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)
Farnham
To celebrate Douglas Adams‘ 61st birthday, please enjoy this little gem from The Meaning of Liff:
FARNHAM (n.)
The feeling you get about four o’clock in the afternoon when you haven’t got enough done.
(see also: Deadlines)
2013 University Guides: Computer Science
With the impending start of the 2014 university guide season, here’s an aggregation of the four main UK university guides in 2013 for Computer Science:
- The Complete University Guide 2013 (April 2012)
- The Guardian University Guide 2013 (May 2012)
- The Times Good University Guide 2013 (June 2012)
- The Sunday Times University Guide 2013 (September 2012)
We’ve sold Computer Science, now we have to sell what it means to be a Computer Scientist…
Last week was an exceptional week for computer science education in the UK: Google donating 15,000 Raspberry Pis to UK schoolchildren, Microsoft calling for computer science to be taught from primary school, the Department for Education including computer science in the EBacc as the “fourth science” and UCAS 2013 entry statistics showing the highest increase in total applications for Computer Sciences (up 12.3%). This follows on from the launch of the CAS Network of Computer Science Teaching Excellence in September, the publication in November of the draft ICT Programme of Study for England and the announcement in January of a review of the ICT curriculum in Wales, reporting back in June.
So it appears we’ve sold the rigorous academic discipline of computer science; but not to simply increase the supply of programmers for the IT industry or to get more people to study computer science at university — the rationale has always been based upon computer science being of wider educational value to everyone, in the same way as we value physics and mathematics. But after a discussion with Pete Yeomans (@ethinking) at the CAS fringe event at Bett 2013 last week, it appears that we are now facing a more subtle and refined challenge:
We need to do more than ‘sell’ computer science as a discipline…we need to sell what it feels like to be/think like a computer scientist.
— Dr Tom Crick (@DrTomCrick) January 31, 2013
This is the real marketing challenge: to truly change the wider perception of the discipline, we now have to sell what it really means to be a computer scientist, how to think like a computer scientist and the universal potential of this mindset.
And everyone needs to understand and value this.
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).
