Dan Q

The Elegance of the ASCII Table

Duration 15:19

Podcast Version

This post is also available as a podcast. Listen here, download for later, or subscribe wherever you consume podcasts.

If you’ve been a programmer or programming-adjacent nerd¹ for a while, you’ll have doubtless come across an ASCII table.

An ASCII table is useful. But did you know it’s also beautiful and elegant.

ASCII‘s still very-much around; even if you’re transmitting modern Unicode³ the most-popular encoding format UTF-8 is specifically-designed to be backwards-compatible with ASCII! If you decoded this page as ASCII you’d get the gist of it… so long as you ignored the garbage characters at the end of this sentence! 😁

History

ASCII was initially standardised in X3.4-1963 (which just rolls off the tongue, doesn’t it?) which assigned meanings to 100 of the potential 128 codepoints presented by a 7-bit⁴ binary representation: that is, binary values 0000000 through 1111111:

If you’ve already guessed where I’m going with this, you might be interested to look at the X3.4-1963 table and see that yes, many of the same elegant design choices I’ll be talking about later already existed back in 1963. That’s really cool!

Table

In case you’re not yet intimately familiar with it, let’s take a look at an ASCII table. I’ve colour-coded some of the bits I think are most-beautiful:

That table only shows decimal and hexadecimal values for each character, but we’re going to need some binary too, to really appreciate some of the things that make ASCII sublime and clever.

Control codes

The first 32 “characters” (and, arguably, the final one) aren’t things that you can see, but commands sent between machines to provide additional instructions. You might be familiar with carriage return (0D) and line feed (0A) which mean “go back to the beginning of this line” and “advance to the next line”, respectively⁵. Many of the others don’t see widespread use any more – they were designed for very different kinds of computer systems than we routinely use today – but they’re all still there.

32 is a power of two, which means that you’d rightly expect these control codes to mathematically share a particular “pattern” in their binary representation with one another, distinct from the rest of the table. And they do! All of the control codes follow the pattern 00_____: that is, they begin with two zeroes. So when you’re reading 7-bit ASCII⁶, if it starts with 00, it’s a non-printing character. Otherwise it’s a printing character.

Not only does this pattern make it easy for humans to read (and, with it, makes the code less-arbitrary and more-beautiful); it also helps if you’re an ancient slow computer system comparing one bit of information at a time. In this case, you can use a decision tree to make shortcuts.

Two rolls of punched paper tape. — That there’s one exception in the control codes: *DEL* is the *last* character in the table, represented by the binary number `1111111`. This is a historical throwback to paper tape, where the keyboard would punch some permutation of seven holes to represent the ones and zeros of each character. You can’t *delete* holes once they’ve been punched, so the only way to mark a character as invalid was to rewind the tape and punch out *all* the holes in that position: i.e. all `1`s.

Space

The first printing character is space; it’s an invisible character, but it’s still one that has meaning to humans, so it’s not a control character (this sounds obvious today, but it was actually the source of some semantic argument when the ASCII standard was first being discussed).

Putting it numerically before any other printing character was a very carefully-considered and deliberate choice. The reason: sorting. For a computer to sort a list (of files, strings, or whatever) it’s easiest if it can do so numerically, using the same character conversion table as it uses for all other purposes⁷. The space character must naturally come before other characters, or else John Smith won’t appear before Johnny Five in a computer-sorted list as you’d expect him to.

Being the first printing character, space also enjoys a beautiful and memorable binary representation that a human can easily recognise: 0100000.

Numbers

The position of the Arabic numbers 0-9 is no coincidence, either. Their position means that they start with zero at the nice round binary value 0110000 (and similarly round hex value 30) and continue sequentially, giving:

Binary	Hex	Decimal digit (character)
`011 0000`	`30`	0
`011 0001`	`31`	1
`011 0010`	`32`	2
`011 0011`	`33`	3
`011 0100`	`34`	4
`011 0101`	`35`	5
`011 0110`	`36`	6
`011 0111`	`37`	7
`011 1000`	`38`	8
`011 1001`	`39`	9

The last four digits of the binary are a representation of the value of the decimal digit depicted. And the last digit of the hexadecimal representation is the decimal digit. That’s just brilliant!

If you’re using this post as a way to teach yourself to “read” binary-formatted ASCII in your head, the rule to take away here is: if it begins 011, treat the remainder as a binary representation of an actual number. You’ll probably be right: if the number you get is above 9, it’s probably some kind of punctuation instead.

