@nina LED matrices are too cool

You know what? Fuck you

*Makes own PIS on your train*

the LED matrices are 19 LTP2157AHR.

mapping out the pins of the top board connector, we get:

pin 1 vcc
pin 2 A/B first shift register
pin 3 shift register clock
pins 4 to 10 row
pins 11 and 12 gnd

essentially, the columns are selected using a long chain of shift registers, while the rows are powered directly

To get it working again, I'll likely need to design a board that can fit, and ditch the water damaged bottom logic board. The top board is only lightly damaged and likely just needs a bit of cleaning.

The main ICs are an Intel 8031P from 1981 paired with 16K of Toshiba TC5517AP-2 RAM. The code is presumably stored on the 64K TMS2764-25JL EPROM. there's a tiny sticker with the TI logo and the "21" characters, covering the quartz window for erasing the contents. I'll later read all the data still on there.

this is the bottom board, there's a small print on the green connector holding the two boards together saying "28 MAR 1987".

you're supposed to program the message using that custom 16pin IDC connector, but i can't find any information about the circuit without tracing the PCB.

looks like this thing has been suffering for quite a while, there's lots of water damage here

the main LED circuit inside is composed of a SN74LS164N parallel shift registers from Texas Instruments followed by two SN7406N hex inverter buffers/drivers. If you've worked with these kinds of matrix displays before, you can probably guess how it works

from the italian text on the back, i think it's quite old, and there's also no information about this device on the internet. translated:

"Message kept in memory > 6 months"

"Max absorbed power: 36VA COSφ 0.7"

"recently" got my hands on this LED matrix display, "SAREMA VIDEO SPEAKER 150" for a few bucks. let's see what's inside

#hardware #electronics #led

@siguza zstd is WAY better for zip bombs, they get nice and tight, but i want to try making a generator that makes them look like HTML and not just full of NULs or something, and i would like for it to make the zip bombs unique (e.g. crafting a brand new zip bomb on every request, if i can do it fast enough)

for example, 10GiB of NULs is ~300KiB on zstd as opposed to gzip

Windows is making a great argument for linux today

@siguza yes, then add some HTTP/HTML look-alike strings to fool the decoders into trying to decode all of it, and you should get some pretty nice zip bombs

@siguza transport and content encoding afaik

@capetaun quelli dell'esselunga con le ruote 😭

Alice and Bob are tied to two separate trolley tracks. Neither of them know that the other is implicated in this scheme. Mallory can choose to let the trolley run over and kill Alice, or they can divert the trolley to kill Bob instead. Mallory can then steal the private keys from the victim, and assume their identity (Alice and Bob assume Linux is backdoored so they store their private keys on physical objects they keep on their persons. the threat model is very complex and this is a reasonable precaution). Mallory must now pretend to be the victim to extract information from the survivor; assume their message history has perfect forward secrecy and Mallory cannot read it.

How should Alice and Bob prepare for this inevitability, who should Mallory assume the identity of, and what is Mallory's optimal strategy to avoid detection by the survivor?

Every now and then when my blog gets attention, *especially* when the "How Decentralized Is Bluesky Really" post came out, you get a bunch of people complaining that the site looks like it was designed 20 years ago (it was)

@mkljczk made a "more modern version" of my blog https://mkljczk.pl/uploads/how-decentralized-is-bluesky/

Compare to the original https://dustycloud.org/blog/how-decentralized-is-bluesky/

Big step up!

@fasterthanlime 🏀