Raspberry Pi A User Manual page 22

6
R A S P B E R R Y P I
U S E R G U I D E , S E C O N D E D I T I O N
The next morning, Rory's video had gone viral, and I realised that we had accidentally prom-
ised the world that we'd make everybody a $25 computer.
While Rory went off to write another blog post on exactly what it is that makes a video go
viral, we went off to put our thinking caps on. That original, thumb-drive-sized prototype
didn't fit the bill: with the camera included as standard, it was way too expensive to meet the
cost model we'd suggested (the $25 figure came from my statement to the BBC that the
Raspberry Pi should cost around the same as a text book, and is a splendid demonstration of
the fact that I had no idea how much text books cost these days), and the tiny prototype
model didn't have enough room around its periphery for all the ports we needed to make it
as useable as we wanted it to be. So we spent a year working on engineering the board to
lower cost as much as possible while retaining all the features we wanted (engineering cost
down is a harder job than you might think), and to get the Raspberry Pi as useable as possible
for people who might not be able to afford much in the way of peripherals.
We knew we wanted the Raspberry Pi to be used with TVs at home, just like the ZX Spectrum
in the 1980s, saving the user the cost of a monitor. But not everybody has access to an
HDMI television, so we added a composite port to make the Raspberry Pi work with an old
cathode-ray television instead since SD cards are cheap and easy to find. We decided against
microSD as the storage medium, because the little fingernail-sized cards are so flimsy in the
hands of children and so easy to lose. And we went through several iterations of power sup-
ply, ending up with a micro USB cable. Recently, micro USB became the standard charger
cable for mobile telephones across the EU (and it's becoming the standard everywhere),
which means the cables are becoming more and more ubiquitous, and in many cases, people
already have them at home.
By the end of 2011, with a projected February release date, it was becoming obvious to us
that things were moving faster, and demand was higher, than we were ever going to be able
to cope with. The initial launch was always aimed at developers, with the educational launch
planned for later in 2012. We had a small number of very dedicated volunteers, but we
needed the wider Linux community to help us prepare a software stack and iron out any
early-life niggles with the board before releasing into the educational market. We had enough
capital in the Foundation to buy the parts for and build 10,000 Raspberry Pis over a period
of a month or so, and we thought that the people in the community who would be interested
in an early board would come to around that number. Fortunately and unfortunately, we'd
been really successful in building a big online community around the device, and interest
wasn't limited to the UK, or to the educational market. Ten thousand was looking less and
less realistic.