let's take apart this old chart recorder!
umm, that's a lot of analog! mostly ceramic DIP packages, too.
the LED bargraphs are driven by two FPGAs and a whole pile of latches.
there's... even more boards underneath.
next layer: even more FPGAs. some ROMs too.
the processor board has an Intel 186 on it! just what I suspected.
feast your ocular orbs on this very old Intel flash memory chip, complete with 80s logo.
the bottom board controls the thermal printer. lots of GALs, FIFOs, and SRAM.
this is the fattest little delay line i've ever seen
looks like the onboard EPROM is just a bootloader. the real software is in the two flash memory chips that are soldered down. 🤔
check out the memory card in this thing. it is not PCMCIA, it's something called Melcard and it has a cute little shutter covering the edge connector.
gonna try to dump the flash memory. too bad it's soldered down--wait
oh, there's german in the flash! 256kB of text and code.
all right, can any of you think of a reason *not* to part this thing out? the rubber roller is turning into goo and staining the paper.

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More from @TubeTimeUS

Feb 8
this is the computer you wanted to have in your electronics lab in 1983. it's like a cross between a scientific calculator and a computer. it runs BASIC, has a built-in printer, CRT, and tape drive. an HP-IB add-on lets it talk to GPIB instruments.

...and mine is broken! ImageImageImage
hmm. Image
here's the main board. there are test points for voltages and the four clock signals. Image
Read 17 tweets
Jan 26
let's do cool things with piezoelectric barbeque ignitors! 🧵
first we ought to cut one in half. they're pretty cool inside!
how it works: when you push the button, the metal hammer snags on plastic ledge, and the left spring (heavy) compresses. as you continue to push the button, a wedge lifts up the hammer and it SNAPS off the ledge, slamming into the piezo, which changes force into electricity.🎇
Read 21 tweets
Jan 19
oh hai! it's a new arrival: an HP 150. it's a semi-compatible PC from 1983. it runs MS-DOS. Image
there's even a built-in thermal printer in the top! Image
on the back it has two serial ports, the keyboard port, and an HPIB port. there are also two expansion slots on the bottom. Image
Read 153 tweets
Jan 18
finally got one of these cool MFM hard drive emulator boards! it can pretend to be a hard drive or it can analyze one. Image
plugged into one of my ST-412 drives. Image
it works! Image
Read 15 tweets
Jan 17
this is the story of a weird old ROM chip -- with a mystery that i'm going to try to solve. 🧵 Image
here is what i know: it was manufactured by Signetics in 1974, so it's about 48 years old.
it is very similar to the ROM chip that was used in the Apple 1, but not identical. something is different. Image
Read 73 tweets
Jan 12
what is this chip? Image
i mean c'mon folks, it's got the part number right on the top! and the date code, and the whatever code
I have a tube full of these things. it's a very old style of tube. Image
Read 36 tweets

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