Thalia Archibald

Computer science PhD student at the University of Utah, researching compiler verification with [@regehr](https://mastodon.social/@regehr ).
UNIX historian and archivist.
Occasional Rust standard library contributor.

Site: https://thalia.dev
GitHub: https://github.com/thaliaarchi

Public Key

npub1thrmps439tzkcx72uft5deu389rt39pdjxy6uvdrfw035t0jcrdsulw4nm

NIP-05 Address

[email protected]

Profile Code

nprofile1qqs9m3asc2cj43tvr09wy46xu7gnj34cjskerzdwxx35h8c69hevpkcpz3mhxue69uhhyetvv9ujuerpd46hxtnfduqs6amnwvaz7tmwdaejumr0dshrnnz0

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Author Public Key

npub1thrmps439tzkcx72uft5deu389rt39pdjxy6uvdrfw035t0jcrdsulw4nm

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Last Notes

2026-08-27 07:52:28 GMT

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I don't have a terminal that could do this. If I implemented that in the kernel, I'd need to grow the buffer from storing a single line to a page (though the kernel currently has no concept of pages of text). If I implement it in user space, I may as well just implement the more traditional arrow keys cycling through the shell history.

2026-08-27 06:19:00 GMT

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Just modified the UNIX V4 kernel and utilities so it supports backspace for deleting characters. Pressing backspace instead of # was the top mistake made by LRC attendees, so this would make it easier to use for modern users.
The erase (delete last character) and kill (clear current line) characters were fixed to # and @, inherited from Multics, and not made configurable until a few months later around November 1974. Perhaps this change reflects the first time a video terminal was used for UNIX.
I made it send BS SP BS when backspace is pressed to visually clear the character, but this unfortunately makes it clear commands' output too. For example, this lets you visually clear the shell prompt. I could fix this by implementing something like curses, but that would move the logic to user space and incur overhead for swapping the process for a context switch on every character press. This was a complaint of early vi. Maybe I could track the column of the last printed text and not let you visually backspace before that?
#unix #retrocomputing

2026-08-27 01:42:06 GMT

I fixed a little bug in UNIX V4 that had been bugging me. It took a terminal session of 5596 lines, including all the code I read, to arrive at a 4-line fix. Imagine all the paper.
https://github.com/thaliaarchi/unix-v4-demo/commit/33f294afb9cb48cda9ddbcb159d947d94c4eddd3
#unix #retrocomputing #vintagecomputing

2026-05-19 19:29:06 GMT

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Reply from [@zerodogg](https://hachyderm.io/@zerodogg ): "I love learning about UNIX history! Just got my physical copy of «a quarter century» in the mail (and for some reason no one I know are super-excited about this)."
Sadly Peter Salus passed away on Friday. It's an incredible book and a tragic loss :(.
https://www.tuhs.org/pipermail/tuhs/2026-May/033750.html

2026-05-19 07:21:33 GMT

This Friday, I will be speaking about UNIX V4 for @npub1j8e…ncgu'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.
#unix #retrocomputing #vintagecomputing
https://fd.discuss.systems/media_attachments/files/116/600/025/622/662/727/original/45a5d453edfc4bde.jpg

2026-04-25 05:44:06 GMT

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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 @npub1zyz…tpl5 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
https://fd.discuss.systems/media_attachments/files/116/463/719/425/779/229/original/7b582b0c5673579a.png

2026-04-24 06:39:49 GMT

A new UNIX snapshot from 1977 to be released soon!!!
#unix #retrocomputing #vintagecomputing

2026-04-17 01:16:48 GMT

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So you have all 19 or so cabinets? No wonder it's not all on display.
Is it just a regular Selectric?

2026-04-17 00:35:48 GMT

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
https://fd.discuss.systems/media_attachments/files/116/417/240/003/200/417/original/e129f88a08084c33.jpeg

2026-04-16 22:15:03 GMT

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A better view of the IBM 7030 operator console:
https://fd.discuss.systems/media_attachments/files/116/416/685/380/918/655/original/a59fb3e287f4bffb.jpeg

2026-04-16 19:45:23 GMT

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I learned of this model's significance from a little call-out in Peter Salus' excellent history of UNIX: "The IBM 7030, incidentally, had 64-bit words and 8-bit bytes."
https://archive.org/details/aquartercenturyofunixpeterh.salus_201910/page/n31/mode/2up

2026-04-16 19:42:18 GMT

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A CDC 6600 supercomputer with its wiring exposed, next to the IBM 7030:
https://fd.discuss.systems/media_attachments/files/116/416/087/446/418/870/original/d9d9ecf46b74915c.jpeg
https://fd.discuss.systems/media_attachments/files/116/416/671/585/353/587/original/9729d6fac39a84c1.jpeg

