this Tesla SUV ran into a traffic barrier at 70mph while on Autopilot. how could this happen? there are 3 major contributing causes, and they're *fascinating*
before we dig into the causes, let's set the scene first: the southbound 101 freeway at the intersection of 85. there is a left exit ramp so commuter-lane traffic can get to the 85 southbound commuter lane.
the Tesla was in the commuter lane, then departed that lane and headed into the strip of roadway (called the "gore") leading up to the median, crashing into the barrier.
in 1990, a tiny company nobody had heard of, Cadtrak, sued Commodore for patent infringement and won. Their company CEO bragged that he put Commodore out of business! Commodore's downfall took more than just that, but who was Cadtrak, and what was their patent? 🧵
first, the patent. 4,197,590, filed in 1978. it described a method for drawing a cursor and then erasing it again without having to store a copy of the background. this was a simple XOR operation.
you see, with an XOR, a '1' bit in the cursor caused whatever graphics were on the screen to get inverted. XOR it again with the same bit, and it gets inverted back to the original state. a '0' bit made no change. this saves RAM, since you don't need to keep a backup image.
this neon lamp should never light up! there's a fascinating reason why... 🧵
ok so what is the circuit? this is a 3Com Etherlink card from the late 1980s. you can see the neon lamp in the lower right. actually there's a bunch of other interesting things going on but first, the neon lamp!
the circuit on the right side of the Ethernet card interfaces to the external AUI transceiver (the 15-pin D-sub) or a coaxial 10Base-2 network. the whole circuit is isolated by those two transformers, and i've put a red line so you can see no traces cross over.
this desk fan is 85 years old and still running strong. how would YOU design an electronics gadget to last 100 years? what components would you use? what potential failures would you expect?
bonus: how would you make it last 200 years? how about 500 years?
thanks for all the responses. i noticed some interesting patterns:
✅assume humans are around the whole time, so make it easy to repair. *lots* of subtlety to unpack on this one.
✅material choice is critical
✅keep it as simple as possible, but as complex as is needed.
honestly i didn't think of the repair thing even though it may seem obvious. i guess i was thinking about a device that could survive 200 years in a dusty closet. but repair is very important!
first up is the MOnSter 6502, the world's largest 6502 microprocessor. (you may have seen my pinned tweet about it). the 6502 is a microprocessor that was the heart of the original NES, the Apple II, the Commodore 64, the BBC micro, and more.
this electrical transmission tower has a little problem. can you spot it? actually, it's not a small problem--it cost us 16.65 *billion* dollars and caused the deaths of 85 people.
here's what it is supposed to look like. a transposition tower rotates the relative position of the three phase wires. this is done to balance the impedance of each of the wires so that one of them doesn't hog current.
here's the problem. the jumper conductor (the horizontal piece that brings a conductor from one side of the tower to the other) has fallen down. you can see the insulator dangling (circled.) but why did it fall?
here's a fun piece of (very) 1990s hardware: the Snappy Video Snapshop, from a company called Play, Inc. it is a video digitizer, so video goes in one end...
...and the other end plugs into your computer's *printer* port! no USB back then, so this was how many peripherals connected to your computer, including CD-ROM drives, tape drives, even network adapters.
The new Intel logo represents a dramatic simplification of the Intel brand identity. Crafted with an underlying geometry, the logo has a refined symmetry, balance, and proportion that is understated and -- some may say -- iconic.