ITI Audio/Sontec is known for world-class analog mastering equipment, but in the 80s they designed and prototyped a FORTH computer based on the Rockwell R6500 series CPUs:
Here's a picture of the last assembled stage of prototyping:
There's actually a further revision for which we have acetate artwork and a blank prototype board, but the schematics have been lost, and the prototype is from the 1980s and does not have plated-through holes! The Sontec FORTH computer was a big inspiration for our own R65X1Q SBC:
I've gotten it running, and reverse engineered the bodge board enough to replace it with a GAL (I've written the PALASM but have not yet dropped it in, it'll require one jumper modification). This board was also largely the inspiration for the R65X1Q SBC!
