Posts by thalia@discuss.systems
(DIR) Post #B5IxoGlAMLos0L13bs by thalia@discuss.systems
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ASTRONAUT: PLEASE CRANK THE SILLY THING AROUNDOFF TO SEE THE WIZARD...#retrocomputing #vintagecomputing #nasa #apollo #artemis
(DIR) Post #B5IxoGxZcDkCcooxwu by thalia@discuss.systems
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TEMPORARY, I HOPE HOPE HOPE#retrocomputing #vintagecomputing #nasa #apollo #artemis
(DIR) Post #B5NUDtFAO9t7lV9IVk by thalia@discuss.systems
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I now have my own Utah teapot!This ordinary teapot is the "hello world" object of computer graphics and has cameos in countless productions.A thread on teapots and UNIX… 🧵Photo: My Melitta teapot, 2026-04-16.#retrocomputing #vintagecomputing #unix #utah
(DIR) Post #B5NUDthWgiZbBSPwiO by thalia@discuss.systems
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@dougmerritt I'm still looking for a Blinn-ratio Utah teapot, that they produced for a short while!
(DIR) Post #B5NUDvnGuKMDfr7Ywq by thalia@discuss.systems
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While working on his 1975 dissertation on procedural modeling at the University of Utah, Martin Newell needed a good test object and, at the suggestion of his wife, picked their Melitta tea set. He measured it by hand and created a model rendered with Bézier curves, one of the first to be modeled as rules instead of a set of points.Shortly thereafter, Jim Blinn refined the model. While doing a demo, he shrunk the model vertically by a third, but everyone liked it better that way, so it stuck. His 1977 publication with Martin on texture and reflection applied several fun textures to the teapot and from there its popularity spread.Photo: A Utah teapot in the Kahlert School of Computing office, signed in 2023 by Martin Newell and Jim Blinn, 2025-11-07.#retrocomputing #vintagecomputing #unix #utah
(DIR) Post #B5NUDwgDc2JGQGpRaq by thalia@discuss.systems
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At the same time as he modeled the teapot, in 1974, Martin acquired a copy of UNIX V4 for the new computer graphics lab he was managing. It was evidently to serve as the operating system for the lab's PDP-11/45 computer. But UNIX had only been publicly released a few months prior and was still quite flakey, so it went unused, in favor of DEC's more conventional DOS and RSX-11M operating systems.Photo: UNIX V4 tape with the original Utah teapot at the Computer History Museum, held by Jon Duerig and Thalia Archibald, 2025-12-19.#retrocomputing #vintagecomputing #unix #utah
(DIR) Post #B5NUDxci6Z67LgC9lQ by thalia@discuss.systems
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After the obsolescence of minicomputers, the UNIX V4 magnetic tape was saved from destruction by Jay Lepreau, an operating systems researcher involved with USENIX conferences. But, without any way to use it, it sat in his office until last July, when Aleks Maricq discovered it while preparing to move the Flux research group to the new building.I heard the news just after Rob Ricci (@ricci) posted and was soon holding the tape. But without any accompanying documentation, its background was a complete mystery. The University of Utah was not known to have been involved with UNIX, "only" computer graphics and the ARPANET, so I had to go back to primary sources. I tracked down lists of early UNIX users and found Martin's name listed among about 25 sites using UNIX V4. Through numerous hours in online and physical archives, I found that UNIX was not used for research at the U until later, corroborating Martin and Jim's recollections. But, being at the cutting edge, they followed the latest technologies.Photo: Researchers holding the UNIX V4 tape in the storage closet it was found, left to right: Thalia Archibald, Aleks Maricq, Jon Duerig, Rob Ricci, and Axel Sorenson, credit: Dan Hixson, 2025-11-12.#retrocomputing #vintagecomputing #unix #utah
(DIR) Post #B5NUDyYUdjJoEtEIpU by thalia@discuss.systems
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As the only surviving copy of this version of UNIX, it was vital that it be preserved. Jon Duerig and I brought it to the Computer History Museum's Research Archives, where vintage media recovery has been honed over decades. There, Al Kossow (@bitsavers) recovered the raw analog waveform using his modified tape drive, explaining the process to news and museum film crews as he worked. By recording the low-level waveform, it can be analyzed offline without stressing the tape by reading it again. This was done with Len Shustek's readtape program and, after some debugging with Len, we recovered a complete, flawless dump. Fortunately, the tape was in impeccable condition and did not need to be baked.Photo: UNIX V4 tape with Al Kossow's Utah teapot in the CHM Archives lab, 2025-12-19.#retrocomputing #vintagecomputing #unix #utah
(DIR) Post #B5NUDzR5MkzGyCltvE by thalia@discuss.systems
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A quick, preliminary analysis of the disk image before sharing showed it was a unique snapshot, earlier than V5. We could see Hunt the Wumpus, SNOBOL, and an older version of cc. Then within hours of my tape image upload to the Internet Archive, Angelo Papenhoff (@aap) produced a working SIMH emulation setup and published instructions. Within days, Jacob Ritorto had booted it on a real PDP-11/45 and Ashlin Inwood on a PDP-11/40, the two officially supported machines. And I visited the Interim Computer Museum (@icm) to attempt booting on their "misspiggy" PDP-11/70, but more repairs were needed.As a historical artifact, the UNIX V4 tape fills in a midpoint of a 19-month gap in UNIX source code. It was shortly after the kernel was rewritten from assembly into C and was rapidly growing into a system we recognize today. And at the University of Utah, it adds a connection in a history of pioneering computer science research, and I'm happy to have been involved.Photo: UNIX V4 tape with a PDP-11/20 and UNIX V1 manual at the Computer History Museum, held by Jon Duerig and Thalia Archibald, 2025-12-19.#retrocomputing #vintagecomputing #unix #utah
(DIR) Post #B5etAzU2X7KYn48fSq by thalia@discuss.systems
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A new UNIX snapshot from 1977 to be released soon!!!#unix #retrocomputing #vintagecomputing
(DIR) Post #B5etAzivdlExXF6Yfg by thalia@discuss.systems
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We've recovered another UNIX distribution that hasn't been seen in almost 50 years!This is UNIX Program Generic Issue 3 from 1977-04-12. It descends from V6 and evolved into System III. We thought it didn't survive, but it turned up in some tapes @bitsavers read yesterday!You can run it in SIMH with scripts I wrote, browse the sources in the Unix Tree (thanks Warren!) or from a tar, or read the Program Generic documentation (thanks Matt!).https://www.tuhs.org/pipermail/tuhs/2026-April/033605.html#unix #retrocomputing #vintagecomputing
(DIR) Post #B5hlMA11V1ZMTtGHA0 by thalia@discuss.systems
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@alina Do it! GRUB is bloated. I wrote most of a not-compliant-with-anything bootloader last year.
