[HN Gopher] IBM paperweight teardown: Reverse-engineering 1970s ...
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IBM paperweight teardown: Reverse-engineering 1970s memory chips
Author : parsecs
Score : 56 points
Date : 2021-01-30 17:41 UTC (5 hours ago)
(HTM) web link (www.righto.com)
(TXT) w3m dump (www.righto.com)
| Syzygies wrote:
| Twenty 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.
| mhh__ wrote:
| If you can get someone to say it's art then it's art.
|
| I have seen a piece of fibre optic cable cut in half proudly
| displayed in an art gallery (fairly prominently even).
| Ultimately the people who appraise this kind of stuff have no
| idea what it actually does or how it works, if you want to be
| accepted you have to speak the right shibboleths.
|
| There are some artists that have an extremely good handle on
| what computers mean for the world, but I'm not aware of many
| that would fawn over a die shot like we would probably do.
| Stratoscope wrote:
| Core 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
|
| Click the image to zoom in and see the detail of these (I think
| hand-woven) cores.
| TedDoesntTalk wrote:
| For 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 wrote:
| Probably 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.)
| pasabagi wrote:
| To be fair, art work typically doesn't inflate much either.
| Unless you're very successful, it deflates almost instantly as
| soon as the exhibition is over.
|
| I once had somebody break into my cellar and steal an
| installation I'd built (a whole ton of handmade motors) for the
| scrap value.
| kens wrote:
| Author here: anyone else have interesting IBM artifacts to
| discuss?
| gnunez wrote:
| Thanks for your work Ken. I am learning so much from you.
| epc wrote:
| I 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).
| colejohnson66 wrote:
| Those 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
| codemac wrote:
| $$$$$$$$$
|
| 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 wrote:
| I'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
|
| 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.
| parsecs wrote:
| That animation is very, very informative. Thank you for
| your blogs and stuff like this!
| Johnny555 wrote:
| It'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)
| joezydeco wrote:
| @kenshirriff has an IBM "Technology Sample Kit" circa 1986 that
| looks pretty interesting:
|
| https://twitter.com/kenshirriff/status/1346517181098409985
| kens wrote:
| That's me! kens == @kenshirriff
|
| The technology sample kit was discussed on HN last week:
| https://news.ycombinator.com/item?id=25893087
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