Shifted Numbers

Subtract 0010000 from each of the numbers and you get the shifted numbers. The first one’s occupied by the space character already, which is a shame, but for the rest of them, the characters are what you get if you press the shift key and that number key at the same time.

“No it’s not!” I hear you cry. Okay, you’re probably right. I’m using a 105-key ISO/UK QWERTY keyboard and… only four of the nine digits 1-9 have their shifted variants properly represented in ASCII.

That, I’m afraid, is because ASCII was based not on modern computer keyboards but on the shifted positions of a Remington No. 2 mechanical typewriter – whose shifted layout was the closest compromise we could find as a standard at the time, I imagine. But hey, you got to learn something about typewriters today, if that’s any consolation.

A Remington Portable No. 3 typewriter. — Bonus fun fact: early mechanical typewriters omitted a number 1: it was expected that you’d use the letter I. That’s fine for printed work, but not much help for computer-readable data.

Letters

Like the numbers, the letters get a pattern. After the @-symbol at 1000000, the uppercase letters all begin 10, followed by the binary representation of their position in the alphabet. 1 = A = 1000001, 2 = B = 1000010, and so on up to 26 = Z = 1011010. If you can learn the numbers of the positions of the letters in the alphabet, and you can count in binary, you now know enough to be able to read any ASCII uppercase letter that’s been encoded as binary⁸.

And once you know the uppercase letters, the lowercase ones are easy too. Their position in the table means that they’re all exactly 0100000 higher than the uppercase variants; i.e. all the lowercase letters begin 11! 1 = a = 1100001, 2 = b = 1100010, and 26 = z = 1111010.

If you’re wondering why the uppercase letters come first, the answer again is sorting: also the fact that the first implementation of ASCII, which we saw above, was put together before it was certain that computer systems would need separate character codes for upper and lowercase letters (you could conceive of an alternative implementation that instead sent control codes to instruct the recipient to switch case, for example). Given the ways in which the technology is now used, I’m glad they eventually made the decision they did.

Beauty

There’s a strange and subtle charm to ASCII. Given that we all use it (or things derived from it) literally all the time in our modern lives and our everyday devices, it’s easy to think of it as just some arbitrary encoding.

But the choices made in deciding what streams of ones and zeroes would represent which characters expose a refined logic. It’s aesthetically pleasing, and littered with historical artefacts that teach us a hidden history of computing. And it’s built atop patterns that are sufficiently sophisticated to facilitate powerful processing while being coherent enough for a human to memorise, learn, and understand.

Footnotes

¹ Programming-adjacent? Yeah. For example, geocachers who’ve ever had to decode a puzzle-geocache where the coordinates were presented in binary (by which I mean: a binary representation of ASCII) are “programming-adjacent nerds” for the purposes of this discussion.

² In both the book and the film, Mark Watney divides a circle around the recovered Pathfinder lander into segments corresponding to hexadecimal digits 0 through F to allow the rotation of its camera (by operators on Earth) to transmit pairs of 4-bit words. Two 4-bit words makes an 8-bit byte that he can decode as ASCII, thereby effecting a means to re-establish communication with Earth.

³ Y’know, so that you can type all those emoji you love so much.

⁴ ASCII is often thought of as an 8-bit code, but it’s not: it’s 7-bit. That’s why virtually every ASCII message you see starts every octet with a zero. 8-bits is a convenient number for transmission purposes (thanks mostly to being a power of two), but early 8-bit systems would be far more-likely to use the 8th bit as a parity check, to help detect transmission errors. Of course, there’s also nothing to say you can’t just transmit a stream of 7-bit characters back to back!

⁵ Back when data was sent to teletype printers these two characters had a distinct different meaning, and sometimes they were so slow at returning their heads to the left-hand-side of the paper that you’d also need to send a few null bytes e.g. 0D 0A 00 00 00 00 to make sure that the print head had gotten settled into the right place before you sent more data: printers didn’t have memory buffers at this point! For compatibility with teletypes, early minicomputers followed the same carriage return plus line feed convention, even when outputting text to screens. Then to maintain backwards compatibility with those systems, the next generation of computers would also use both a carriage return and a line feed character to mean “next line”. And so, in the modern day, many computer systems (including Windows most of the time, and many Internet protocols) still continue to use the combination of a carriage return and a line feed character every time they want to say “next line”; a redundancy build for a chain of backwards-compatibility that ceased to be relevant decades ago but which remains with us forever as part of our digital heritage.

⁶ Got 8 binary digits in front of you? The first digit is probably zero. Drop it. Now you’ve got 7-bit ASCII. Sorted.