2026-04-16 19:38:56 GMT

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The BYU property tags on the IBM 7030 at the Computer History Museum.
#retrocomputing #vintagecomputing
https://fd.discuss.systems/media_attachments/files/116/416/072/398/544/030/original/e55ac33e141c8a2a.jpeg
https://fd.discuss.systems/media_attachments/files/116/416/072/541/258/498/original/2aba09bffb3bfaf7.jpeg
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https://fd.discuss.systems/media_attachments/files/116/416/072/750/319/970/original/320f2b3918dbad74.jpeg

2026-04-16 19:35:07 GMT

Utah computer history: This IBM 7030 at the Computer History Museum is from the BYU physics department, used from 1972 to 1982. It features a 64-bit processor, well ahead of its time at its 1961 release, and was IBM's first transistorized computer. Only 9 were made. Before this machine's use at BYU, it was used at MITRE Corporation from 1962.
Visited and photos dated 2025-12-20.
#retrocomputing #vintagecomputing
https://fd.discuss.systems/media_attachments/files/116/416/053/447/210/324/original/5ca11d0fd01d9872.jpeg

2026-04-12 18:36:12 GMT

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I need to solder up a DB-25 adapter that wires modem DTR (Data Terminal Ready) to terminal DTR and CD (Carrier Detect). Right now, I just use a jumper and it failed to work during my demo.

2026-04-11 00:01:17 GMT

My CoCo 3 works again! After hauling it across town to troubleshoot, it inexplicably fixed itself.
It was having signal issues. When connected to my Tandy CM-8 over RGB, it would only display with the second ground pin (pin 2) disconnected, but with a loud buzzing tone. It had this same buzzing when connected to my Portavision CRT over RF. But it worked just fine with my Commodore 1702 over composite. I didn't want to deal with this during my demo, so borrowed JJ's Magnavox CM8562.
When I returned his CM8562 today, I brought along my CoCo and CM-8 to troubleshoot. But when connected them, all the issues were gone! It was able to simultaneously display over RGB, composite, and RF without issues. He suspects the issue was static from the CRT interfering with the computer.
This is the opposite of the demo effect.
#retrocomputing #vintagecomputing
https://fd.discuss.systems/media_attachments/files/116/383/023/753/887/252/original/707d45db8ae4e0e0.jpeg

2026-04-04 01:18:13 GMT

BIOS on campus:
https://fd.discuss.systems/media_attachments/files/116/343/795/554/866/814/original/73b0832d0279bc77.jpeg

2026-04-03 21:39:46 GMT

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Please send help; I keep buying teletypes

2026-03-27 04:35:46 GMT

Anything that can go wrong in a demo will go wrong.
I couldn’t connect to the projector and used a TV. My serial pin jumper hack for my Teletype Model 43 didn’t work. My VT220 wouldn’t connect. My PiDP-11 fell, so all four standoffs are snapped with plastic stuck in the case. My Portavision TV wouldn’t tune to channel 3, so my three earliest CoCos were unusable. All my Commodore 64 games on floppies were unusable, because I couldn’t find its serial cable.
I’ve troubleshoot all of these things before and have detailed notes, but am utterly incapable when frazzled.
#retrocomputing #vintagecomputing

2026-03-26 10:02:17 GMT

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I got my first 43 connected to UNIX V7! I needed to jumper the Pi's Data Terminal Ready (pin 20) to the 43's Carrier Detect (pin 8). 43s switch from DATA (online) to TERM READY (offline, but ready) after about 20 seconds of CR being off and CR isn't one of the pins produced via DE-9, so it was only ever online for 20 seconds, unless I'd repeatedly press DATA.

2026-03-26 03:07:07 GMT

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Thanks for the help. After lots of reading (UNIX driver sources and manpages, DEC manuals, SIMH sources and docs), I've got my VT220, 703, and the emulated VT52 hooked up simultaneously to UNIX V7 over DC11! Still working on my 43s and 733 and UNIX V4. I'll have to polish a writeup when I'm done.

2026-03-22 19:02:15 GMT

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You've connected your terminals to modern machines, right? What setup do you use on the Linux side for your 707 (or other RS-232 terminals)?

