How I Spent Maai Weekend

My friend Tim Schutz and his malfunctioning robot Maai came over for our third Robot Sunday last weekend. (Robot Sunday one, two.) We’re trying to restore the robot, a Heathkit HERO-1, to full 1980s lustre. Maai was wearing a kind of clown mask Tim made to replace its protective faceplate, and an elastic belt to keep its panels on. On boot, the robot said “Low voltage”. (This was to be a recurring motif.) Then Tim demoed adjusting the pitch and speed of Maai’s voice.


Last time, we hypothesized a couple of chips had to be replaced on the main sensor board. Tim had bought the chips for our proposed repair from Alphatronics USA in the Tukwila warehouse district near Seattle. Entering the store, he said, was like entering the twentieth century.

Concerned about the voltage, Tim checked it on the robot power supply: 5.3 volts, so probably OK.


The robot was plugged into the wall, because Tim didn’t charge it the night before; he left the robot in the car all night…


Bad robot, no chips. Well, OK, a couple – Tim yanked the sensor board, I replaced the analog-to-digital chip and one other, and Tim replaced the board.

It was now time for diagnostics, as many diagnostics as the galaxies in the sky. Fortunately, we had the arm and pendant (wired remote) this time, and Tim and I were both getting the gist of the diag routines through the sheer rotework of entering them in hexadecimal machine language over and over.


We got through the initial diags to the first sensor tests (motion sensors), but then once again, no response. The LEDs were supposed to light up on motion. (As we worked on Maai, the robot intermittently complained of low voltage. Aloud.)

The main sensor board had light and sound inputs, so we tried those tests next. The light sensor worked a little, but didn’t display a full range of response to bright light, dim light, and darkness. The sound sensors also seemed not as sensitive as expected. Batteries low again, maybe. We were seeing excellent voltage jumps on the board, though, from 0.x to 3.x to 5.x – dark to dim to bright. Was it just that the robot’s display was busted? There was no voltage when we made a loud noise during the sound test. Problems with the sensor board and sound receiver? Mic disconnected? Conclusion: Whatever it was, it wasn’t the chips we replaced after all.

Many other things were kind of working. Sonar was, but it was raining outside so we could only test it for short distances. The pendant seemed to be working. The motion sensor and display were actually working perfectly on second examination. (We had been looking at the wrong board for the motion test. When we found where the right one was tucked away, the motion LED was blinking cheerily.)

The voice synthesizer worked. Tim wanted to do a spoken haiku demo where the robot would spin around afterward, but the drive motors were not working. There were also mechanical problems with the arm as well as electronic ones. Tim is going to strip the arm’s corkscrew motor and other parts down and rebuild them himself. He schooled me in the mechanics of the arm and its claw, but there’s so much to do on this little guy, and we only meet once a month.


So what was wrong with Maai, at base? For one thing, the onboard battery might have needed charged, even though we had it hooked up to wall power the whole time. Some new capacitors couldn’t hurt, either. “They’re 30 years old. When they dry out, they tend to wreak havoc,” said Tim. He may replace the capacitors on the sense board before next time. (Moribund capacitors are a bane to all kinds of retrocomputers, from HERO robots like Maai to Apple IIs.)


We thought of some future improvements:

  • Maai doesn’t have a serial interface, but Tim has the schematics, so we could build one. That would enable saving robot software on an external medium like a thumb drive, and expedite diagnostics, among other tasks.
  • Rare earth magnets to hold the side panels on instead of an elastic belt.
  • Various new masks for the front faceplate area, such as creepy humanoid eyes.

Moral if you want one: Debugging is harder than coding, and repairing something is so much harder than building it from scratch.

See you next Robot Sunday.

Comments on the blog, please, not on Twitter or F*c*b**k.

The Time Cadet Keyboard


A few entries ago in this blog, I used a photo of the so-called Space Cadet Keyboard, the keyboard shipped with the famous Lisp machines of the 1980s. Depending largely on whether you are an Emacs user or a vi user, the Space Cadet Keyboard was either the most brilliant input device of all time, or the cause of everything that has gone wrong in any field of human endeavor under discussion.

That photo attracted lots of attention, for certain very, very wee values of “lots”. My friend John Braley remarked on F*c*b**k, “My new mantra: Hyper super meta – meta super hyper.[repeat]”, referring to the special modifier keys present on the Space Cadet but not most other keyboards – unlike Shift, Control, Alt, and so on. Of course, the Space Cadet wasn’t only long on modifier keys, but on Greek characters, math and logic keys, and keys of dubious utility – Roman numerals, friends?

I was (briefly) a computer science major at Yale in the mid-1980s, when this bizarre beastie flourished. I remember typing my APL homework on a similarly baroque keyboard – they were in all the labs – but I wouldn’t swear it was a Cadet. In fact, it was probably a descendant of the IBM 2741.


