Tom Stepleton
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stepleton.bsky.social
Tom Stepleton
@stepleton.bsky.social
1.6K followers 89 following 110 posts
AI research engineer, glider pilot. Apple Lisa power user. @stepleton@oldbytes.space on Mastodon. Most of my posts will be about old computers; occasionally I'll mention flying.
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stepleton.bsky.social
Just in time for #PERQtober ! An adapter to replace your missing or broken #PERQ T2 landscape monitor with a VGA display: codeberg.org/stepleton/pe... Thanks to @skeezicsb@oldbytes.space for early advice.
A circuit board with two DIP ICs and some passive components connects a VGA cable and two DIN-5 cables (top) to a DIN-4 cable, a DA-15-terminated ribbon cable, and a 75-ohm coaxial cable (bottom). The bottom cables go to a PERQ T2 workstation; the top cables go to mouse, keyboard, and display.
September 29, 2025 at 10:24 PM
stepleton.bsky.social
The Olivetti Programma P203 (1967) uses a circuit construction technique known as "transistor jail"
(or "cordwood" [1]. Seen at [2].)

[1] en.wikipedia.org/wiki/Printed...
[2] www.thecomputerchurch.org
August 26, 2025 at 3:24 AM
stepleton.bsky.social
Wheeling Airglow (en.wikipedia.org/wiki/Airglow... ) out to the runway at the British Human Powered Flying Club's 2025 Icarus Cup event, Lasham Airfield, Hampshire.
A group of people walk a slender aircraft with long wings down a tarmac taxiway, all silhouetted by the rising sun ahead of them. A shallow mist rises off of the airfield's grass surface.
June 20, 2025 at 8:04 PM
stepleton.bsky.social
Happy Pride #rc2014
An assembled RC2014 Zed Pro modular Z80 hobby computer, which comprises a backplane about the size of a paperback book with playing-card sized component circuit boards plugged into it vertically. This particular Zed Pro is the limited-edition Pride kit, where the component boards are coloured so that they form a rainbow when arranged in the backplane. The computer rests in the hands that assembled it, which here are sporting some fairly long, blue-varnished fingernails. All of the electronic components, including dozens of resistors, headers, and IC sockets, were placed and soldered with the fingers and fingernails shown.
June 4, 2025 at 12:04 AM
stepleton.bsky.social
#Smalltalk -80 on #PERQ --- Mario Wolczko's implementation (www.wolczko.com/st80/) running with maybe some gremlins still to sort out.
A monochrome graphical display from an old computer workstation. In a large window at the centre of the display, a Smalltalk-80 session can be seen, with a browser window partially occluded by a System Transcript and a System Workspace window.
May 20, 2025 at 12:12 AM
stepleton.bsky.social
#PERQ PNX 5.03 manual pages at mg-1.uk/pnxman/pnxma... . The most interesting ones don't render very well with my hacked copy of a roff-in-JS "typesetter", but some interesting nuggets are there to reward persistence.
PNX 5.03 manual pages
mg-1.uk
May 13, 2025 at 10:52 PM
stepleton.bsky.social
Grab your ear defenders, it's time to see the exciting features of 1986's PNX 5.03, the Unix for the #PERQ 2 workstation! Skip to 2:10 to bypass booting and go straight to the non-X11 graphics action!
www.youtube.com/watch?v=TZRo...
PNX 5.03 reboot and demonstration on a PERQ 2T2
YouTube video by stepleton
www.youtube.com
May 7, 2025 at 11:37 PM
stepleton.bsky.social
OK, so the #PERQ 2T2's disk system will work if:
* you let it warm up for a bit
* you have the logic analyser attached to U9 on the EIO board
* ...and running
Splayed out on a wooden floor: a covers off, partially-disembowled PERQ 2T2 under-desk workstation computer. Wires snaking out of the PERQ attach to a solderless breadboard which is then attached by a sheaf of probe leads to an old Tektronix logic analyser nearby. It looks a mess but atop it all is a 19" monitor showing video coming out of the PERQ. The machine is running and shows the diagnostic code 255 on a 7-segment display.
