John Graham-Cumming

Controlling the Taylor Swift Eras Tour wristbands with Flipper Zero

Many large concerts feature wristbands that light up on command. They are used to produce varied visual effects across a stadium. One compan...

Kelly Rowland couldn't have used the =HYPERLINK() function to message Nelly

The Kelly Rowland/Nelly song Dilemma features an infamous scene amongst nerds where Kelly Rowland tries to send a message to Nelly using a ...

There's a ridiculous amount of tech in a disposable vape

So, I'm walking through a park when I see this thing lying on the ground: It's a disposable vape that someone has discarded because it's emp...

The secret message hidden in every HTTP/2 connection

If you spy on an HTTP/2 connection starting up you'll notice that it sends an almost-but-not-quite valid HTTP request at the very start of...

My Email Canary

Despite the fact that I use really long passwords and two-factor authentication wherever it's available I still worry that someone might b...

Retrieving 1TB of data from a faulty drive with the help of woodworking tools

So, a while ago I built a gaming PC with the following specification: Case Dan A4 v4.1 Motherboard Z690I Strix Gaming Pro...

Original WWW proposal is a Word for Macintosh 4 file from 1990, can we open it?

The W3C has a page with the original WWW proposal from Tim Berners-Lee. One of the downloads says The original document file (I think - I ...

How I coded in 1985

Back in 1985 I worked on the computerization of a machine designed to stick labels on bottles. The company that made the machines was using...

The greatest Google Mail feature you may not be using

There's a wonderfully powerful and subtle technique in Google Mail that can be used to enhance every reply you make to a mail: if you selec...

"Hacker News" for retro computing and gaming

I noticed over time that I was drawn to the retro computing or gaming posts on Hacker News . So, I've set up a dedicated web site in the sam...

Guest WiFi using a QR code

On my home network I have guest WiFi configured and when guests come round they need to know the password. Happily there's a way to make thi...

Low-background Steel: content without AI contamination

Somehow I forgot to blog my site: https://lowbackgroundsteel.ai/ . I created it back in March 2023 as a clearinghouse for online resources t...

One line you should add to every makefile

If you're using GNU make and you need help debugging a makefile then there's a single line your should add. And it's so useful that you sho...

Cracking an old ZIP file to help open source the ANC's "Vula" secret crypto code

It's not often that you find yourself staring at code that few people have ever seen, code that was an important part in bringing down the a...

A non-mathematical explanation of one way functions

Alice and Bob are crossword enthusiasts. Every morning they rush to complete the Daily Telegraph cryptic crossword . One morning Alice fini...

Why don't they just..?

It seems every time I come across a story about the Mars Curiosity rover there will be many people commenting on the technology used start...

Pimping my Casio with Oddly Specific Objects' alternate motherboard and firmware

Some time ago I bought a replacement motherboard for my classic Casio F-91W from Crowd Supply. The project keeps the original Casio LCD but...

Ambient bus arrival monitor from hacked Linksys WRT54GL

London's Transport for London has a wonderful service called Countdown that can give live bus arrival times. For example, here's a page s...

Steve Ballmer's incorrect binary search interview question

In this short video Steve Ballmer talks about a puzzle question he would ask candidates interviewing at Microsoft. Solving it is based on b...

If you care about security you might want to move the iPhone Camera app

There's a quirk in the iPhone Camera app that can drive a security conscious iPhone owner crazy: if you touch your finger on the Camera app ...

Is a movie prop the ultimate laptop bag?

A while back I attended a Cloudflare board meeting and carried my laptop in a brown paper bag from a grocery store. This elicited a few com...

Some things I've learnt about programming

I've been programming for over 30 years from machines that seem puny today (Z80 and 6502 based) to the latest kit using languages that rang...

Making an old USB printer support Apple AirPrint using a Raspberry Pi

There are longer tutorials on how to connect a USB printer to a Raspberry Pi and make it accessible via AirPrint but here's the minimal one ...

A tale of two cultures

Getting around the London 2012 branding police

The Guardian reported the other day on the London 2012 Olympics branding police who ensure that words like London, 2012 or Games aren't be...

“The GNU Make Book”: probably more than you ever wanted to know about make

So, it's finally here. My second book, entitled The GNU Make Book and published by No Starch Press later this month (electronically it's a...

Apple's amusingly round reuse figures

If you take a look at Apple's Environment page you might well be impressed by the amount of reuse Apple is getting by taking back devices....

Pimping My Casio: Part Deux

Close to three years ago I wrote about using Oddly Specific Objects' alternate "motherboard" to modify a classic Casio F-91W watch: Pimping...

UseTheSource: a job board for hackers

Call yourself a 'brogrammer'? Then get the hell away from me.