I did nand2tetris something like 7 years ago, it was a pretty fun introduction to digital logic. I remember hitting a point where I couldn't continue after designing the ALU due to either a paywall, something missing, or the Java software being broken. Not sure if it's been fixed, but I'm guessing running in an older JVM would have probably worked.
I did it last year through Coursera (it's what pushed me to apply for my current master's program) and got the certificate, so I was able to complete everything. I don't remember there being any special measures taken on my end to get it to work. Dunno what the issue was, if something was fixed in the intervening time, or what.
