Compsci

The problem: Most computer users manually save versions of files with names like Presentation-2027-Jan-11, followed later by Presentation-2027-Jan-11-UPDATED and Presentation-2027-For-Sally-Only, perhaps with Presentation-panic-edits-before-event. This is manual versioning, and even people who stick strictly to a naming convention still get confused at times. Some applications append .bak or prefix ~ to create their own backups, and then occasionally an automatically-created TMP or $tmp$ file can really save the day, and so on. Then when it comes time to clean up and organise a filesystem, everyone hesitates. Am I really sure there is not useful work in each of those ten versions? Which ones do I need to keep? So, we usually keep them all. After all, storage is cheap. ...

In responding to a recent security problem I had to consider the idea of intent in computer software, so I looked to see what Margaret Hamilton ↗ has to say. Hamilton proved her ideas spectacularly during the first Apollo moon landing in 1969. A hardware failure generated unexpected errors ↗, but the software coped by running the highest-priority tasks despite the barrage of errors and prevented an abort just seconds before landing on the surface. ...

Not Before Time is a public broadcast facility built on existing technology. Not Before Time gives three strong guarantees that information: will not be readable before a certain future time was not sealed before a certain past date and time was not electronically signed before a certain time These support human rights, democracy and business. The second guarantee is a lower bound on sealing, not a creation date. A released NBT private key cannot be inside a package sealed before its release, although it can be added to old material later. The claim cannot be checked until the package opens; a priority claim needs the ciphertext published or independently anchored at the relevant time. ...

AI is slow, and Agentic AI ↗ is even slower. I develop an MCP server ↗ that generates PDF documents, and I work with the Agentic Perseverance Composition Engine daily. Tasks that take maybe 5 microseconds on an operating system (eg, does a file called Things-to-Do exist?) can take a million times longer, between 2 and 5 seconds, because each operation requires multiple round trips to a remote LLM (often with timeouts.) It’s a young, unstable stack, comparable in maturity to early MS DOS or the Apple ][. When AI gets hold of your data via an MCP server it can do interesting things, but it is not put together well. ...

The detail of the GDPR and its implied computer science contain a solution for sharing secrets according to law. This continues to be true in 2026, as the Digital Omnibus Regulation ↗ takes shape. Executive Summary The GDPR sets up a conflict in trust between companies in particular circumstances, which can only be resolved by using the automation of a cryptographic audit trail with particular properties as described below. Problem Statement Under the EU’s GDPR ↗ law virtually every company is a Controller, and virtually all Controllers use at least one Processor. When a Processor is engaged, the GDPR requires that a contract is signed with the very specific contents spelled out in clause 3 of Article 28. The GDPR requires that Controllers and Processors cooperate together in order to deliver data protection, and this cooperation needs to be very carefully managed to maintain the security and other guarantees that the GDPR also requires. That’s what this mandatory contract is intended to achieve. ...

When Linux was a Struggling Challenger 💡 Key Point This is a 2026 restoration of my (Dan Shearer’s) 1998-2001 guide, preserved at archive.org ↗. Links have been updated to point to the archives where possible. In 1999 I joined my first startup, Linuxcare in San Francisco. The Linuxcare story is a quintessential United States dot-com bubble narrative, featuring a famous venture capital fund, massive growth, a failed IPO, and a fancy new ex-IBM CEO resigning under a cloud. Founded in 1998, Linuxcare aimed to be the “0800 number for Linux”. So close! ...

The Fossil ↗ source code management system is the most fully-featured alternative to Git, and has decades of development and testing starting in 2007. After helping Fossil make some changes I now use Fossil for several projects. I also use Git extensively on various software forges (but not GitHub unless I must). Mercurial ↗ is actively maintained but has lost most of its mindshare since Mozilla ↗, Bitbucket and others migrated away, and is rarely chosen for new projects today. So it’s either Fossil or Git. ...

LumoSQL ↗ protects data on mobile phones and other computers using a new data storage technology which is highly compatible with most existing devices. The first part of this gives better robustness in the case of a powerloss or other crash, and at-rest encryption. Most apps have no encryption at all so this is a great improvement. With the second part of LumoSQL being developed now, the device owner decides who can read or change their data down to the level of individual rows if they choose. This decision continues to be enforced even after it has been copied off the phone to (for example) a bank or dating or insurance company for processing with their in-house database software. Today, device owners are rarely in control of the privacy of their own data, despite the many privacy laws. If a phone is separated from its owner, LumoSQL data rows cannot be read without the consent of either the phone owner or someone to whom the phone owner has granted access even if the phone has been unlocked. These controls are fine-grained, meaning different levels of permission can be granted. ...

I have an interest in non-electronic computers as an educational tool. An horologer is someone who makes mechanical clocks and watches, and horologers definitely don’t believe in electronics. That’s why I published Shearer, D. (2007). "Communication: A Request for Collaboration." Horological Journal, 149(12), p. 471., which sounds much fancier than the letter to the editor it was. Given I didn’t even know the British Horological Institute ↗ existed until a week prior it makes me very pleased. ...

Large Language Models are subject to the laws of physics in a bad way, because they use so much electricity and make so much heat. I was interested to learn about Landauer’s principle, which identifies the thermodynamic cost of information erasure, and Bennett’s work showing that computation can avoid erasure through logical reversibility. Together, they suggest physics might also help by greatly reducing the amount of power required by AI datacentres. That still leaves many, many AI problems including an economic bubble, but it would definitely help. ...