One thing I wanted to show in this post is that the Space Cadet was a lot more complicated than the first photo I included as a joke. As you can see up top, the keys are very tall – that is, high off the base – and they have room for even more characters on their fronts – the parts facing the user when she is facing the screen. (Closeup)

These characters can be Metaed, Supered, and Hypered until your carpal tunnel becomes inflamed. It says here that the Cadet could generate over 8,000 discrete characters. (Another large illustration.)

Space Cadets and Christianity (what?)

As an atheist, I am no friend of Madeleine L’Engle’s YA Christian propaganda A Wrinkle in Time and its four sequels, the “Time Quintet”. But I haven’t always been an atheist, and I’m pretty familiar with the books, especially the first two – I used to love them.

I’m sure that the Space Cadet Keyboard influenced the fourth book in the Time Quintet – Many Waters – just as I am that the board game Cosmic Encounter influenced William Sleator’s novel Interstellar Pig

Sandy stuffed another large bite of sandwich into his mouth, and left the warmth of the stove to wander to the far corner of the lab, where there was a not-quite-ordinary-looking computer. “How long has Dad had this gizmo here?”

“He put it in last week. Mother wasn’t particularly pleased.”

“Well, it is supposed to be her lab,” Sandy said.

“What’s he programming?” Dennys asked.

“He’s usually pretty good about explaining. Even though I don’t understand most of it. Tessering and red-shifting and space/time continuum and stuff.” Sandy stared at the keyboard, which had eight rather than the usual four ranks of keys. “Half of these symbols are Greek. I mean, literally Greek.”

Dennys, ramming the last of his sandwich into his mouth, peered over his twin’s shoulder. “Well, I more or less get the usual science signs. That looks like Hebrew, there, and that’s Cyrillic. I haven’t the faintest idea what these keys are for.”

Long story short, merely by typing into what I must refer to as the Magic Time Cadet Keyboard that they want to go somewhere warm and dry, the twins Sandy and Dennys are transported to the antediluvian Earth – the time of Noah himself – where they both fall in love with Noah’s forgotten daughter, and conclude that the people of Noah’s time are so unmentionably evil that it’s only right that God murder all of them. The Flood was good to the last drop!

Given its profound spiritual powers and the fact that it has not only math and Greek characters on the keys, but Hebrew and Cyrillic (what about Enochian?), I am forced to conclude that the Time Cadet Keyboard is to the Space Cadet Keyboard as the Space Cadet is to a random decrepit IBM Model M. The Time Cadet Keyboard is a must-have for the retrocomputing enthusiast who has everything. Five thumbs up!

I bet you didn’t think this post was going to swerve from the retrocomputing hobby to the history of board games to atheist apologetics, did you?

What do you think? And hey, how about leaving comments on this blog, rather than on Twitter or F*c*b**k or wherever else you found this link? Thanks.

Photo by Dave Fischer, Retro-Computing Society of RI (Own work) [CC BY-SA 3.0 ( or GFDL (], via Wikimedia Commons.

APL keyboard diagram By User:Rursus (APL-keybd.svg) [GFDL ( or CC-BY-SA-3.0 (], via Wikimedia Commons.

Robot Sunday, Sunday, Sunday


As described in an earlier post, I’m helping my friend Tim Schutz restore his antique Heathkit HERO robot, Maai. It’s like restoring a Mustang, but more interesting and less macho. We meet one Sunday a month.

My Pomeranian Humphrey loafed about while we were working on the robot, but our other Pom, Bridget, had to hide. The robot seemed to fall into her uncanny valley. Odd, because usually Humphrey is more susceptible to that effect, barking at weird cartoons on television. I guess everyone’s valley is different.

Because it had been a while, we decided to run Maai’s diagnostics from the top. The robot mostly passed, although Tim had left the arm at home, so we were less sure about those routines that required it.

We did find the motion sensors weren’t working. And then the vision and audio sensors weren’t either. What the hell? How could so many sensors go out at one time? Was the main sensor board malfunctioning, as we had thought once before?

I stepped through the diagnostic flowcharts in the technical manual, and Tim measured voltages with his meter. It developed there was nothing wrong with the sensors. The hidden problem was that the display board was malfunctioning. The sensors might have been working just fine, but we couldn’t see the results at all. We traced the problem to two chips on the display board, and Tim planned to order them online. Good thing, because all the motion sensor flowcharts had dead-ended in a box reading “Return to Heath Co. for service.”

Dear Mr. Heath,

We are sending you this robot for repair from the future, where it makes the phone in my pocket look like Richard Feynman. Yes, I said the phone in my pocket

Coffee by Tandy

Our international scavenger hunt challenge: “VIDEO: Program a Commodore 64 (or similar vintage) personal computer to turn on a coffee maker and brew you a cup when you type in the command, ‘Rise and shine!'”