⁷ I’m hugely grateful to section 13.8 of Coded Character Sets, History and Development by Charles E. Mackenzie (1980), the entire text of which is available freely online, for helping me to understand the importance of the position of the space character within the ASCII character set. While most of what I’ve written in this blog post were things I already knew, I’d never fully grasped its significance of the space character’s location until today!

⁸ I’m sure you know this already, but in case you’re one of today’s lucky 10,000 to discover that the reason we call the majuscule and minuscule letters “uppercase” and “lowercase”, respectively, dates to 19th century printing, when moveable type would be stored in a box (a “type case”) corresponding to its character type. The “upper” case was where the capital letters would typically be stored.

Good Food, Bad Authorisation

I was browsing (BBC) Good Food today when I noticed something I’d not seen before: a “premium” recipe, available on their “app only”:

I clicked on the “premium” recipe and… it looked just like any other recipe. I guess it’s not actually restricted after all?

Just out of curiosity, I fired up a more-vanilla web browser and tried to visit the same page. Now I saw an overlay and modal attempting¹ to restrict access to the content:

It turns out their entire effort to restrict access to their premium content… is implemented in client-side JavaScript. Even when I did see the overlay and not get access to the recipe, all I needed to do was open my browser’s debugger and run document.body.classList.remove('tp-modal-open'); for(el of document.querySelectorAll('.tp-modal, .tp-backdrop')) el.remove(); and all the restrictions were lifted.

What a complete joke.

Why didn’t I even have to write my JavaScript two-liner to get past the restriction in my primary browser? Because I’m running privacy-protector Ghostery, and one of the services Ghostery blocks by-default is one called Piano. Good Food uses Piano to segment their audience in your browser, but they haven’t backed that by any, y’know, actual security so all of their content, “premium” or not, is available to anybody.

I’m guessing that Immediate Media (who bought the BBC Good Food brand a while back and have only just gotten around to stripping “BBC” out of the name) have decided that an ad-supported model isn’t working and have decided to monetise the site a little differently². Unfortunately, their attempt to differentiate premium from regular content was sufficiently half-hearted that I barely noticed that, too, gliding through the paywall without even noticing were it not for the fact that I wondered why there was a “premium” badge on some of their recipes.

Recipes probably aren’t considered a high-value target, of course. But I can tell you from experience that sometimes companies make basically this same mistake with much more-sensitive systems. The other year, for example, I discovered (and ethically disclosed) a fault in the implementation of the login forms of a major UK mobile network that meant that two-factor authentication could be bypassed entirely from the client-side.

These kinds of security mistakes are increasingly common on the Web as we train developers to think about the front-end first (and sometimes, exclusively). We need to do better.

Footnotes

¹ The fact that I could literally see the original content behind the modal was a bit of a giveaway that they’d only hidden it, not actually protected it in any way.

² I can see why they’d think that: personally, I didn’t even know there were ads on the site until I did the experiment above: turns out I was already blocking them, too, along with any anti-ad-blocking scripts that might have been running alongside.

Derpy McBlepsleep

Derpy McBlepsleep, diligently guarding the front door just in case somebody comes by with treats.

Write Websites

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Enbies and gentlefolk of the class of ‘24:

Write websites.

If I could offer you only one tip for the future, coding would be it. The long term benefits of coding websites remains unproved by scientists, however the rest of my advice has a basis in the joy of the indie web community’s experiences. I will dispense this advice now:

Enjoy the power and beauty of PHP; or never mind. You will not understand the power and beauty of PHP until your stack is completely jammed. But trust me, in 20 years you’ll look back at your old sites and recall in a way you can’t grasp now, how much possibility lay before you and how simple and fast they were. JS is not as blazingly fast as you imagine.

Don’t worry about the scaling; or worry, but know that premature scalability is as useful as chewing bubble gum if your project starts cosy and small. The real troubles on the web are apt to be things that never crossed your worried mind; if your project grows, scale it up on some idle Tuesday.

Code one thing every day that amuses you.

…

Sara Joy

Well that’s made my day.

I can’t say I loved Baz Luhrmann’s Everybody’s Free To Wear Sunscreen. I’m not sure it’s possible for anybody who lived through it being played to death in the late 1990s; a period of history when a popular song was basically inescapable. Also, it got parodied a lot. I must’ve seen a couple of dozen different parodies of varying quality in the early 2000s.

But it’s been long enough that I was, I guess, ready for one. And I couldn’t conceive of a better topic.

Y’see: the very message of the value of personal websites is, like Sunscreen, a nostalgic one. When I try to sell people on the benefits of a personal digital garden or blog, I tend to begin by pointing out that the best time to set up your own website is… like 20+ years ago.

