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IBM paperweight teardown: Reverse-engineering 1970s memory chips
- kens 6y agoAuthor here: anyone else have interesting IBM artifacts to discuss?
- colejohnson66 6y agoThose old IBM line printers... how were they so fast and (relatively) accurate? And why is my home printer so much slower? For example, the IBM 1403[0] Model 3 could supposedly do 1400 lines per minute(!) Even if I assume 100 lines per page, that's still 14 pages per minute. My home printer is lucky to do five. [0]: https://en.wikipedia.org/wiki/IBM_1403 https://en.wikipedia.org/wiki/IBM_1403
- codemac 6y ago$$$$$$$$$ Also the wikipedia link you pasted itself has a section on technology, and specifically how it was so much faster (pushed the paper into the ink rather than the ink into the paper).
- kens 6y agoI've done a lot with the classic IBM 1403 line printer. The basic idea is that a rotating chain has the characters on it and zips around at 90.3 inches per second. The printer has 132 hammers, one for each column on the page. When the right character lines up with a hammer, the hammer fires, printing the character. This lets the printer output a full line in 80 milliseconds. The details of the print chain process are much more complex than you'd expect (so feel free to skip this paragraph). The computer has to constantly check to see when a hammer should fire. One important thing is that only one hammer lines up with a character at a time. (It's physically impossible to fire all the hammers at once.) During this time, the computer reads the corresponding character from memory and fires the hammer if it matches. To make this work, the chain/hammer timing has to match the core memory cycle timing. The chain spacing is very slightly different from the hammer spacing, so you end up with a vernier effect where the aligned character position changes much faster than the chain actually moves. I made an animation that might make things clearer: http://righto.com/ibm1401/printchain.html http://righto.com/ibm1401/printchain.html Another thing that makes the printer fast is it has a hydraulic motor to advance the paper very quickly. Inconveniently, the printer at the Computer History Museum is leaking hydraulic fluid, so we need to mop it up regularly. (That's one advantage of your home printer.) The print quality of the 1403 line printer was much better than competitors because it used a chain instead of typebars or a drum. In particular, if the timing was a bit off, the chain caused the character to be shifted left or right. Other approaches caused the character to be shifted up or down. A left-right shift is barely noticeable, while an up-down shift makes the text look wavy and awful. By the way, a laser printer (e.g. Brother) is a good choice for a home printer if you want more speed and don't like the expense of ink.
- Johnny555 6y agoIt's not that hard to find a fast printer if print speed is important to you. I have a Brother MFCJ6535DW inkjet printer that's rated at 35 ppm black and white and 22 ppm color. I haven't measured it precisely, but it's doing at least 20 pages per minute. I think when it was new it cost around $500, but I got this one as a refurb for $180. (my wife works in a state regulated industry and prints a lot of paper - 500 - 1500 pages/month, so the printer gets a workout, and consumables are cheap - a 3000 page black ink cartridge costs around $25, about half the price as toner for our old laser printer and has no other consumables to replace like a fuser drum)
- eMGm4D0zgUAVXc7 6y agoHere's a fun IBM line printing video I've discovered thanks to your mention of those: The IBM 1401 mainframe runs "Edith" https://www.youtube.com/watch?v=LtlrITxB5qg https://www.youtube.com/watch?v=LtlrITxB5qg
- m463 6y agoI share your amazement. The thing was - they did everything mechanically. They were like chainsaws with accurate solenoids, in small soundproof booths.
- gnunez 6y agoThanks for your work Ken. I am learning so much from you.
- epc 6y agoI have a 2" square cube of the original IBM Armonk (now "North Castle") hideous orange carpet. They had to replace all of it after the fire in 1995 and offered anyone who had an office these cubes. Also an original IBM "Think" pad, though the leather is degrading (I grabbed it circa 1994 as Myers Corners was shutting down, really regret not just grabbing an entire box of them).
- joezydeco 6y ago@kenshirriff has an IBM "Technology Sample Kit" circa 1986 that looks pretty interesting: https://twitter.com/kenshirriff/status/1346517181098409985 https://twitter.com/kenshirriff/status/1346517181098409985
- kens 6y agoThat's me! kens == @kenshirriff The technology sample kit was discussed on HN last week: https://news.ycombinator.com/item?id=25893087 https://news.ycombinator.com/item?id=25893087
- joezydeco 6y agoAwesome! Love your Twitter feed!