A couple of weeks ago, as aide-de-camp, I helped my wife Marty’s team with their attempt to win GISHWHES (the Greatest International Scavenger Hunt the World Has Ever Seen), on a challenge that if judged successful should net them 80 points — pretty substantial.

Marty and I made a regulation 30-second video to prove we had done it. The index card at the beginning reads (so you don’t have to freeze it):



We connected an X10 Firecracker controller to my computer’s serial port, and plugged the coffee pot (“Mr. Coffee” to you) into an X10 TM751 wireless transceiver, which actually switched on the pot. In between, there were various cables and thin air.

I already had the Tandy 102, but I’m not a home automation junkie, even though I had some of this X10 junk left over from the turn of the millennium, so there were false starts. At the last minute, I realized I had a female serial cable and needed a male one, so Marty had to schlep through Fry’s while I was at work to make it right. She later remarked, “Buying a male-to-male gender-changing connector isn’t as exciting as it sounds.”

We also had to buy a cheap coffeemaker that could be turned on by simply plugging it in; the one we normally use has an extra button you have to press. The first one we tried, from a thrift store, wouldn’t power up at all. Marty googled the model and found out it was the subject of a factory recall for electrical faults. Lucky us! She cursed and ordered Mr. Coffee from Amazon. The Mister really doesn’t do the fine Magic Beans roast justice, but he was just what we needed otherwise.

Ken Pettit’s FIRE.BA X10 software for the Model 100/102 was also just about right; I only had to add a single line of BASIC to comply with the contest requirements:

18 IF SELECT$ = “Rise and shine!” THEN SELECT$ = “A1N”

Translated into English, this means that if I type “Rise and shine!” at the prompt on my computer, as I do in the video, the computer should tell the X10 interface to turn device A1 (in this case, the coffeemaker) on.

Apart from the missteps, and a couple of hours of research to prove to myself it was possible to do what we wanted in the allotted week, most things were almost plug’n’play. The bulk of the week was spent waiting for serial cables to arrive from Amazon. We shot the video in one take, but Marty had to edit the length for GISHWHES because it takes more than 30 seconds to make coffee.

Shoutouts to the TRS-80 Model 100 mailing list for helping keep my 102 running, and the Seattle Retro-Computing Society for general retroawesomosity (I wish I could have been at the big four-club summit last week).

Now for some joe…

p.s. This Wondermark parody of MAKE magazine says it best: “How to do it terribly — expensively — and with great difficulty”.

Tim’s HERO, Maai HERO


Spent the day running diagnostics on a 34-year-old Heathkit HERO 1 robot with my friend Tim Schutz. (It’s his robot.) At first this activity felt strangely like Raiders of the Lost Ark (“Behold! This primitive robot was built by the ancient Egyptians!”) but, partly because HERO looks a little like R2-D2 (small coincidence), everything morphed into that scene from Star Wars where Luke takes the droids out to his garage for repairs. We were actually punching in machine language routines on a hexadecimal keypad on the little guy’s head. I was expecting HERO to twitch at any minute and start projecting a hologram of Princess Leia. (Tim observed that if it did, Leia would be about 60.) Another difference from the cinematic original was that we were accompanied by two curious, fierce, and slightly alarmed Ewoks, my Pomeranians Humphrey and Bridget.

We determined the robot was in pretty good shape for being so old. The sensor board must be repaired, but the robot came laden with schematics, and in true Heathkit style, everything was labeled clearly. There was even a flowchart in the manual for the necessary fix. The wheel motors work, so the robot can move around, and the arm basically works, but the claw needs a bit of mechanical repair.

I said the robot was primitive, but really it reminded me of a larger version of a 21st-century LEGO Mindstorms robot, and I am filled with admiration for the Heathkit engineers, who made an interface breadboard available even after the head carapace goes back on. Very makery!

Tim named his robot Maai, a Japanese word he knew from Aikido that means “distance”, so its full name would be Maai HERO. Ironically, the distance sonar is the only sensor working right now.

Photo credit: Heathkit catalog circa 1979, via

How I built my first computer


Assembled FIGnition (right) shortly after boot (left, my Android tablet displaying documentation)

I just finished building a computer — a FIGnition single-board, 8-bit microcomputer kit. You can think of it as like the Heathkits of old, only about the size of a credit card and much resembling a Raspberry Pi.

There’s a bit of a paradox here. The Raspberry Pi costs about the same as a FIGnition — US $35 — and is meant for education. Yet it comes preassembled because it is literally about 10,000 times more complex than a FIGnition (five orders of magnitude). On the third hand that grows out of the center of my forehead, I love the Pi and have two of them. They are modern computers and the FIGnition is not — at least, it doesn’t feel like one.