(DIR) Post #B697Y2NBBUGaVpbxnE by thalia@discuss.systems
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A cursed feature of C in 1972: Labels and functions were reassignable (i.e., lvalues)!For example, this is a clever way to initialize once: goto init;init: ouptr = oubuf; init = init1;init1:which is compiled to:jmp *4120mov 4136,4144mov 4122,4120Note the indirect jump and assignment to that address. All gotos used indirect jumps. This apparently would have also worked with functions.#c #unix #retrocomputing #vintagecomputing
(DIR) Post #B697Y53nC1XcqZZ1UW by thalia@discuss.systems
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At the time, C was rapidly evolving into what we recognize today.It started as B, an untyped and interpreted language that only had one kind of value, a word. This was a perfect fit for the PDP-7 that UNIX started on, with 18-bit words, but as they transitioned to the PDP-11, with 16-bit words and 8-bit addressing, this became a limitation.Soon, types were added, to distinguish char, int, and pointers, and it became known as NB ("New B"). But, B wasn't particularly fast, as it was interpreted (well, threaded).Once it was rewritten to be compiled, the language became known as C (perhaps initially as NC). For a short while, everything in C was an lvalue like B, giving the above snippet, but this was dropped a few months later, presumably for efficiency.Some UNIX utilities had been written in B/C from the start, but efforts to rewrite the kernel itself in B/C had failed. Finally, once structs were added to C, it was powerful enough to support the kernel and it was rewritten in C over the summer of 1973, culminating in the release of UNIX V4.#c #unix #retrocomputing #vintagecomputing
(DIR) Post #B697Y63pTNAHwyaZBg by thalia@discuss.systems
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This snippet appears in cvft, a compiler for translating Fortran threaded code to machine code from June 1972, which is notably derived from the early C code generator. See putchar (and also getcha) in dmr/cgd/cvft.c.The earliest extant C compiler is last1120c from July 1972, the last C version for the PDP-11/20, before they migrated to the PDP-11/45. This version still has the label lvalue behavior of B seen in cvft. Then, it was changed to the modern behavior by the time of prestruct-c from December 1972. That version supports structures, but does not yet use them itself.All three can be found in Dennis_Tapes: https://www.tuhs.org/Archive/Applications/Dennis_Tapes
(DIR) Post #B6B6zXxI9rqoe0ya3M by thalia@discuss.systems
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Another strange pattern from the same program.This one reassigns the address of an array, `int nlist[250]`, in char increments. Arrays are no longer lvalues, so this doesn't work anymore. Also, the address is unaligned every other iteration.lbp;nlist[250];getnam(){ extern nlist, lbp; char nlist[], lbp[], c;loop: c = *lbp++; if (c==';' | c=='\n') goto el; *nlist++ = c; goto loop;el: *nlist++ = '\0';}Somewhat simplified from Dennis_Tapes/dmr/cgd/cg1.c:getnam.
(DIR) Post #B6B6zYrIncebRjBJM8 by thalia@discuss.systems
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This snippet deliberately triggers a "Bus error -- Core dumped":int o1[];o1 = -3;*o1;From Dennis_Tapes/dmr/cgd/cg1.c:expr.
(DIR) Post #B6SZYEhJqkltSP9Z5s by thalia@discuss.systems
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This Friday at noon PDT, I will be speaking about UNIX V4 for @lindsey's Languages, Systems, and Data Seminar! I'm excited to demonstrate programming with a teletype, as that hasn't fit into my other talks.If you're interested, email (see my site) or DM me for a Zoom invite.Abstract: We recently recovered UNIX V4 from a 1974 magnetic tape at the University of Utah. This version of the UNIX operating system, thought to have been lost, was the 19th copy distributed to the public, just months after the first public announcement. It was originally acquired by Martin Newell while managing the computer graphics laboratory, and it was likely connected to his foundational research in procedural modeling and the famous Utah teapot. UNIX V4 was the culmination of the effort to rewrite the kernel in C, made possible by the introduction of structs to the language, and has shaped all modern operating systems. In this talk, I put this artifact into context within the larger history of UNIX and demonstrate period-appropriate software development with a paper-printing teletype and replica PDP-11.https://lsd.ucsc.edu/lsd-seminar/2026sp/#may-22#unix #retrocomputing #vintagecomputing
(DIR) Post #B6SZYF1Wdcw0T4bhaa by thalia@discuss.systems
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@ed1conf I will be demonstrating the standard text editor with a teletype :).
(DIR) Post #B6rtQyLVa5mE78VvGK by thalia@discuss.systems
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Of teapots and UNIX:#unix #retrocomputing #vintagecomputing