from the link: "using 30-year-old or older machines."
from the fine article: "First released in 1981; discontinued in 1994 using 30-year-old or older machines."
I recently (three weekends ago) fired up my Commodore PET 2001 (a *genuine* pre-1980 computer) and have been writing a Forth for it. It's really a lot of fun, and I'm finding that 30 years experience in various high-level languages has improved my "6502 assembler golf" game a lot. It's very incomplete, but the inner interpreter mostly works. Feel free to throw down on it here
"Kill the Wabbit, Kill the Wabbit, Kill the Wabbit!" -- Looney Tunes, "What's Opera Doc?" (1957, Chuck Jones)