But… the second-best time to start a personal website is right now. With cheap and free static hosting all over the place (and more-dynamic options not much-more expensive) and domain names still as variably-priced as they ever were, the biggest impediment is the learning curve… which is also the fun part! Siloed social media is either eating its own tail or else fighting to adapt to once again be part of a more-open Web, and there’s nothing that says “I’m part of the open Web” like owning your own online identity, carving out your own space, and expressing yourself there however you damn well like.

As always, this is a drum I’ll probably beat until I die, so feel free to get in touch if you want some help getting set up on the Web.

United Kingdom (the)

Remind me, do I live in “United Kingdom” or “United Kingdom (the)”? 😂

SkiFreeeeeeee

Rob Vincent said:

COME PLAY SOLITAIRE WITH US.

Rob Vincent

I always preferred SkiFree!

Vmail via FreshRSS

It’s time for… Dan Shares Yet Another FreshRSS XPath Scraping Recipe!

Vmail

I’m a huge fan of the XPath scraping feature of FreshRSS, my favourite feed reader (and one of the most important applications in my digital ecosystem). I’ve previously demonstrated how to use the feature to subscribe to Forward, reruns of The Far Side, and new The Far Side content, despite none of those sites having “official” feeds.

Vmail is cool. It’s vole.wtf’s (of ARCC etc. fame) community newsletter, and it’s as batshit crazy as you’d expect if you were to get the kinds of people who enjoy that site and asked them all to chip in on a newsletter.

Totes bonkers.

But email’s not how I like to consume this kind of media. So obviously, I scraped it.

Recipe

Want to subscribe to Vmail using your own copy of FreshRSS? Here’s the settings you’re looking for –

Type of feed source: HTML + XPath (Web scraping)
XPath for finding news items: //table/tbody/tr
It’s just a table with each row being a newsletter; simple!
XPath for item title: descendant::a
XPath for item content: .
XPath for item link (URL): descendant::a/@href
XPath for item date: descendant::td[1]
Custom date/time format: d M *y
The dates are in a format that’s like 01 May ’24 – two-digit days with leading zeros, three-letter months, and a two-digit year preceded by a curly quote, separated by spaces. That curl quote screws up PHP’s date parser, so we have to give it a hint.
XPath for unique item ID: descendant::th
Optional, but each issue’s got its own unique ID already anyway; we might as well use it!
Article CSS selector on original website: #vmail
Optional, but recommended: this option lets you read the entire content of each newsletter without leaving FreshRSS.

So yeah, FreshRSS continues to be amazing. And lately it’s helped me keep on top of the amazing/crazy of vole.wtf too.

The Eyebrow Painter

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

…

There are a whole bunch of things that could be the source for the name, e.g. where we found most of their work (The Dipylon Master) or the potter with whom they worked (the Amasis Painter), a favourite theme (The Athena Painter), the Museum that ended up with the most famous thing they did (The Berlin Painter) or a notable aspect of their style. Like, say, The Eyebrow Painter.

Guess what kind of pottery the Eyebrow Painter made?

…

AristotelianComplacency

Just excellent.

A frowning fish, painted onto a plate, surely makes for the best funerary offering.

Dan Q wrote note for GC9EXXX Church Micro 14129…Sutton

This checkin to GC9EXXX Church Micro 14129...Sutton reflects a geocaching.com log entry. See more of Dan's cache logs.

With thanks to Lydford Locators for their recent log, the hint has been improved.

A Pressure Cooker for Tea

Duration 5:15

Podcast Version

This post is also available as a podcast. Listen here, download for later, or subscribe wherever you consume podcasts.

I’m not a tea-drinker¹. But while making a cuppa for Ruth this morning, a thought occurred to me and I can’t for a moment believe that I’m the first person to think of it:

What about a pressure-cooker, but for tea?²

Hear me out.

It’s been stressed how important it is that the water used to brew the tea is 100℃, or close to it possible. That’s the boiling point of water at sea level, so you can’t really boil your kettle hotter than that or else the water runs away to pursue a new life as a cloud.

That temperature is needed to extract the flavours, apparently³. And that’s why you can’t get a good cup of tea at high altitudes, I’m told: by the time you’re 3000 metres above sea level, water boils at around 90℃ and most British people wilt at their inability to make a decent cuppa⁴.

It’s a question of pressure, right? Increase the pressure, and you increase the boiling point, allowing water to reach a higher temperature before it stops being a liquid and starts being a gas. Sooo… let’s invent something!