Why did I buy a FIGnition, then? I wanted something I could build myself that was simple enough to understand thoroughly. The fact it boots into Forth also attracted me strongly — a FIGnition is probably the closest thing I can afford to a Jupiter Ace any time soon.

It took me, a complete newbie at through-hole printed circuit board soldering, six hours over two days to assemble the board with the expert advice and troubleshooting of my friend Tim Schutz. Half an hour was then devoted to a break, per the instructions, and an hour to testing by eye and with a multimeter. (Tim advised skipping the hundreds of complicated meter tests in the instructions and focusing on the basics — it’s only a $35 kit computer, after all.) Total build/rest/test time was 7.5 hours. If you’re already an electronics person, it will take much less for you.

After testing the unit, we plugged it into an old CRT TV and powered it on. The FIGnition welcome screen flashed by too fast to capture with a camera, then the Forth prompt. (See the photo above.)

We plinked around with the built-in chord keyboard for a minute and then, after Tim left, I ran most of the diagnostics — everything was OK. I didn’t take the last step, upgrading the firmware, because there hasn’t been a new firmware version since 2012, and I didn’t want to risk pointlessly bricking something I had just spent almost eight hours building.

I plan to keep working with this device and learning about it. The website has a great little knot of pages called “Understand It” that explains many of the hardware and software details. I also plan to extend my Forth skills — most of which come from cursory work with Jupiter Ace emulators, Wikireader, and Open Firmware — just because Forth is an interesting language, not because I ever expect to get a job programming in it. I’ll also blog about it in whatever time I have left over…

Discover lost (Geo)Cities with digital archeology


As I write this, Yahoo (I omit the exclamation mark because Yahoo bores me) is acquiring Tumblr for $1.1 billion, a move many are comparing to its 1999 acquisition of GeoCities — an arguably similar virtual community it subsequently neglected for a decade and then literally destroyed. Will the same be said of Tumblr’s 300-million-strong community in ten years? “We promise not to screw it up,” says Yahoo. Really. That’s what they said. I’m betting on the “condemned to repeat it” side of Santayana’s maxim, myself.

Before GeoCities was paved over, several teams of digital archivists saved as much as they could, and now there are GeoCities mirrors scattered around the Web. The best of them are Reocities,, Oocities, and of course, the Internet Archive. I’ve written a script that enables you to search all of them at once when you encounter a broken link to a Geocities site.

Just drag the “Dig GeoCities!” bookmarklet (click the link to go get it; that’s not the bookmarklet itself) to your browser’s bookmarks bar (giving it a shorter name if you prefer) and when you try to open a broken GeoCities link, click the bookmarklet while the GeoCities error page is in front. Three more tabs (or windows, if you swing that way) will open to potential mirrors of the page you’re looking for, and the last one will display an Internet Archive link if it can’t find anything.

I wrote this bookmarklet because the GeoCities archives have yet to merge their data; sometimes one or two will preserve a page, but not the others, and some are only partial. I was inspired by the Resurrect Pages Firefox add-on, but nothing did quite what I wanted, even the add-on.  I would like to see Resurrect Pages incorporate this functionality in future for GeoCities URLs.

By the way, this is something I started sketching on paper over a week ago, well before I heard of the Yahoo/Tumblr merger. I’m releasing it under the GNU GPL 3.0 license, so feel free to adapt it for Tumblr when you guys inevitably need something like it up there in 2023.

Finally, here are some of my favorite GeoCities URLs for practice. Open each in a new tab/window and click the bookmarklet (on your bookmarks bar) to see the archived versions.

EDIT: Although this is quite a simple script, apparently it doesn’t work fully on Chrome because of a known bug introduced by Google in the overzealous pursuit of popup window blocking. I’ll see what I can do.

A visit to the Living Computer Museum, Seattle’s vintage computer jungle gym

My friend John Braley and I visited Seattle’s Living Computer Museum in early May 2013. The word “living” may seem like hyperbole when applied to the antique computers it houses, but actually, all of them work, and most can be used by visitors. There are computers that play games, and there are others you can program, if you know how. For example, I was able to write a short program for the Altair 8800, arguably the world’s first home computer, and watch it run on a teletype. There are also Mac Pluses just sitting there with boxes of diskettes you can insert, swap and run until you get bored, if you do. I’m going to bring a few of my old Mac floppies next time.

There are just a couple of rules the museum asks you to obey:

  1. If it has a blue rope in front of it, don’t touch it.
  2. If it has big, important-looking switches, don’t flip them.

These rules were easy to follow and did not feel constrictive.

