Gregory's Server
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 @tubetime Sescosem was formed during the merger of Thomson-Brandt and CSF in 1968. Thomson's SESCO division was merged with CSF's COSEM division to form SESCOSEM. Sescosem's products were never a big commercial success, but the technology was eventually absorbed in the subsequent mergers that created STMicroelectronics. @tubetime I have a bunch of these in my parts bin they are quite common in the Netherlands (Europe). Probably don't exist anymore as I have only ever seen 74LS never any CMOS variants. ever need to monitor an 8-bit bus on a breadboard? I'm working on a better way. the bottom board has a TTL transparent latch and 8 LEDs. the top board is special... 🧵 this little guy turns the 8-bit value into hex! it's also configurable: you can flip the digits upside down for when you plug it into the left side of your breadboard. it can also trigger and latch data on the rising or falling edge of the optional trigger pulse, it can be level or edge sensitive, and you can set it to "single shot" capture a single value. some great pixel art from my brother. this was displayed with a genuine IBM CGA card (really!)
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 @tubetime that picture got some commander keen vibes going. And i don't think it's just the palette.
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@tubetime This is just subtle enough to make you double check your math and make sure you have it oriented in the correct polarity. Unless it's a bit too subtle and then you f#@k around and find out how much energy is in that misapplied capacitor. We used to say "just put a BFC across the output of that lumpy 48v full wave rectified transformer and you'll be fine" @tubetime being an electronics apprentice in the 1980s was sometimes a Trial By Fire. Charging a big High Voltage electrolytic cap, wrapping its leads around it and tossing it to the apprentice was a thing. Ow-diddly-ow. Then connecting a tantalum cap backwards across the output of a DC supply and switching it on just as the apprentice walks up… Good Times? cross section of a high power electric car charging cable. the electric current is so high that the copper wires would overheat, but coolant flows through small tubes in the center of each wire.
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 @tubetime holy crap, is all of this so that it can support an essentially infinite/full duty cycle? I mean I’ve lugged 4160V cables and they don’t need this (I mean, yes, they’re AC and high voltage specifically to reduce current and the resultant heat from I-squared R losses, but still) here's an interesting card that came in for attempted repair: a Hercules MC1024 Micro Channel video card. it uses the weird Micro Channel bus, and it is based around the TIGA graphics processor. and it appears to from the computer have been untimely ripp'd. this is how KiCad has been marking pin 1 on a lot of devices. yes, it's a silkscreen line that is slightly longer on one side than the other. because silkscreen never flakes away or gets obscured by a via or clipped by a fab vendor for being too close to a solder mask opening... in my own libraries, i like to use multiple markings for pin 1. here i have a semicircle at one end of the chip along with a circle right next to pin 1. @tubetime Long overdue. I had no idea they were following a standard, its a terrible standard. I've reversed SWD connections a half dozen times because a coworker decided to orient the connector unintuitively and made no attempt to augment the default terrible pin one marker. I got nerd sniped into helping reverse engineer this card. it's a rare beast -- the interface card for an IBM 5364. this midrange System/36 minicomputer was paired with a PC for bootstrapping and control. the interface between the two is a 62-pin cable and a special card that goes in the PC. these often get separated and lost. i just love it how STEP models for electronic components are all locked down now 🙄 and also obviously wrong like this "7-segment" display.
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the scan was a little tricky to stitch together since the board is longer than my scanner 😅 
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@tubetime You can just drag a line through all the capacitors. Watching that copy/paste operation w as painful :-) doing research on refurbishing old hard drives, and i learned that the platters are typically coated with a PFPE-based oil.
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@tubetime This means I shouldn't use them as a serving dish! Y'know, because the big spindle hole isn't enough deterrent :) so i have picked up an INS8900D, also known as the National Semiconductor PACE. it is the first commercial 16-bit microprocessor. let's take it for a spin!
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@tubetime from the description on https://www.cpu-world.com/CPUs/PACE/index.html it sounds like a nice architecture but unfortunately very slow.  @tubetime AFAIK NSC only called the original PMOS version PACE, and always referred to the NMOS version by the INS8900 part number. help solve a mystery! my friend has this Thinkpad. the LCD powers up fine, but slowly fades to white starting from around the edges of the screen. after powering it off and letting it sit for a few hours, it powers up fine again. got any ideas?
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 @tubetime @tubetime Hi, it‘s maybe a loose connection of one of the LCD bias voltages. As there is only minimal current flow, the Panel charges up with time? the 74187 is a 1024-bit ROM (arranged as 256 x 4 bits). i was surprised to see this in my collection since this is a mask ROM device -- typically these have a custom marking on top. ...and yes, there seems to be data in this chip, but it is mostly zeros. in contrast, the 74LS471 is a 2048 bit PROM (arranged as 256 x 8 bits). looks like i can program it using my Allmax programmer! the 74HC942 is a Bell 103-compatible 300 baud modem, all in one chip! you'd need quite a bit of external circuitry to interface it to the phone line, however.  @tubetime Given that 1983 date code I wonder if that chip was on my Hayes Micromodem IIe in my Apple II.  i was looking at the Wikipedia list of 7400 chips (https://en.wikipedia.org/wiki/List_of_7400-series_integrated_circuits) and noticed some really unusual devices.🧵 see, over the past few days i've been sorting through a *ton* of chips that i recently got. and, as it turns out, i actually *have* several of the truly strange devices in the 74xx family. so let's take a look! |
@tubetime Might be SEMI PROCESSES, INC. https://opencorporates.com/companies/us_ca/0827527
@tubetime could be this one https://www.spisemicon.com/category/about/spi-semicon-north-america/
@tubetime
Semi Processes Inc.
https://www.questcomp.com/part/4/sp74hc113n/384845007
At this page there is also a data sheet.