I’m thinking a container about the size of a medium-sized Thermos flask or a large keep-cup – you need thick walls to hold pressure, obviously – with a safety valve and a heating element, like a tiny version of a modern pressure cooker. The top half acts as the lid, and contains a compartment into which you put your teabag or loose leaves (optionally in an infuser). After being configured from the front panel, the water gets heated to a specified temperature – which can be above the ambient boiling point of water owing to the pressurisation – at which point the tea is released from the upper half. The temperature is maintained for a specified amount of time and then the user is notified so they can release the pressure, open the top, lift out the inner cup, remove the teabag, and enjoy their beverage.

This isn’t just about filling the niche market of “dissatisfied high-altitude tea drinkers”. Such a device would also be suitable for other folks who want a controlled tea experience. You could have it run on a timer and make you tea at a particular time, like a teasmade. You can set the temperature lower for a controlled brew of e.g. green tea at 70℃. But there’s one other question that a device like this might have the capacity to answer:

What is the ideal temperature for making black tea?

We’re told that it’s 100℃, but that’s probably an assumption based on the fact that that’s as hot as your kettle can get water to go, on account of physics. But if tea is bad when it’s brewed at 90℃ and good when it’s brewed at 100℃… maybe it’s even better when it’s brewed at 110℃!

A modern pressure cooker can easily maintain a liquid water temperature of 120℃, enabling excellent extraction of flavour into water (this is why a pressure cooker makes such excellent stock).

A mug of tea held by the handle. — It’s possible that the perfect cup of tea *hasn’t been invented yet*, owing to limitations in the boiling point of water.

I’m not the person to answer this question, because, as I said: I’m not a tea drinker. But surely somebody’s tried this⁵? It shouldn’t be too hard to retrofit a pressure cooker lid with a sealed compartment that releases, even if it’s just on a timer, to deposit some tea into some superheated water?

Because maybe, just maybe, superheated water makes better tea. And if so, there’s a possible market for my proposed device.

Footnotes

¹ I probably ought to be careful confessing to that or they’ll strip my British citizenship.

² Don’t worry, I know better than to suggest air-frying a cup of ta. What kind of nutter would do that?

³ Again, please not that I’m not a tea-drinker so I’m not really qualified to comment on the flavour of tea at all, let alone tea that’s been brewed at too-low a temperature.

⁴ Some high-altitude tea drinkers swear by switching from black tea to green tea, white tea, or oolong, which apparently release their aromatics at lower temperatures. But it feels like science, not compromise, ought to be the solution to this problem.

⁵ I can’t find the person who’s already tried this, if they exist, but maybe they’re out there somewhere?

Building a Secret Cabinet

We’ve recently had the attics of our house converted, and I moved my bedroom up to one of the newly-constructed rooms.

To make the space my own, I did a little light carpentry up there: starting with a necessary reshaping of the doors, then moving on to shelving and eventually… a secret cabinet!

I’d love to tell you about how I built it: but first, a disclaimer! I am a software engineer, and with good reason. Letting me near a soldering iron is ill-advised. Letting me use a table saw is tempting fate.

Letting me teach you anything about how you should use a soldering iron or a table saw is, frankly, asking for trouble.

A spirit level on an unfinished shelf, under a window and beneath an uncarpeted floor. — Knowing that I’d been short on shelf space in my old bedroom, I started work on fitting shelves for my new bedroom before the carpet had even arrived.

Building a secret cabinet wasn’t part of my plan, but came about naturally after I got started. I’d bought a stack of pine planks and – making use of Ruth’s table saw – cut them to squarely fit beneath each of the two dormer windows¹. While sanding and oiling the wood I realised that I had quite a selection of similarly-sized offcuts and found myself wondering if I could find a use for them.

Dan drinks a 0% alcohol beer in front of three upright planks of wood. — The hardest part of sanding and oiling wood on the hottest day of the year is all the beer breaks you have to take. Such a drag.

I figured I had enough lumber to insert a small cabinet into one of the bookshelves, and that got me thinking… what about if it were a secret cabinet, disguised as books unless you knew where to look. Or to go one step further: what if it had some kind of electronic locking mechanism that could be triggered from somewhere else in the room².

Magpie decal 'perched' on a light switch. — There are other ways in which I’ve made my new room distinctly-“mine” – like the pair of magpies – but probably the secret cabinet is the most-distinctive.

Not wanting to destroy a stack of real books, which is the traditional way to get a collection of book spines for the purpose of decorating a “fake bookshelf” panel³, I looked online and discovered the company that made the fake book spines used at the shop of my former employer. They looked ideal: carefully shaped and painted panels with either an old-school or contemporary look.