You enter the museum in the gift shop; this is also where you buy tickets. I noticed a few retrocomputing books on the shop shelves that were already on my wishlist, such as one about the Antikythera Mechanism; however, I will probably buy these as ebooks later. Sorry, LCM.


Care for some punch?

This card punch sits near the front door on the main floor (that is, the second floor; the third floor is where they store, restore and undoubtedly re-store their other computers). It’s like a typewriter that can’t type lower-case letters, and has all its punctuation in the wrong place. (Also, it makes punch cards.)


A Hollerith heart for my sweetie

Almost the first thing I did was pounce on the punch card maker and make my wife Marty a card with her name on it and an ASCII heart ❤ — technically a Hollerith code heart, I guess. I was very careful and punched Marty’s card correctly on the first try.


Don’t Underestimate Freedom, Sirius Cybernetics Redmond!

Moving widdershins through the exhibits, I was surprised by how even-handed the presentation was, given that the Living Computer Museum was established by Paul Allen, co-founder of Microsoft. I was actually shocked to see this display, portraying the Linux penguin and GNU gnu. There was another display devoted entirely to Microsoft near the end, but it contained an ignominious instance of Microsoft Bob, among other things.

Remember Clippy the talking paper clip? Now imagine an entire operating system interface that’s practically nothing but Clippy, with talking dogs, mice, and so on, all of them Genuine People Personalities™. That’s Bob.

I also found that there were elements of virtual reality in Bob, because to reach different controls in the user interface, you have to pretend-walk through the notional house where the dogs and mice live, making it seem a bit like Snow Crash on the cheap, with a dash of Disney. Suddenly a couple of things about my first contract at Microsoft, on the Virtual Worlds research project, came into focus.


Me and my Xerox friend, Alto!

I would have gone to the LCM merely to see and play with a functioning Xerox Alto. The Alto is the direct source for most of the computer interfaces of the last 30 years — mice, bitmapped displays, the desktop metaphor, the lot — imitated first by Apple, then by Microsoft half a decade later. Unfortunately, this one was locked into kiosk mode and would only let you play pinball on it. I can see some sense in that; someone who wanted to vandalize the Alto could probably run roughshod in the machine’s powerful Smalltalk programming environment, and it’s not clear it would be easy to put right again quickly. Still, I wonder if there’s some way for a trufan to make an after-hours appointment…


Brain the size of a planet (L) versus brain the size of a tobacco mosaic virus (R)

There’s one corridor of the museum where all the 8-bit ‘puters of our (well, my) youth are set up. You gotcher Apple IIs, your TRS-80 Model Is (I was disappointed there were no Model 100s), your Commodore 64s… John had owned one of the latter, and became engrossed in a Sargon II chess game with the 64’s little sib, the VIC-20. I’m not sure why a three-time Washington State chess champion would want to slug it out with a machine having only 4K of RAM, but we patzers are not privy to the whims of our betters. (Note: I initially had John listed as a two-time champion, but in fact he was state champion three times. One of those wins was a tie for first place, which counts as a full championship under Washington State chess rules. Sorry, John. But zoom in on the VIC-20 screen. John is running this 4K chess program at Level 1. WTF, amigo?)


10 PRINT CHR$(205.5+RND(1)); : GOTO 10

By this time, I was getting tired, so I slumped in front of a Commodore 128 (which has a ’64 mode), typed in 10 PRINT, etc. and watched the pretty patterns for a while. John snapped the photo on the “pix or it didn’t happen” principle. (Remember CRT video scan lines? I sure didn’t, until I was sorting through these photos.)

On our way out, we watched a silent video of museum staff wrestling a Cray supercomputer. The supercomputer wasn’t on display yet, so we asked a docent how often they changed the exhibits. “We never have,” she said. “We only opened in October, and we’ve hardly had any visitors, so there’s no point.”

She remarked that it was nice to have visitors who were so into vintage computers, but she gave us an odd look when John told her that I was so into them, I had bought the model of slide rule used on the Apollo moon missions. I had it with me but refrained from showing it to her — and my loved ones say I have no discretion.

John and I vowed we would return to the Living Computer Museum soon. What a great place — and because its displays are themselves programmable computers, each with its own strengths, capable of an indefinite number of programs, you can hardly exhaust it in one trip. So go ye, people of Seattle and West Coast environs, to the Living Computer Museum, and give its staff a reason to move some furniture around and dust off the family antiques.

Don’t let the museum staff despair! Even though the LCM is backed by a multibillionaire, if we don’t support it, it won’t be around long. I’ve been to other computer museums and exhibits, and they’re mostly static. The Living Computer Museum may be the only museum in the world where all the computers — and the history — are living.

And now, a couple of bonus retrocomputing photos.


