John Graham-Cumming

Doron Swade's 2003 PhD thesis entitled "Calculation and Tabulation in the Nineteenth Century: Airy versus Babbage" is available for download.

It covers the interaction between Charles Babbage and George Airy and shines light on a relationship that has previously been reduced to caricatures of the two men.

I came across a wonderful video of Grace Hopper (if you don't know who she is go read that Wikipedia article first and the come back here) explaining what a nanosecond is using a visual aid. The aid is a length of wire equal to the distance light travels in one nanosecond. That's 299.8mm (or as she puts it 11.8").


That's a handy length because it fits neatly on A4 and US Letter paper. So, here are downloadable nanoseconds that can be used to make the same point as Hopper. I've prepared both A4 and US Letter versions as PDFs.

Seeing the distance light travels in a nanosecond is interesting because it becomes clear that at the very high frequencies that computers operate at the speed of light and length of cabling become significant. This propagation delay is something that designers of very high speed circuits have to take into account. For example, a machine working 1 GHz has a clock that's ticking once every nanosecond.

Here are the two versions.

Plan 28's donation system is now online through JustGiving. Donations can be made in British Pounds, US Dollars, Euros and a number of other currencies. As a UK charity Plan 28 is eligible for GiftAid; tax payers in the UK can help the charity by signing the GiftAid form when they make a donation.

As Plan 28 is a very long project it is particularly helpful when we receive regular donations. The donation system is able to set up monthly donations for people who want to contribute a little each month over the long term.

Plan 28 can accept donations on the web or via mobile phone. For example, to donate £10 by phone text BABB37 £10 to 70070.

There are a number of projects that allow one to control an Arduino using node.js.  For example, there's Noduino and Johnny-Five. To my mind these things are an abomination(*) because they are teaching people to use Arduino at the wrong level of abstraction. If you are going to learn Arduino, learn some C.

One can always argue that they get more people using Arduino, but all these people would be better off learning some C for the joy of Arduino is not (to my mind) controlling it using a massive desktop or laptop machine. The joy of Arduino is small, embedded projects that do stuff. Such as Simonoids:
And if they learn some C they'll get more out of Arduino because they'll be able to do things that the node.js layers don't allow: cool stuff. And once they've learnt some C and need to control the Arduino from the host they'll be able to do even more cool stuff. If you are going to learn Arduino, learn some C.

To get an idea of what's problematic about '…

The story of a Big Data problem in 1955 presented at StrataConf London 2012.


As soon as I have Tim Greening-Jackson's permission to share his research paper on "LEO 1 and the BR Job" I will update this blog post with information on how to get it.

PS Tim has kindly given permission to post his paper here.

It's no secret that I wasn't impressed by George Dyson's book "Turing's Cathedral" because it skewed history in a particular way a bit too much, and I felt that the title exploited the Turing anniversary. But I was struck by something he said in a StrataConf EU keynote.

He said that in 1953 there were only 53 kilobytes of random-access memory in computers in use and showed a picture of a February 1953 report entitled "A Survey of Automatic Digital Computers" published by the US Office of Naval Research. I thought that sounded odd, so I tracked down a copy of the report.


In fact, he makes the same claim in the book, but I'd overlooked it:


So, I started going through the report looking at machines that were operational in March 1953 according to the report. Just concentrating on binary machines I quickly found that random-access memory was well past 53KB.  By the time you reach E (the machines are in alphabetical order) there were 85,856 bytes of…