Buuut, they don’t seem to be well-equipped for short runs and are doubtless pricey, so I looked elsewhere and found the eBay presence of Beatty Lockey Antiques in Loewstof. They’d acquired a stack of them second-hand from the set of Netflix’s The School for Good and Evil.⁴

(By the way: at time of writing they’ve still got a few panels left, if you want to make your own…)

I absolutely must sing the praises of Brad at Beatty Lockey Antiques who, after the first delivery of fake book fronts was partially-damaged in transit, was super quick about helping me find the closest-available equivalent (I’d already measured-up based on the one I’d thought I was getting) and sent a replacement.

The cabinet is just a few bits of wood glued together and reinforced with L-shaped corner braces, with a trio of thin strips – made from leftover architrave board – attached using small brass hinges. The fake book fronts are stuck to the strips using double-sided mounting tape left over from installing a bathroom mirror. A simple magnetic clasp holds the door shut when pushed closed⁵, and the hinges are inclined to “want” the door to stand half-open, which means it only needs a gentle push away from the magnetic catch to swing it open.

I mounted a Raspberry Pi Zero W into a rear corner inside the cabinet⁶, and wired it up via a relay to what was sold to me as a “large push-pull solenoid”, then began experimenting with the position in which I’d need to mount it to allow it to “kick” open the door, against the force of the magnetic clasp⁷.

This was, amazingly, the hardest part of the whole project! Putting the solenoid too close to the door didn’t work: it couldn’t “push” it from a standing start. Too far away, and the natural give of the door took the strain without pushing it open. Just the right distance, and the latch had picked up enough momentum that its weight “kicked” the door away from the magnet and followed-through to ensure that it kept moving.

A second solenoid, mounted inside the top of the cabinet, slides into the “loop” part of a large bolt fitting, allowing the cabinet to be electronically “locked”.

A Raspberry Pi Zero, relay, and solenoid assembly on the bottom outside edge of the inside of the cabinet. — I seriously must’ve spent about an hour getting the position of that little “kicker” in the bottom right *just right*.

Next up came the software. I started with a very simple Python program⁸ that would run a webserver and, on particular requests, open the lock solenoid and push with the “kicker” solenoid.

#!/usr/bin/python
#
# a basic sample implementation of a web interface for a secret cabinet
#
# setup:
#   sudo apt install -y python3-flask
#   wget https://github.com/sbcshop/Zero-Relay/blob/master/pizero_2relay.py
#
# running:
#   sudo flask --app web run --host=0.0.0.0 --port 80

from flask import Flask, redirect, url_for
import pizero_2relay as pizero
from time import sleep

# set up pizero_2relay with the two relays attached to this Pi Zero:
r1 = pizero.relay("R1") # The "kicker" relay
r2 = pizero.relay("R2") # The "locking bolt" relay

app = Flask(__name__)

# GET / - nothing here
@app.route("/")
def index():
  return "Nothing to see here."

# GET /relay - show a page with "open" and "lock" links
@app.route("/relay")
def relay():
  return "<html><head><meta name='viewport' content='width=device-width, initial-scale=1'></head><body><ul><li><a href='/relay/open'>Open</a></li><li><a href='/relay/lock'>Lock</a></li></ul>"

# GET /relay/open - open the secret cabinet then return to /relay
# This ought to be a POST request in your implementation, and you probably
# want to add some security e.g. a 
@app.route("/relay/open")
def open():
  # Retract the lock:
  r2.off()
  sleep(0.5)
  # Fire the kicker twice:
  r1.on()
  sleep(0.25)
  r1.off()
  sleep(0.25)
  r1.on()
  sleep(0.25)
  r1.off()
  # Redirect back:
  return redirect(url_for('relay'))

@app.route("/relay/lock")
def lock():
  # Engage the lock:
  r2.on()
  return redirect(url_for('relay'))

Don’t use this code as-is on any kind of open network, obviously. Follow the comments for some tips on what you’ll need to change.

Once I had something I could trigger from a web browser or with curl, I could start experimenting with trigger mechanisms. I had a few ideas (and prototyped a couple of them), including:

A mercury tilt switch behind a different book, so you pull it to release the cabinet in the style of a classic movie secret door.
A microphone that listens for a specific pattern of knocks on a nearby surface.

I had far too much fun playing about with crappy prototypes.

An RFID reader mounted underneath another surface, and a tag on the underside of an ornament: moving the ornament to the “right” place on the surface triggers the cabinet (elsewhere in the room).
The current design, shown in the video above, where a code⁹ is transmitted to the cabinet for verification.