Slide rules in a Prague shop window, 1979

This photo was taken by my friend Gerry, a stalwart member of our Finnegans Wake reading group (as is John). Why was a shop displaying slide rules in such profusion? Were they actually selling them, or was it conceptual art? Electronic calculators hit the West in the early 1970s; were parts of the Eastern Bloc still using slide rules as late as 1979? Perhaps I’ll drop a line to the slide rule mailing list.


Unicomp, home of the M

This is the facade of the Unicomp building in Lexington, Kentucky. Unicomp makes the marvelous Model M keyboard on which I’m typing this post, and which I’ve mentioned here before. My sister-in-law Melinda and her husband Keith live a couple of blocks from the Unicomp factory, and when they read about my Model M obsession, they offered to shoot the front of the plant for me. Notice the kitsch keyboard keys spelling out UNICOMP. They look different from the ones on their web page, so I’m guessing the former predate the latter, as web pages are easy to change, buildings not so much.

We have now reached the end of the tour. Tip. Thank you for making a simple blog post very happy. Share and Enjoy!

The Once and Future Slide Rule, Great and Terrible

Because the most productive thing I’ve done today is receive a slide rule in the mail and learn how to multiply by pi in a novel way, let’s start with that as the basis for a blog post with which to rectify my sloth.

The slide rule I got is a Pickett N600-ES (“eye-saver”, meaning bright yellow) circa 1970 that I won on eBay for about $50. This model is relatively small, made of aluminum and therefore lightweight and durable, displaying a large number of “scales” or number lines with which to calculate. Those are some of the reasons this model was taken to the moon on no less than five Apollo missions, including Apollo 11 (Neil Armstrong and Buzz Aldrin both carried this very model) and Apollo 13, where, I trust, it served them well. And yes, those are some of the reasons I, in turn, bought this compact beauty.


Figure 1. Ceci n’est pas Buzz Aldrin’s actual fucking slide rule, man!



Figure 2. What the box for Buzz Aldrin’s slide rule would have looked like if he had lost the first one and bought a replacement a few years later out of his own pocket.

My slide-rule bender goes back only a month or so, but once I get interested in something, it’s hard to deflect me. First, I posted my top five personal retrocomputing desiderata, and then was intrigued when my friend Zenoli did the same and one of his was a decent slide rule of some kind.

Next, there was a long, unrelated thread about slide rules on the TRS-80 Model 100 list, a list which occasionally veers into other retrocomputing topics. It amused me that people were talking about whipping out their big ten-inch to impress younger engineers (I paraphrase, but only slightly), completely unironically. (Alas, I can only whip out six inches. Before today, I couldn’t even do that.)

Finally, one evening during some documentation builds at work, I started googling about, looking for slide rule manufacturers, and was astonished to discover that there are in some important senses literally none at present. I mean, not even for homeschoolers? I’m not being sarcastic; using a slide rule will improve your numeracy in ways that using a calculator or calculator app never will. It’s a mentat skill.

This is all we have: A few years ago ThinkGeek did manufacture one as a novelty, but the quality was poor and the experiment was not repeated. There is also a Japanese company called Concise that still manufactures special-purpose circular slide rules. And that’s it.

But they can hardly replace the little plastic slipstick my uncle gave me and taught me how to use when I was 10 (he worked at Boeing and had probably just gotten a calculator). For nostalgia is what this quixotic retropursuit is all about, no? (Not quite; see below.) Then, too, my wife Marty’s late father had one, and she thinks it’s here in the garage somewhere… Well, wish us luck with that.

While googling, I learned about the talismanic lunar magic of the N600-ES, and what a solid little performer it is generally, so I sniped one on eBay that was firing in a couple days. And now it’s mine. For me, that’s part of the “great” part of “great and terrible”.

What’s the “terrible” part? We built the Hoover Dam, the Empire State Building, and to a large extent, the Apollo program and its precursors with slide rules. That’s pretty badass, don’t you agree?

“Once and Future,” the “future” part

I assume I don’t need to explain the “once” part…

If you don’t want to buy an N600-ES yourself — or any other kind of slide rule — there are all kinds of “modern-day fun” (as the Retrobits Podcast says) to be had without one. For example, you can play with an N600-ES “virtual slide rule” emulator online or on your Android. There are virtual slide rules for iOS. too. In fact, there are a huge number of slide rule emulators available online and off, not just of my model.

Another bit of modern-day slide rule fun is the UltraLog, a slide rule that was scrupulously designed a couple of years ago by Zvi Doron (who is now deceased) but which was never built. The UltraLog was meant to be the slide-rule fan’s slide rule, about a foot and a half long with 40 well-chosen and ergonomically-presented scales (mine has about 20, and that’s considered a lot; the model Einstein and von Braun used had only nine). There were incipient plans for an independently-funded production run of 500; this is the kind of thing destined for success on Kickstarter, but perhaps Zvi wasn’t familiar with that business model. It might even succeed today. In any case, there seem to be high-quality digital graphics of the UltraLog available; why can’t there be an online UltraLog emulator, at least? (I’ll get right on it.)