- colejohnson66 6y agoLike how @dang is Dan G., @kens is Ken S. ;)
- donarb 6y agoI have a solar powered IBM calculator, the size of a credit card. Got it from an on-site IBM CE at the insurance company data center I worked at.
- nom 6y agoAll the vintage mainframe stuff is pretty mind blowing. There is an awesome hidden gem on YouTube: CPU Galaxy. He has a huge collection of vintage CPUs. IBM 9121 Mainframe CPU https://www.youtube.com/watch?v=s7lVfOi7su4 https://www.youtube.com/watch?v=s7lVfOi7su4 Dave from EEVBlog also made a video about it https://www.youtube.com/watch?v=xQ3oJlt4GrI https://www.youtube.com/watch?v=xQ3oJlt4GrI
- nicetryguy 6y agoNo sadly but i love watching you guys on CuriousMarc! Dissecting the past brings context and clarity to the present: What a wonderful gift. Your Alto reverse-engineering in particular was masterful wizardry. Thanks for everything you do!
- Syzygies 6y agoTwenty years ago I bought two core memory planes (1960's, $6K new) for $50 each. Gave one to my dad, kept the other. Astonished these hadn't inflated like art work.
- TedDoesntTalk 6y agoFor the same reason technology from the early 1900s has little artistic value... most people don’t appreciate it. Having said that, I have a nice 1960s pay phone on display and a LC Smith typewriter from the 1920s also on display. My children don’t even know what they are.
- kens 6y agoProbably because core memory was so ubiquitous in the 1960s and early 1970s, so there's a lot of supply. Almost every computer used core memory and each memory module had a stack of planes. IBM was producing literally billions of ferrite cores per year. (Of course that's not as impressive now when a gigabyte costs a few dollars.)
- m463 6y agoI wonder how many of these survived though? I wonder if there could be a somewhere like cuba - sort of a lost kindgom of 50's cars.
- kens 6y agoThere are a fair number of core memory planes floating around, both on eBay and with people I know. They were compact and made nice souvenirs when computers were scrapped, so a lot of people held onto them. As far as "lost kingdom", I've seen a bunch of core planes from Russia recently; they probably kept them in service longer.
- Stratoscope 6y agoCore memory is a beautiful thing. Here's a four kilobit (64x64) plane I bought some years ago: https://geary.smugmug.com/Computers/History/i-jb2rgF5/A https://geary.smugmug.com/Computers/History/i-jb2rgF5/A Click the image to zoom in and see the detail of these (I think hand-woven) cores.
- m463 6y agoThese old school chips were amazing. I recently watched this old mainframe chip disassmbly: https://youtu.be/xQ3oJlt4GrI https://youtu.be/xQ3oJlt4GrI
- userbinator 6y agoFYI your link to "Design of Monolithic Circuit Chips" is broken.
- kens 6y agoThanks, I've fixed the link: http://doi.org/10.1147/rd.105.0370 http://doi.org/10.1147/rd.105.0370 (paywalled unfortunately)
- GizmoSwan 6y agoSurprisingly clear circuitry, and a nice looking paper weight too. IBM and made in France! I guess they made some chips in France. I hope that you would restore the paperweight. I was so intrigued that I looked for it on ebay with no luck.
- kens 6y agoWhat do you mean by restore?
- GizmoSwan 6y agoWeren't the chips removed from the paper weight?
- kens 6y agoNo, I looked at the chips under the microscope while they were still inside the paperweight. It wasn't easy but it worked.
- GizmoSwan 6y agoGood happy to hear that. It is very nice looking. You should frame it as an object somehow and add your analysis on the back of the frame. it would be worth a lot eventually in my opinion because your analysis identifies the components.
- peter_d_sherman 6y ago>"The Model 145 is notable as IBM's first computer that used semiconductor main memory. The computer is very large by modern standards, filling the blue cabinets below. One cabinet holds the CPU while another holds 256 kilobytes of memory chips. This computer predates the microprocessor, so the CPU is built gate-by-gate from many boards of integrated circuits. The Model 145 weighed over a ton, cost $5 to 10 million (in current dollars), and was roughly as fast as an IBM PC (1981)."