I think I’m happy with what I’ve got going on with it now. And it’s been a good opportunity to improve my carpentry, electronics, and Python.

Footnotes

¹ The two dormer windows, wouldn’t you guarantee it, were significantly different widths despite each housing a window of the same width. Such are the quirks of extending a building that the previous occupier had previously half-heartedly tried to extend, I guess.

² Why yes, I am a big fan of escape rooms. Why do you ask?

³ For one thing, I live with JTA, and I’m confident that he’d somehow be able to hear the silent screams of whatever trashy novels I opted to sacrifice for the good of the project.

⁴ As a bonus, my 10-year-old is a big fan of the book series that inspired the film (and a more-muted fan of the film itself) and she was ever-so excited at my project using real-life parts of the set of the movie… that she’s asked me to make a similar secret cabinet for her, when we get around to redecorating her room later in the year!

⁵ If I did it again, I might consider using a low-powered electromagnetic lock to hold the door shut. In this design, I used a permanent magnet and a pair of latch solenoids: one to operate a bolt, the second to “kick” the door open against the pull of the magnet, and… it feels a little clumsier than a magnetic lock might’ve.

⁶ That double-sided mounting tape really came in handy for this project!

⁷ Props to vlogger Technology Connections, one of whose excellent videos on the functionality of 1970s pinball tables – maybe this one? – taught me what a latch solenoid was in the first place, last year, which probably saved me from the embarrassment of trying to do this kind of thing with, I don’t know, a stepper motor or something.

⁸ I’m not a big fan of Python normally, but the people who made my relays had some up with a convenience library for them that was written in it, so I figured it would do.

⁹ Obviously the code isn’t A-B; I changed it temporarily for the video.

Ladybird Browser

I’ve been playing with the (pre-Alpha version of) Ladybird, and it fills me with such joy and excitement.

Browser diversity

Back in 2018, while other Web developers were celebrating, I expressed my dismay at the news that Microsoft Edge was on the cusp of switching from using Microsoft’s own browser engine EdgeHTML to using Blink. Blink is the engine that powers almost all other mainstream browsers; all but Firefox, which continues to stand atop Gecko.

The developers who celebrated this loss of rendering engine diversity were, I suppose, happy to have one fewer browser in which they must necessarily test their work. I guess these are the same developers who don’t test the sites they develop for accessibility (does your site work if you can’t see the images? what about with a keyboard but without a pointing device? how about if you’re colourblind?), or consider what might happen if a part of their site fails (what if the third-party CDN that hosts your JavaScript libraries goes down or is blocked by the user’s security software or their ISP?).

But I was sad, because – as I observed after Andre Alves Garzia succinctly spelled it out – browser engines are an endangered species. Building a new browser that supports the myriad complexities of the modern Web is such a huge endeavour that it’s unlikely to occur from scratch: from this point on, all “new” browsers are likely to be based upon an existing browser engine.

Engine diversity is important. Last time we had a lull in engine diversity, the Web got stuck, stagnating in the shadow of Internet Explorer 6’s dominance and under the thumb of Microsoft’s interests. I don’t want those days to come back; that’s a big part of why Firefox is my primary web browser.

A Ladybird book browser

Spoof cover for "The Ladybird Book of The Browser" — I actually still own a copy of the book from which I adapted this cover!

Ladybird is a genuine new browser engine. Y’know, that thing I said that we might never see happen again! So how’ve they made it happen?

It helps that it’s not quite starting from scratch. It’s starting point is the HTML viewer component from SerenityOS. And… it’s pretty good. It’s DOM processing’s solid, it seems to support enough JavaScript and CSS that the modern Web is usable, even if it’s not beautiful 100% of the time.

They’re not even expecting to make an Alpha release until next year! Right now if you want to use it at all, you’re going to need to compile the code for yourself and fight with a plethora of bugs, but it works and that, all by itself, is really exciting.

They’ve got four full-time engineers, funded off donations, with three more expected to join, plus a stack of volunteer contributors on Github. I’ve raised my first issue against the repo; sadly my C++ probably isn’t strong enough to be able to help more-directly, even if I somehow did have enough free time, which I don’t. But I’ll be watching-from-afar this wonderful, ambitious, and ideologically-sound initiative.