There is, by the way, a really good course for learning how to use slide rules at the online International Slide Rule Museum, but it won’t give you much theory. If you want to learn why a slide rule works as well as how, I highly recommend Isaac Asimov‘s lucid 1965 book An Easy Introduction to the Slide Rule, available as a PDF, also at the Museum, or as a used pbook for extortionate prices from your friendly online bookseller.

The gaming/retrocomputing connection

So why am I obsessed with slide rules, and retrocomputing generally?

I’m writing a dictionary of imaginary games notionally published on the equally imaginary planet Glob. A few days ago, I was musing about the games with slide rules there, where they can calculate with things other than numbers, such as days of the week, months of the year, and planets of the solar system. (Yes, I figured out how to do this; my book is “design fiction”, so every game in it is possible to implement in theory. I hope people do, in fact, after the book is published.)

It was then I understood the reason why all this time that I’ve been sketching imaginary games, I’ve also been busy sketching imaginary retrocomputers: machines that still boot into Lisp or Forth, “writer’s notebook” computers with the “cinematic form factor” similar to the Model 100 but with higher resolution, and so on. The people of Glob are my people, as the Elves are Tolkien’s, and they share my aesthetics, as the Elves share Tolkien’s. And I like elegant things.

I am no fan of the board games Advanced Squad Leader or Star Fleet Battles; I can barely comprehend (com-prehend, “togethergrasp”) in my mind the 30-page rulebook to Elder Sign, let alone its big sib Arkham Horror — or, I flatter myself, I don’t care to. The most fun I had at game night recently was playing Nonesuch, a simple trick-taking game for the Decktet that nevertheless offers plenty of emergent complexity. I enjoy the complex, rather than the complicated. I enjoy things I can “grasp together” in my mind and turn from side to side to see, yet which still surprise me — whether they be card games, computer games, or computers.

Returning to computers, I had to install one of the smaller versions of Microsoft Visual Studio at work the other day. Do you know how big the install was? Over seven gigabytes. Do you know how big all of the firmware native to my 1987 Tandy 102 laptop is, including all the applications, and the operating system, such as it is? 32 kilobytes. Does Visual Studio do more than my Tandy 102? Sure, a lot more. Does it do five orders of magnitude more? Does it have 221,000 times more functionality? I’ve been using the previous version for most of a year, and I assure you it does not. (Don’t accuse me of Microsoft-bashing; Microsoft also wrote the Model 100 / Tandy 102 firmware I appreciate back in 1982. Famously, it’s the last code Bill Gates ever touched.) I like elegant computers too, and often that means retrocomputers.

So for games, give me chess variants, games with slide rules, and ten-dimensional card game systems that are nevertheless less complicated than Dominion. For computers, give me the Model 100 and its kin, not Visual Studio.

This is largely the origin of my retrofascination.

Model Mmm

If you have noticed that this post is longer than usual, it may be because I have been writing it on an item from my retrocomputing wishlist: a Model M keyboard, specifically a brand-new Unicomp Ultra Classic USB keyboard. After years of using a netbook as my main computer, I had forgotten until my Tandy 102 how sweet it can be to write on a real computer keyboard, and they don’t come much realer or sweeter than the Model M.


So that’s one item (plus a slide rule bonus) off my wishlist, and four to go. I may give up on the Jupiter Ace, though, because the FIGnition kit, modeled in some ways on the Ace, is so much more available, and I stand to learn much by building one.

Finally, for more information about slide rules than you probably care to know — but it’s curated! — let me direct you to my slide rule bookmarks on Pinboard.

Image credits


10 PRINT on the Model T

Last year, MIT Press released a book that examines computing through a miniature art form: the BASIC-language one-liner, or one-line program, and the subculture surrounding it. The title of the book is 10 PRINT CHR$(205.5+RND(1)); : GOTO 10 (or 10 PRINT for short). You can buy a paper copy or download a free ebook from

The unusual title of the book is the one-liner itself, a famous one for the Commodore 64 computer that draws an hypnotic, flowing maze pattern on the screen. This maze is the starting point for all the authors’ speculations and essays, and they range widely.

For context, here is a video of the 10 PRINT pattern in action.

As an example of what is to be found in the book, there is a history of mazes and labyrinths; a survey of repeating mathematical shapes in modern art such as dance; and a couple of chapters devoted to porting the one-liner to other platforms. I found that the Applesoft BASIC version given (for the Apple II+ and later) works just the same on my Model T (TRS-80 Model 100 / Tandy 102), because both BASICs are typical Microsoft implementations of the era. However, because both the Apple and the T lack the special graphic characters that make up the maze on the C64, this version uses slash and backslash characters instead (/ and \), and the result is a little unsatisfying.

