Unexpected blast from the past listening to @shanselman interview Mekka Williams. She and I both used the SL-1 language in our first jobs out of college, and we both used it to program telecom equipment.
I was a Bell Northern Research from 1979 to 1983, programming the SL-1 private branch exchange (PBX). I remember debugging by setting breakpoints using a hardware debugging card with 16 red LEDs and 16 switches to specify the address.
https://hanselminutes.com/869/do-i-stay-or-do-i-go-tech-career-advice-with-mekka-williams
