Archive for the ‘Technology’ Category
NANDputer: a computer built entirely from NAND gates
What is a NANDputer? It’s obviously a computer built entirely out of NAND gates. NAND logic (along with NOR) is functionally complete, so it is possible to construct all other logic gates using just NAND gates. But why? Well, like any good hardware hack: to see if it could be done.
Taking Kevin Horton nearly two months to design and make, every part of the build apart from the peripheral board is based on NAND gates (hence why the point-to-point wiring is…crazy). The basic architecture of the computer is fairly conventional, with an accumulator, a full ALU, 8 bit registers, separate RAM/ROM areas (Harvard architecture), instruction skipping for decision making, bit set/clearing, a three-level stack and even an interrupt.
It takes 96 clock cycles to run a single instruction, giving just over 100kIPS (thousands of instructions per second) with the clock running at 10MHz. Not great (roughly 2-3x slower than a Commodore 64 at 250-300kIPS), but not bad considering the hardware engineering. For example, it’s faster than a TMS1000!
The image below shows all of the NANDputer boards installed into the backplane; check out the images of the other PCBs, as well as the NANDputer running its first program.
(N.B. If you’re still curious about how a NAND-based computer works, then try this online course.)
Interview with ITWales
I was interviewed last month by ITWales, to talk about computer science education, CAS Wales, the Technocamps project and the future skills and expertise required to underpin the digital economy in Wales.
(full interview here)
Computing in education: Nellie the School Computer (1969)
A great clip from Tomorrow’s World, first broadcast in 1969, of Nellie: “a computer set to revolutionise the classroom“. In this clip, the boys of Forest Grammar School in Berkshire demonstrate how Nellie can be programmed to solve mathematical equations and play music, as well as the importance of computer maintenance…
Nellie was an Elliott 405, made by Elliott Brothers, one of the early UK computer companies (Tony Hoare worked there for eight years).
Woman’s Hour on BBC Radio 4: “Male Geeks Rise up for Women”
At present, only 30% of computing jobs are filled by women and when it comes to the number of female speakers at computer conferences, the figure is much, much smaller. In an attempt to address this problem, men are now signing an online pledge to boycott conferences where there are no women on the panel. But just how effective can this tactic be? Should men be doing more to get women and girls into computing? And does the problem really lie with conference organisers or in the fact that just not enough girls are taking computer studies at school? Jenni talks to Aral Balkan, a web designer, who has signed the pledge, to 13 year old Amy who loves computer programming and to Dr Tom Crick, Chair of Computing At School in Wales.
On Friday, I was a guest on BBC Radio 4′s Woman’s Hour, discussing females in IT, along with Aral Balkan and 13 year old Amy Mathers. As you can see above from the somewhat incongruous screenshot, the original focus of the programme had been on “male geeks rising up for women” (something with which I was not particularly comfortable), but I felt I had been invited on to discuss the educational aspects of the problem. As I’m sure you’ll agree, Amy was the stand-out star of the show, displaying an impressive understanding of computer science and the value of learning how to program.
Unfortunately, there has been an orchestrated social media backlash due to the choice of two male guests, which got picked up by the Daily Telegraph and the Daily Mail the following day. Without wanting to add to the furore, there appears to have been a lot of noise made with very little fact-checking, detracting from the focus on the underlying problem; I suggest you read Aral’s excellent blog post, as well as the response from the editor of Woman’s Hour.
Impact
It may have far-reaching significance in electronics and electrical communication…
Bell Labs press release on the transistor (1948)
Remembering the Atlas: the UK’s first supercomputer
An excellent post on the Google Europe blog describing the 50th anniversary of Atlas, the UK’s first supercomputer.
2012: A Space Odyssey
What if 2001: A Space Odyssey was set for release in 2012?
It would clearly be a nightmare to market, not fitting into any of the big audience demographics. But what if it was turned into a bone-crunching, non-stop science fiction explosion of action fit for blockbuster season, with plenty of smash cuts and drum’n'bass…?
(HT Film School Rejects)
Useful methods in Android 4.2: isUserAGoat()
android.os.UserManager, a new class added in Android 4.2 (Jelly Bean) which manages users and user details on a multi-user system, has exposed a very useful public method:
(source and an explanation)
