Wolmania - Friday, April 1, 2022

Depending on whom you ask, the month of April's name comes from either: a) the Latin word aperio, “to open (bud)”, because plants begin to grow in this month; or b) ¯\_(ツ)_/¯. I spent a little while just now trying to come up with an Air Bud joke but couldn't quite land the plane. Probably for the best.

Anyway, it's a new month. Might be a good one. Hope you enjoy the newsletter today.

Item 0: follow-up

Item 1: a link

What Hath Woz Wrought

Andy Hertzfeld writes about his 1979 efforts to write software for a cute little thermal printer for the Apple II:

Vic was worried about the possibility of the software crashing while it was printing. It was possible for a thermal element to be inadvertently left on indefinitely, which could potentially ruin the thermal elements or even cause a fire. Vic solved the problem by adding a bit of hardware to cut current to elements that were left on for more than 10 milliseconds. He asked me to write a test to verify that his precaution was working as intended.

I wrote code to intentionally leave each thermal element on, to verify that Vic’s safety measure was effective. I was pleased to see that it worked perfectly, but also a little disappointed to miss more exciting behavior if it hadn’t. I thought of something else to try: what if I left an element on for 9.9 milliseconds, before turning it off for only 30 microseconds, then turning it back on again. It would effectively be on for more than 99% of the time while sidestepping Vic’s remedy. I couldn’t resist coding it up to see what would happen, so I fired up the modified test and nervously awaited the results.

At first nothing seemed to happen, except for a low volume humming sound emanating from the printer. Suddenly, after about five seconds, the paper started turning a deep, inky black, spreading out from the print-head organically, almost like a liquid, darker than I had ever seen before. I started smelling an acrid odor and noticed there were open flames near the print-head beginning to spread. I quickly reset the Apple II as I smothered the fire with my jacket. The foul smell drew a small crowd but mercifully no fire alarm.

Unfortunately, the experiment seemed to permanently damage the print-head; it burned out or possibly melted some of the thermal elements. The printer could no longer print text or graphics, but it still was able to set the paper on fire, so I kept it around for the occasional incendiary demo.

Very fun to skim through all these stories of early, scrappy Apple knowing how everything turned out. Here's a bonus printer-related early Apple story.

Item 2: a list

Musical decades, ranked:

1. 1980s
2. 1970s
3. 2000s
4. 1960s
5. 2020s [guessing/hedging my bets here]
6. 1950s
7. 1990s
8. 1940s
9. 2010s

Item 3: a media recommendation

Not that you don't always watch the videos, but you should really watch this video, it's very short and interesting!

Item 4: a photograph

See ya!

Thanks for reading and have a good weekend. See you back here again next week.