That's Mitch Bradley's Open Firmware Forth, which was also on Suns, post-NuBus PowerPC Macs, Pegasos, and IBM Power Systems!

I used to call it "L1-A Forth", because that's the Forth you got when you pressed "L1-A" on a Sun keyboard to get into the boot monitor. He also made a great version of that Forth system with a metacompiler that ran under Unix (Forthmacs), which I used a lot.

https://github.com/MitchBradley

https://github.com/MitchBradley/openfirmware

https://en.wikipedia.org/wiki/Open_Firmware

https://elinux.org/Flameman/openfirmware-apple

http://macos9lives.com/smforum/index.php?topic=1965.0

https://github.com/ForthHub/ForthFreak/blob/master/Forthmacs