Ok, so let's talk cheap and tiny: programmable computers needn't be large precious things, they can be tiny things that we can leave behind, let go, abandon to the cruel world. I'm not advocating being overly irresponsible or wasteful, but I do think that the world and the things that you can make in it gets a lot more interesting if you don't have to worry inordinately about protecting your project. An Arduino or Raspberry Pi, wonderful tools that they are, are not cheap, somewhat demanding of battery life, and as such we usually need to protect our controller and modify our project to fit their form factors. As a teacher, I can't count the number of times I've seen an Arduino used to listen for a button press or wait for a door to open.

Wouldn't it would be nice to have something small, programmable, cheap, and power efficient that could do some of what an Arduino can do and had the same easy tools to use with it? Well there is: the ATTiny85! In the DIP configuration, that is, with the little breadboardable pins that we're used to working with like the one that's shown here, the ATTiny85 (which I'm going to call the Tiny85 from here on out) is about 9mm x 9mm, can be programmed using the Arduino IDE, runs on as low as 3.3V at pretty tiny amperages (think watch batteries), and can be bought for around $0.70USD (picture courtesy of SparkFun).