I mentioned in passing in a recent post that when I was helping teach first-year computer science students at the University of Edinburgh, I used to recommend that they bought a copy of The Ladybird Book of the Computer. Since Ladybird books were generally written for little kids, they thought I was joking. But I was serious. For students who had not experienced computers before—this was before the PC or even the Apple II so nobody had one at home—it was a great introduction.

Ladybird started in 1940 and produced nearly 650 titles. These days it is owned by Penguin. You can read the story in a 2017 Guardian article The Ladybird phenomenon: the publishing craze that's still flying.

All Ladybird Books have the same format, with text on the left-hand page and a picture on the right-hand page. They are all the same child-friendly size, with distinctive-looking covers. If you grew up in Britain, you would immediately recognize the format. That's one reason that it's latest venture, producing titles for adults, has worked so well. They seem to be in two different flavors. Some of them are retro-spoofs of the original children's books, such as The Ladybird Book of The Hangover, or How It Works: The Husband. But some are more like the computer book above, serious attempts to provide an introduction to difficult topics, without being in the least bit patronizing. The first book they produced in 2017 was on quantum mechanics, so I wasn't joking in the title of this post. There's also one on artificial intelligence.

The Ladybird Book of the Computer

What I remember as The Ladybird Book of the Computer is actually called How It Works...The Computer, A Ladybird Book. As it happens, the whole 1971 edition of the book has been scanned and is available online.

There are a few pages of the 1978 version of the same book on BoingBoing, although decorated with trying-too-hard humorous annotations.

I picked an example page below about ferrite core memory since you have to be what is tactfully called "a certain age" to have actually used core memory. If you ever learned to program in C or C++, I'm sure you've received the message "Segmentation fault (core dumped)" when you messed up, despite computers not using core memory since the end of the 1970s. But even so, you might not have a clue how it actually worked.

It relied on magnetic hysteresis, that a large current can change the magnetization of a core, but a much smaller current doesn't have a smaller effect—it has no effect. This means that a large current can be used for writing, and a small current can be used for reading, without the read being destructive.

They were surprisingly fast. As it says at the bottom of the page, computers using magnetic core memory could "run at a million additions per second", or 1 MIPS (and yes, the S is required, since it is not a plural, it is "per second"). The Interdata computers that I worked on for my PhD creating both a file-server and a client diskless operating system that used it, all used magnetic core memory and ran at 1 MIPS.

Here's a photo of an earlier 1956 generation of core memory that I took at the Computer History Museum in Mountain View. This took 5us to access, and the cores were 1/16" and cost $1 per bit. Eventually, according to the CHM, they took 0.5us to access and were 1¢ per bit. Today, an 8GB DIMM takes about 100ns to access and costs about $50. So now a megabyte costs less than 1¢. But note that speed. A modern DIMM takes 0.1us to access, only 5 times faster than at the end of the magnetic core era 40 years ago. Our computers run a lot faster despite memory having increased in speed only about 4 times since the Mostek 4K DRAM with a 400ns access time around the time we started to make the transition from core memory to semiconductor memory.

Here's another page from the book, this time describing how a processor executes instructions. You would hardly have to change a word to describe how a modern semiconductor microcontroller works. It is pretty much the model that software engineers have of how microprocessors work too, even though under the hood the implementation is actually much more complex.

The Ladybird Book of Quantum Mechanics

As I said above, a couple of years ago, Ladybird started to produce some books for adults. Some are more like the computer book above, serious attempts to provide an introduction to difficult topics. The first book they produced like this is on Quantum Mechanics. Of course, I immediately went on Amazon and ordered it.

It is like the computer book, in that I don't know of a better concise introduction to quantum mechanics. It's written by Jim Al-Khalili, a physicist at the University of Surrey (that's just outside London). Apart from writing this book, he's obviously a good popularizer, having received the inaugural Stephen Hawking Medal for Science Communication three years ago.

The quantum mechanics book covers classical physics, the birth of quantum theory, wave-particle duality, the Schrödinger wave equation, the Heisenberg uncertainty principle, antimatter, Schrödinger's cat, Feynmann's quantum field theory, quantum computing, the many worlds interpretation, quantum gravity, and more. All in 23 pages of text and 23 pages of graphics/images.

As someone whose job is to write clearly about complex technical topics, I'm impressed.

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