April 22, 2025 at 11:58 PM
stepleton.bsky.social
Say, would anyone like to answer a newbie's gpg question? security.stackexchange.com/questions/28...
March 22, 2025 at 12:18 AM
stepleton.bsky.social
The EC2 instance is terminated and the AWS account cancelled. The site no longer links to larger files on Google Drive. Continuing to pull away from larger tech firms...
March 10, 2025 at 12:25 AM
stepleton.bsky.social
This is pretty funny to, like, maybe three people on Earth.
Top, the Inmos logo: the word Inmos to the right of a black circle with a grid of white squares inside. It's meant to recall a silicon wafer full of integrated circuit dies. Inmos was a legendary British semiconductor manufacturer who invented the transputer architecture, an innovative also-ran. Bottom: the logo for Imo's Pizza (an infamous St. Louis chain) next to an image of a circular pizza cut into squares, as Imo's does.
February 25, 2025 at 11:18 PM
stepleton.bsky.social
If you transport something that sorted right, speak of a six one one member contact to see staff or police the sea. We'll sort on it. Doesn't say it, zero six it, look British.
February 23, 2025 at 11:43 AM
stepleton.bsky.social
Question for email self-hosters: what do you do with two email servers? Plenty of self-hosting docs say what to do with one, but what are some common small-site configurations for people who like two MX entries for their domain? It seems like it could make things more dependable, but in what form?
January 31, 2025 at 7:35 PM
stepleton.bsky.social
I post what from This is .
A fraudulent Jupiter ACE 4000 and Jupiter ACE 4000 manual: it's actually a regular Jupiter ACE in an ACE 4000 case. Both the ACE and the ACE 4000 were inexpensive, book-sized home computers that used the Forth programming language instead of BASIC. Forth uses a postfix (aka "reverse Polish") notation, which is the joke behind the strange word order in the post.
January 28, 2025 at 10:55 PM
stepleton.bsky.social
Had a Great Clown Pagliacci moment after searching "depraz mouse manual" and turning up www.tuhs.org/pipermail/tu...
[TUHS] Depraz/Logitech Digimouse manual
www.tuhs.org
January 4, 2025 at 2:58 PM
stepleton.bsky.social
After learning the true meaning of "we're not doing presents this Christmas", it was off to the makerspace to hastily laser-engrave and laser-cut jigsaw puzzles for everyone.
A parody clone of the cover of a Ravensburger puzzle box, advertising a "Laserburger Puzzle" with "up to 570" pieces and "Crummy Laserburger Qualtiy [sic]". The puzzle claims to have "Arduousclick Technology", referencing the "Softclick Technology" of actual Ravensburger puzzles. The puzzle itself appears to be a halftone image of a bunch of potatoes, and helpfully the original potato image appears at the bottom of the box art alongside the text "it is potates".
December 27, 2024 at 3:35 AM
stepleton.bsky.social
About a month ago I fixed the mouse on my circa-1983 #PERQ 2T2 computer: a key feature for an early graphical workstation. It was a wild troubleshooting journey --- in the end, there was nothing wrong with the mouse itself. You might not believe what it was...
An electronics workbench with a PERQ 2T2 computer resting atop it: its system unit is not quite as large as the kind of refrigerator that fits beneath a desk. Most of its covers are removed. Highlighted in the image is the PERQ's three-button mouse. Text on the image says, "Issue: mouse not functioning, other peripherals seem to work ok".
December 21, 2024 at 3:11 PM
stepleton.bsky.social
I'm running low on tractor-feed paper. There's barely enough to make this year's greeting cards!