10 PRINT CHR$(47+(INT(RND(1)*2)*45)); : GOTO 10

Here is a screenshot of this Applesoft code running on the Model T (actually the Virtual T 1.5 emulator running on my Ubuntu netbook). Note that this pattern, and all the others, is moving and constantly growing. (Click to enlarge.)


I decided to see if I could improve on the canonical Applesoft version with some of the Model T’s own graphic characters, and used 4 of them instead of 2 (characters 251 through 254). My one-liner is shorter than the Applesoft version, and the result is more graphically striking, but it doesn’t generate a maze so much as an irregular network of caves. Not quite what I was going for, but if the Model T used screensavers, this would be a pretty good one, I think. Note that this Model T pattern and some of the others below can be duplicated fairly closely on the Commodore 64 as well (see the “Variations in Basic” chapter).

10 PRINT CHR$(251+(INT(RND(1)*4))); : GOTO 10


I wondered if any M100 mailing list members  who’d worked with the graphics characters on the Model T would like to try improving my version and posting their code back to the list, and several did. Jan VANDEN BOSSCHE was the first to respond, saying, “I don’t have a Model T handy – not even an emulator – but what about this?”

10 PRINT CHR$(229.5+RND(1)); : GOTO 10


A nice pattern, especially for writing it in his head. I also like how he managed to keep the “char.5” trick from the original. Jan said, “I could keep the .5 trick because these characters are also next to each other, just like the original C=64 ones.”

Willard Goosey’s judgment was, “Neat pattern, but too closed in to be a maze.” Next, Donald Kyllo offered the following one-liner, to which Willard responded, “Now that’s a maze generator!” I concur.

10 PRINTCHR$(240+INT(RND(1)*10));:GOTO10


Finally, Ken Pettit, a VIP in the Model T community (he runs the Club100 user group and invented the popular NADSBox storage device for the Model T), had more or less the last word. He wrote, ‘Okay, well this sorta breaks the spirit of “10 PRINT”, but I have a one-liner that produces very similar graphics to the C64’s one-liner.  I make the first statement a “10 PRINT” by printing a CHR$(12) (clear screen) in an attempt to keep with tradition of “10 PRINT”.  Otherwise this uses the line command.  Take it for what it is.’

10 PRINTCHR$(12):FORC%=0TO5000:V%=INT(RND(1)+.5):X%=(C%MOD30)*8:Y%=INT((C%/30)MOD8)*8:LINE(X%,Y%)-(X%+7,Y%+7),0,BF:LINE(X%,Y%+7*V%)-(X%+7,Y%+7*(1-V%)):NEXT


I think this and Don Kyllo’s are my favorites. Don’s is more elegant, more in keeping with the original code, but Ken reproduces the original Commodore graphics better. It doesn’t scroll like the others, but fills the screen and starts at the top again with an intriguing ripple effect.

I don’t think that Ken breaks the spirit of 10 PRINT entirely. At least it’s a one-liner, unlike most of the Processing ports in the book, which take a page. On the other hand, the Processing programmers were trying to reproduce the Commodore 64 experience as exactly as possible, as Ken was. At the other extreme, one of the 10 PRINT authors has a student who ported 10 PRINT to (if I recall correctly) 8 bytes of assembly language.

Juan Castro spoke up with a Mattel Aquarius port (!). He remarked, “[The Aquarius] has the convenient ‘spans all character cell’ slashes.” That’s not a port I expected to see.

To my remark that unlike the Aquarius, the Model T doesn’t seem to have graphics characters that fill their cells, John R. Hogerhuis responded, “Alphanumeric and punctuation characters generally don’t fill the cell because of the reserved ‘descender’ line. But the line drawing and block  graphics characters fill the cell.”

Apart from the usual retrotechnical knowhow on the list, there was an unusual amount of artistic and cultural back-and-forth, as well as a fair amount of negative reaction. Paper copies of 10 PRINT have been selling very well, but it has been a little controversial. Some people think it’s pointlessly academic. I read it from front to back and enjoyed it a great deal, and I will point out that some of the authors of the book are technically adept professional developers of games and other applications for platforms as diverse as Facebook and the Atari 2600, not atechnical pomo flyweights.

Books recommended on-list for people who enjoy 10 PRINT include:

And that is where we left the conversation, Reader, but it’s not over. Please leave a comment with your own perspective on the 10 PRINT phenomenon. Have a port to an obscure platform, a link to a video of one, a favorite one-liner with a different purpose, news about a similar project, or hate mail? As long as it’s not pink and doesn’t come in a can, please comment away.