#100DaysToOffload

Woop! This is my 100th post of the year (stats), even using my more-conservative/pedant-friendly “don’t count checkins/reposts/etc. rule. If you’re not a pedant, I achieved #100DaysToOffload when I found a geocache alongside Regents Canal while changing trains to go to Amsterdam where I played games with my new work team, looked at windows and learned about how they’ve been taxed, and got nerdsniped by a bus depot. In any case: whether you’re a pedant or not you’ve got to agree I’ve achieved it now!

Ranking Every Elevator in the Myst Series

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Dustin Garner

Part of the joy of the collaborative Internet is that people can share their passion. Today’s example comes from this YouTuber who’s made an hour long video demonstrating and ranking the 35 elevators in the first five games in the Myst series.

Starting with a discussion of what defines an elevator, the video goes on to show off some of the worst of the lifts in the series of games (mostly those that are uninspired, pointless, or which have confusing interfaces) before moving on to the well-liked majority.

I only ever played the first two Myst games (and certainly haven’t played the first since, what, the mid-1990s?) and I don’t think I finished either. But that didn’t stop me watching the entirety of this video and revelling in the sheer level of dedication and focus it’ll have taken on the part of the creator. When I made my (mere 15-minute!) video describing my favourite video game Easter Egg I spent tens of hours over the prior weeks researching the quirk and its background, configuring a copy of the (elderly) game so that it’d play and record in the way I wanted, and of course playing through the game far enough to be able to fully demonstrate the Easter Egg. Dustin’s video, which doubtless involved replaying (possibly multiple times) five different games released over a 12-year window is mindblowing by comparison.

I don’t really care about the Myst series. I care even less about its elevators. But I really enjoyed this video, if only for its creator’s enthusiasm.

Information Trajectory

Humans invented Wikipedia, which made accessing information highly-convenient, at the risk of questions about its authenticity¹.

Then humans invented GPTs, which made accessing information even more-convenient² at the expense of introducing hallucinations that can be even harder to verify and check.

Is humanity’s long-term plan to invent something that spews complete nonsense that’s simultaneously impossible to conclusively deny?³

Footnotes

¹ I’m well aware that in many subject areas Wikipedia routinely outranks many other sources for accuracy. But the point remains, because you’ve no idea what the bias of randomuser123 is; even if you check the sources they cite, you don’t know what sources they omitted to include. I love Wikipedia, but I can’t deny its weaknesses.

² Sure, ChatGPT and friends aren’t always more-convenient. But if you need to summarise information from several sources, you might find them a more-suitable tool than those which came before. Why do I feel the need to add so many footnotes to what should have been a throwaway comment?

³ Actually, now I think about it, I’m confident that I can name some politicians who are ahead of the machines, for now.

Science Weekend

This weekend was full of science.

Research

String of large electromagnets used for steering an electron beam. — If you wanna bend a stream of electrons travelling at nearly the speed of light, you’re gonna need a lot of big magnets.

This started on Saturday with a trip to the Harwell Campus, whose first open day in eight years provided a rare opportunity for us to get up close with cutting edge science (plus some very kid-friendly and accessible displays) as well as visit the synchrotron at Diamond Light Source.

Dan with a child in front of beamlines coming out of the Diamond Light Synchrotron ring. — It’s hard to convey the scale of the thing; turns out you need a big ol’ ring if you want to spin electrons fast enough to generate a meaningful amount of magnetobremsstrahlung radiation.

The whole thing’s highly-recommended if you’re able to get to one of their open days in the future, give it a look. I was particularly pleased to see how enthused about science it made the kids, and what clever questions they asked.

For example: the 7-year-old spent a long time cracking a variety of ciphers in the computing tent (and even spotted a flaw in one of the challenge questions that the exhibitors then had to hand-correct on all their handouts!); the 10-year-old enjoyed quizzing a researcher who’d been using x-ray crystallography of proteins.

Medicine

And then on Sunday I finally got a long-overdue visit to my nearest spirometry specialist for a suite of experiments to try to work out what exactly is wrong with my lungs, which continue to be a minor medical mystery.

Dan holds a piece of medical apparatus to his mouth. — “Once you’ve got your breath back, let’s fill you with drugs and do those experiments again…”

It was… surprisingly knackering. Though perhaps that’s mostly because once I was full of drugs I felt briefly superpowered and went running around the grounds of the wonderfully-named Brill Hill Windmill with the dog until was panting in pretty much the way that I might normally have been, absent an unusually-high dose of medication.

For amusement purposes alone, I’d be more-likely to recommend the first day’s science activities than the second, but I can’t deny that it’s cool to collect a load of data about your own body and how it works in a monitorable, replicable way. And maybe, just maybe, start to get to the bottom of why my breathing’s getting so much worse these last few years!