For this month's UKSTUG meeting, Dave Mason will talk about Zag Smalltalk, a new Smalltalk VM written in Zig. Dave Mason ( http://sarg.ryerson.ca/dmason/ ) has been a professor of Computer Science at Toronto Metropolitan University (previously known as Ryerson) for 41 years. He has done research on operating systems, software reliability and programming languages. Current research is mostly around Smalltalk and other dynamic languages. If forced to program very low level projects such as virtual machines, he is willing to use Zig or Rust, but for any other purpose, he insists on using higher productivity languages - primarily Smalltalk. Zag Smalltalk ( https://github.com/dvmason/Zag-Smalltalk ) is a principle-based Smalltalk VM. "Principled" means that the only 3 operations are: message send, assignment, and return. 1) it is designed from the ground up to use multi-processing, to leverage multi-core systems. 2) There is no special-casing of methods like ifTrue:ifFalse or whileTrue:, although of course some methods are implemented by primitive methods. It does aggressive inlining of methods and blocks. 3) “Source” code is maintained as ASTs. 4) Compiled code runs in a dual form of threaded code and JIT’ed machine code that seamlessly interoperate. 5) It has a partially-copying and partially-non-moving garbage collector. 6) It keeps many more values as immediate, including symbols. 7) It uses a single-level dispatch mechanism to implement Smalltalk dispatch semantics The research question is, "Can this be made fast enough to be competitive?” Preliminary results are encouraging. This will be an online meeting from home. If you'd like to join us, please sign up in advance on the meeting's Meetup page ( https://www.meetup.com/ukstug/events/290036186 ) to receive the meeting details.