Close-up of an Apple Lisa computer's display as the LisaDraw program sends a festive card design with a Christmas tree to a dot-matrix printer. The Lisa's print dialogue is verbose. It tells the user that print spooling is available: that is, the user can dismiss the dialogue and do other work while printing continues. But it also points out that if the user does this and then at some point "hear[s] a whistle", they should reopen the print dialogue. (The Lisa's "whistle" is a rising bloopy sound that the Lisa makes if printer trouble occurs, like running out of paper. I only know early versions of the Lisa Office System to make this sound.)
December 12, 2024 at 1:09 AM
stepleton.bsky.social
Proparoxytone! Obtained in pharmacies and restaurants. Measured in Jupiter's atmosphere; in the Indian but not Atlantic or Pacific oceans. Available in quantity, produced by electricity, also chemical processes and mystical rituals. Proparoxytone: it's not for you or me but it's right for everyone.
December 9, 2024 at 9:43 PM
stepleton.bsky.social
Fixing 40-year-old #PERQ computers eats notebooks! It was working, now it won't talk to the hard drive. After probing three interface boards on the bench, I now think the problem lies elsewhere...
A notebook with dense, tabular notes in fine writing is propped up by an oscilloscope resting atop a PERQ computer system unit. At the bottom, the PERQ's diagnostic numeric display reads 014, which means the computer couldn't boot from the hard disk.
November 25, 2024 at 12:44 AM
stepleton.bsky.social
Greetings new followers, I'm glad you're here! As a periodic reminder and despite my day job, this account remains essentially dedicated to OLD COMPUTERS and OLD COMPUTER ACCESSORIES.

Stay tuned for a thrilling post about dropout as it pertains inadvertently to executable code for a Z80 processor.
The cartoon character Hank Hill from the TV show King of the Hill gives a wary eye to a desktop PC with a CRT monitor perched atop.
November 11, 2024 at 6:10 PM
stepleton.bsky.social
It’s just turned November here — that wraps up #RetroChallenge 2024! I dedicated my month to reviving an early 1980s #PERQ 2T2 (en.wikipedia.org/wiki/PERQ) graphical workstation. Let me show you how far I got… 🧵
A PERQ 2T2 system unit with its covers off. The machine is operating and a 3-digit LED readout at top right says 999. Circuit boards with ribbon cables exiting are visible; so is a Gotek floppy drive emulator. At right, the PERQ keyboard (taking layout cues from the VT100 keyboard) and behind it a LCD monitor showing black text on a mostly-blank white background.
November 1, 2024 at 1:03 AM
stepleton.bsky.social
Hi new bsky followers --- so I did warn that this account mainly posts things about unusual old computers. Hang on because before long you'll see if this is the kind of thing you want in your timeline...
October 31, 2024 at 11:37 PM
stepleton.bsky.social
I appreciate folks following me who are interested in what I do at my day job! But posts you'll find from me are mainly about fixing+operating some really unusual old computers. If I do it right it may still be interesting...

I post a little bit more on Mastodon: oldbytes.space/@stepleton
A Tektronix 136-channel logic analyser with probe wires snaking over to a PERQ 2T2 graphical workstation with its covers off in the background. The PERQ is quite the repair challenge!
October 28, 2024 at 10:29 PM
stepleton.bsky.social
Folks, the #RetroChallenge #PERQ's video corruption is so weird: besides odd letterforms, it's invented new ligatures (en.wikipedia.org/wiki/Ligatur... ).`i` looks like `i|` and blanks part of the next letter. `y` or `y¦` does less blanking but NOT for the letter `o`, or `ϕ`. There are others!
A grid of letters on the PERQ 2T2 video display: odd columns count up through the alphabet of lower-case letters, while even columns are the same letter, which counts up through the alphabet on successive rows. For the alphabet `abc`, this would be: aabaca abbbcb acbccc The letters are corrupted in various ways, usually involving the addition or removal of vertical lines. Inset boxes show the corruption described in the post up close.
October 27, 2024 at 11:01 PM