number of Forth systems, and in writing Forth code. He was particularly interested in developing tests for Forth systems and libraries. He and Guido Draheim and I discussed features of PFE (the portable Forth environment), for which Guido had taken over maintenance and development. I believe David contributed significantly to PFE, while I was using PFE as a reference system for testing and developing kForth. The three of us had many email discussions for a time.
In 2006, David expressed interest in porting kForth to the PowerPC-based Macs, and I was happy to help him. He wrote the ppc assembly virtual machine (released under LGPL), and I recall that I didn't have to do much with the C++ and C parts of kForth, except for a few issues of endian-ness. David helped bring considerable structure to the kForth assembler vm by introducing the use of macros, the legacy of which remains in the kForth code today. Perhaps more importantly, with regard to kForth development, he wrote the automated regressions tests for kForth to aid him in developed the ppc assembly code. The tests are instrumental in my development today, for the x86/x86_64 version. Much of his library test code will also be found in the kForth packages, such as for the libgmp and libmpfr interfaces.
David also contributed to the Forth Scientific Library by extending Prof. Julian Noble's complex arithmetic library, and also developing automated tests for that library. He also developed tests for IEEE floating point arithmetic. Forth would not be as robust today for scientific computing without David's considerable effort.
Apart from Forth, I was able to pester David with some physics ideas I was developing. He responded with some positive comments and very kindly pointed out a glaring deficiency with a draft of a paper I had sent him, correcting my picture of the allowed angular momentum projections for photons. We both tried to salvage what I had done. The paper remains on the shelf today and I hope to return to it some day.
I will deeply miss the connection I made with him, both in regard to the Forth language and in physics.
--
Krishna Myneni