NeWS didn't use FORTH. But HyperTIES used both FORTH and NeWS because there were a lot of things that FORTH could do that NeWS couldn't, like link and call C code directly.
The FORTH I used was Mitch Bradley's "Sun Forth", aka "Forthmacs" (with the Jove ersatz Emacs editor by Jonathan Payne built in), which eventually evolved into OpenFirmware, and which was once defined by an IEEE standard, "IEEE 1275-1994", but it was withdrawn because the standard was not reaffirmed:
>Open Firmware is described by IEEE standard IEEE 1275-1994, which was not reaffirmed by the Open Firmware Working Group (OFWG) since 1998 and has therefore been officially withdrawn by IEEE.
It's still alive and maintained and used for many things. Here's the source code, called OpenBIOS, as well as some other implementations and versions:
The FORTH I used was Mitch Bradley's "Sun Forth", aka "Forthmacs" (with the Jove ersatz Emacs editor by Jonathan Payne built in), which eventually evolved into OpenFirmware, and which was once defined by an IEEE standard, "IEEE 1275-1994", but it was withdrawn because the standard was not reaffirmed:
https://en.wikipedia.org/wiki/Open_Firmware
>Open Firmware is described by IEEE standard IEEE 1275-1994, which was not reaffirmed by the Open Firmware Working Group (OFWG) since 1998 and has therefore been officially withdrawn by IEEE.
It's still alive and maintained and used for many things. Here's the source code, called OpenBIOS, as well as some other implementations and versions:
https://github.com/openbios
https://github.com/openbios/openbios
https://github.com/openbios/openfirmware
https://github.com/openbios/openboot
https://github.com/openbios/smartfirmware
https://openfirmware.info/Welcome_to_OpenBIOS
https://openfirmware.info/Open_Firmware
https://github.com/MitchBradley/openfirmware
Also there's also Mitch's very portable "cforth":
https://github.com/MitchBradley/cforth
There's even an Open Firmware Song:
https://www.youtube.com/watch?v=b8Wyvb9GotM