2026-03-22 18:24:50 GMT

It's serial debugging day!
I need to get at least one of these teletypes working over RS-232 with UNIX V4 and V7 in SIMH. The SIMH docs are notoriously bad. Help would be appreciated.
#retrocomputing #vintagecomputing
https://fd.discuss.systems/media_attachments/files/116/274/215/302/119/904/original/0091af9fa934595d.jpeg

2026-03-18 19:28:09 GMT

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Sandworms (white lined sphinx moths) crawling around the vast expanse of dunes in Death Valley:
https://fd.discuss.systems/media_attachments/files/116/251/793/785/086/316/original/0e9bc76c694bb419.jpeg
https://fd.discuss.systems/media_attachments/files/116/251/802/108/350/120/original/27427e731df2e732.jpeg

2026-03-18 19:15:21 GMT

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Vibrant colors at Artists Palette in Death Valley:
https://fd.discuss.systems/media_attachments/files/116/251/773/098/216/966/original/ef2f7a314fc7bb3e.jpeg

2026-03-18 19:12:49 GMT

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Yellow (and purple) flowers blooming overlooking Badwater Basin in Death Valley:
https://fd.discuss.systems/media_attachments/files/116/251/758/247/002/578/original/358457159eae2ad1.jpeg
https://fd.discuss.systems/media_attachments/files/116/251/758/427/052/837/original/e52c190b643019be.jpeg
https://fd.discuss.systems/media_attachments/files/116/251/758/620/768/371/original/ff3258861011666c.jpeg
https://fd.discuss.systems/media_attachments/files/116/251/758/845/839/880/original/517572444a1af01b.jpeg

2026-03-18 19:08:37 GMT

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Yellow flowers blooming near Badwater Basin in Death Valley:
https://fd.discuss.systems/media_attachments/files/116/251/721/280/796/886/original/c3966c7ac24c9e3c.jpeg
https://fd.discuss.systems/media_attachments/files/116/251/721/541/750/227/original/24b7f1531489607c.jpeg

2026-03-18 18:58:39 GMT

Chilling at Death Valley to see the rare superbloom!
https://fd.discuss.systems/media_attachments/files/116/251/692/708/063/773/original/28fc5a99d7d8348b.jpeg

2026-03-10 17:14:29 GMT

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I never used Gmail and de-Googled long ago, so haven't used either of those services. But notmuch sounds nice and Rust is always good.

2026-03-10 17:02:18 GMT

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But just imagine … a mailreader that lets you read mail on a teleprinter … a better world is possible

2026-03-10 16:59:36 GMT

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I’m on many fun mailing lists, though. And I get eBay search notifications like the cheap Silent 700 707 teleprinter I snagged yesterday.

2026-03-09 22:11:11 GMT

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I'm looking for paper for my 703, 733, and 43. What paper do you use for your 707? I've seen 8.5" and 8.3" (A4) wide, various diameters, and various core diameters.

2026-03-08 00:07:57 GMT

Working on repairing my Macintosh SE. The disk drive seems to have dislodged and the speaker doesn't work.
#retrocomputing #vintagecomputing
https://fd.discuss.systems/media_attachments/files/116/190/632/575/613/042/original/87e78d6f6e59a613.jpeg
https://fd.discuss.systems/media_attachments/files/116/190/632/576/893/055/original/2cab3a66ade203cf.jpeg
https://fd.discuss.systems/media_attachments/files/116/190/632/618/027/841/original/ab5e170c5e6fb447.jpeg

2026-02-23 06:45:12 GMT

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Just revisiting this project now and that did the trick! The print head now moves smoothly and quickly returns to home. It still doesn't print, though. It's probably the old thermal paper, but I haven't found somewhere selling the proper size.

2026-02-14 07:32:41 GMT

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Teletype Model 37 art. It’s ASCII68, but with half-forward and half-reverse line feeds, red and black, and an alternate character set with Shift In / Shift Out.

2026-02-11 03:59:39 GMT

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had to deal with the fallout of this: https://social.sdf.org/@elb/114889457430843982

2026-02-11 03:58:59 GMT

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Well that's a disaster! If they absolutely need to be taken down, they need to be archived first. If you point me to where, I'll start a recursive archive for the Internet Archive. That's still not ideal, as it would become even more inaccessible, but it would preserve from destruction.

2026-02-10 17:32:22 GMT

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Great UNIX collection!

2026-01-29 18:23:03 GMT

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Ironic.

2026-01-28 23:59:11 GMT

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I had the pleasure of playing Spacewar! and singing Christmas carols with the PDP-1 at the Computer History Museum last month. And Peter Sampson, who wrote the Harmony Compiler demonstrated his pioneering computer music work. Very fun!

2026-01-28 21:40:05 GMT

Fortunately all my vintage tech still fits in a corner! I have to specialize in little computers and teletypes now.
#retrocomputing #vintagecomputing
https://fd.discuss.systems/media_attachments/files/115/974/879/827/704/499/original/90e67083d9f6fb4d.jpeg

2026-01-28 02:52:23 GMT

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That's the one you talked about in "The Basement" playing with at coffee shops! It's got such a tiny screen, haha.

2026-01-28 02:50:54 GMT

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So the 703 already has a DB-25 connector and would need an external modem to connect to a remote device. Its twin model, the 707, has acoustic coupler, wall, and phone connectors and has an internal modem. I picked the 703, because I wanted RS-232 without any extra hardware. I think you're talking about the 707?

