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29 Nov, 5 tweets, 2 min read

i'm happy to announce the release of my latest sound card, the Snark Barker MCA! this is a Sound Blaster compatible card designed for Micro Channel bus computers, including the IBM PS/2 family.

the full open-source design is available here: github.com/schlae/snark-b…

this is not a product that i plan to sell, but it is a design that technically-inclined folks can fabricate.

fortunately, due to the permissive open-source license, others can fabricate and sell the cards!

https://twitter.com/TubeTimeUS/status/1299181646755708928

here's the epic design thread. this card was a lot of work to design and troubleshoot!

https://twitter.com/TubeTimeUS/status/1299181646755708928

so why design a sound card for a PC bus that hasn't been used in 25 years? this is why:

ebay.com/itm/CT-5320-B-…

here's the blank board for your inspection. see anything odd about the silkscreen text?

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30 Nov

here's the wire-wrapped prototype of the original IBM PC (5150) motherboard!

this thing just *screams* IBM. the yellow wire was IBM's standard prototyping/bodge wire. to strip the wire, just crimp it with pliers and it peels off like a banana.

see? just like 🍌

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5 Nov

here is part of the payload electronics from the Explorer 8 satellite (1960)! look at all the machined phenolic, colorful hand-tied wiring harness, and the stacks of round circuit modules! 🧵

there were apparently two of these columns of electronics. someone's taken apart the second column and we can have a look at some of the modules inside. they are *glorious* 🥰

i was expecting Explorer 8 to look pencil-shaped but it actually has this sort of bulge in the middle. i can't find a diagram showing how the stacked electronics were placed inside.

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23 Oct

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.

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20 Oct

this ought to take a while to print.

not too shabby

that took 7 hours to print 😂

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18 Oct

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.

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