How did you get your hands at liquid nitrogen as a kid?

You can just buy it at the appropriate gas supplier, my local university used to sell it. If your parent was a nerd or a welder it would be fairly easy, it can just be expensive getting an appropriately sized dewar if a thermos isn’t big enough for your usage (or if you can’t find someone willing to sell you only a thermosful, which is admittedly a little dangerous)

My physics department had a spigot coming out the wall and sheet with the number of liters you poured yourself. It was about the price of milk.

This is exactly correct. The nerd/hacker acorn doesn’t fall far from the nerd/hacker tree.

Same reason I had a spare 286 lying around

My university was the only place in my city that had a plant for liquid nitrogen so they supplied all the hospitals. They also were pretty cool about giving it out, so you could do diy ice cream or minor cosmetic procedures.

My dad got it just to play with on a couple of occasions. We froze and reanimated brine shrimp once..blew up a 2 liter bottle (do not attempt - it was really loud). He just got it from a gas supply - I’m sure it’s the same situation today. The liquid nitrogen itself is fairly inexpensive, but you need to rent a special container for it.

Dewar flask is the container. Hospitals also have liquid gasses but don't usually sell it directly.

Dude, that's cool! Now I have to look around if someone has anything similar.

I was always trying to find ways to improve the performance of my systems when I was a kid. Tweaking configs, removing bloat, stealing components from my parents systems. I would've loved to have tried what you did!

> It was more a situation of being a computer nerd at exactly the right time and place so that it was possible to really impress adults with minimal actual effort

Oh, I know that feeling.

Blew one teacher's mind by doing animations on the RISC OS machines at school, they didn't know it was even possible.

4D-maze visualisation and route-finding at university.

What was weird was all the times I've shown people Word Lens or Google Translate, augmented reality translations blew the minds of other developers even a decade after that was demonstrated.

Right time and place.

How did this work? 286 didn't have free clock scaling. Cooling it could make it use less power I guess, by lowering internal resistances, but that won't make it run faster, it's still running based on the clock rate.

More importantly, a hot CPU wouldn't perform worse, it would just break at some point when a computation got the wrong result.

How did this work?

By swapping crystal oscillators with a higher frequency.

And just yesterday, I was remembering a 6th grade science experiment that involved a radar gun that my father "borrowed" from a police dept (I suspect he paid to borrow or bought it outright and didn't tell me) and how that was somewhat sophisticated compared to the projects of other kids.

Really put me in my place with this one. Nice work.

Older CPUs didn't have a range of performance. They either worked at a clock speed, or didn't. If you put in a very high rate crystal, the CPU would either work at that higher rate without cooling, or not work without cooling. Clock speed was a constant.

>I didn’t even measure the clock speed - just wrote a little program (I think it was in QBasic) that calculated factorials or something (don’t remember the details), then measured performance difference between no cooling, ice water, and liquid nitrogen.

>My measurement technique was extremely simplistic - how much wall clock time does it take to do this computationally-intensive task. It ran faster with ice water, and even faster with the liquid nitrogen (until it died from condensation).

There is no world in which a 286 has a program that runs "slow" without cooling, and fast with cooling. If a clock speed "needs cooling", it's because the CPU crashes otherwise. If jdenning changed the crystal, THAT'S what increased the CPU speed. They seem adamant that wasn't the case though.