2026-01-28 02:38:44 GMT

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I've started going after the smallest computers, until I have more space. I have a Silent 700 703 shipping, which I believe is the smallest teleprinter model. Also, I want a TRS-80 MC-10 (the smaller Color Computer precursor) and TRS-80 Model 100 or 102 (also small). Oh, and I already have a TRS-80 Pocket Computer 2. So many unrelated TRS-80 models!

2026-01-28 02:29:43 GMT

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I've just got little stuff, but you have several big irons!

2026-01-28 02:18:14 GMT

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I thought it was just PS/2, but it's a weird bus mouse, so I'd need to rig up a microcontroller to use it with a modern system. Feels like more work than its worth.

2026-01-27 22:51:34 GMT

Haul #3: Accessories!
Obsolete Tech / Dasher Deals in SLC is unfortunately closing at the end of this year, but for now they're liquidating vintage tech at great prices.
I picked up a VT220 virtual terminal, Commodore 1541 floppy drive, TRS-80 Pocket Computer 2, AlphaSmart Pro, C.ITOH Prowriter Jr. dot matrix printer, Logitech P7-3F mouse, C64 joysticks, CoCo books, and some ribbons.
Acquired 2026-01-16.
https://obsoletetech.us/
#retrocomputing #vintagecomputing #terminal
https://fd.discuss.systems/media_attachments/files/115/969/060/698/767/491/original/6b44def8647ccf71.jpeg

2026-01-26 19:41:22 GMT

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Thanks! This feels much more actionable.
I'm well familiar with the Teletype Model 37 manuals (the model I don't have and will never be able to get :( ) and they have great troubleshooting guides. I haven't found anything similar for the Silent 700s.

2026-01-26 18:45:07 GMT

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Testing the keys of my 733. The print head motor needs some help to move. Anyone in SLC want to troubleshoot together? I come from a software background, so am in a little over my head on this.
https://fd.discuss.systems/media_attachments/files/115/962/867/221/331/481/original/d6a1c11d0df17ba6.mp4

2026-01-26 18:41:47 GMT

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With the cassette ASR cover removed, showing the internals.
https://fd.discuss.systems/media_attachments/files/115/962/861/461/080/155/original/78669cffb0c53af9.jpeg

2026-01-26 18:40:14 GMT

Testing my teleprinters.
#retrocomputing #vintagecomputing #teletype
https://fd.discuss.systems/media_attachments/files/115/962/845/176/333/526/original/ee32c729108075dc.jpeg

2026-01-25 00:41:59 GMT

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The hackathons around here always seem to be organized around some inane AI theme. Though my undergrad did 24-hour hackathons that allowed you to build whatever you want, which were fun. But I'd love to do a retro hackathon.

2026-01-24 23:39:36 GMT

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Ah, you're using Tim_Shoppa_v6; I was hoping it was an original copy. Very cool you have the hardware to run this.

2026-01-24 23:11:15 GMT

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Very impressive collection!
You write that one of your disk packs has UNIX V6. Have you imaged this disk? There's a snapshot of V6 that I know of that's two months earlier than Dennis_v6 that I intend to release to TUHS soon. Yours could also be a unique snapshot.

2026-01-24 22:48:30 GMT

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The timeline sounds off on that. C was developed in 1972–1973, the Model 43 was introduced in 1977, and Model 37 in 1968. I watched that talk and recall him talking about a prank with reverse line feeds on a Model 37 at Research; are you thinking of that?

2026-01-24 22:42:53 GMT

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My white whale is a Teletype Model 37, but they're exceedingly rare. I'm interested in them for their popularity with early UNIX users and influence on roff and am sporadically working on an emulator. I've reached out to several people who have connections to these machines, to no luck :(.

2026-01-24 22:40:20 GMT

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My collection has been growing quickly, haha. Over the past two weeks, I've acquired a TI Silent 700 ASR 733, VT220, Tandy Color Computer 1, 2, and 3, Commodore 64, TRS-80 Pocket Computer 2, and a bunch of accessories. Photos to be posted soon.

2026-01-24 22:33:49 GMT

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I aspire to have an office as cool as this!

2026-01-18 23:29:14 GMT

Building my PiDP-11 (from https://obsolescence.dev/) and hacking on UNIX V5 with ed. It's an incredibly productive system! Little did I know, we'd shortly find a version of UNIX V4 from nine months earlier.
On screen is a Whitespace interpreter I was working on for V5—my project whenever I learn a new language (https://github.com/wspace/corpus).
Photos dated 2025-04-06 and 2025-04-23.
https://fd.discuss.systems/media_attachments/files/115/918/658/479/023/181/original/d786002eab3dbc5b.jpeg
https://fd.discuss.systems/media_attachments/files/115/918/658/495/406/994/original/0700639bdc17351c.jpeg