TI-81

since unknown year (earliest usage recorded on this site was 1995)

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minder

minder - 5 years

minder

1995–1999

We used that in highschool. Me and my friends had a hacking contest on these. My friend wrote full-blown CoreWars system (he used two TI-81s - one for compiling warriors and the other for MARS) and eventually won the contest :)