This is where we will keep a list of great little computers to put to use doing real science.
Raspberry Pi Zero Business-card size computer running Linux. 1 GHz, 512 MB RAM, mini-HDMI, 2 micro-USB ports (one for power), micro-SD slot (microSD card required). $5.
Chip Business-card size computer running Linux. 1 GHz, 4GB flash, 512 MB RAM, HDMI, VGA, 1 USB 2.0 port, WiFi, Bluetooth. $9. HDMI adapter separate for extra $15.
Orange Pi A tiny quad-core computer (deck of cards size) that runs Linux. 1.6 GHz, 1 Gig RAM, HDMI, 3 USB2.0 ports, 100 Mbps Ethernet port, camera interface, 40 pin (Raspberry Pi compatible) header, TF memory card slot (memory card required (up to 64GB)). $25.16. Or $13.77 from China.
Unwired One (formerly Black Swift) A postage-stamp size computer running Linux (OpenWRT). 400 MHz 32-bit MIPS, 64 MB RAM, 16 MB flash, 2 micro-USB ports (one for power), WiFi, 2 100 Mbps Ethernet ports.
pcDuino Lite WiFi Credit card size computer running Linux. 1 GHz, 2 GB flash, Tf card slot (for another 32 GB), HDMI, USB2.0 port, WiFi. $29.
Raspberry Pi 2 Model B Deck of cards size computer running Linux. 900 MHz, 100 Mbps Ethernet, four USB2.0 slots, HDMI, 1 Gig RAM, camera interface, 40 pin header, memory card slot (microSD card required). $37.99.
Banana Pi M2 Quad-core Pi clone running Linux. 1 GHz, 1 GB RAM, Gigabit Ethernet, WiFi, HDMI, 4 USB 2.0 ports, Tf card slot (64 GB max), camera port. $44.99.
Raspberry Pi 3 Model B Quad-core deck of cards size computer running Linux. 1.2 GHz, 100 Mbps Ethernet, four USB2.0 slots, HDMI, 1 Gig RAM, camera interface, 40 pin header, memory card slot (microSD card required), WiFi, Bluetooth. $53.94.
Beaglebone Black - Rev C A deck of card size computer running Linux. 1 GHz, 4 GB flash, micro-HDMI port, 2 USB 2.0 ports, 100 Mbps Ethernet, 2 46 pin headers, 2 32 bit microcontrollers (in addition to main CPU), GPU, floating point accelerator. $54.95.
LattePanda A tiny quad-core computer (deck of cards size) that runs Windows 10. 1.8 GHz, 2 or 4 Gigs RAM, 32 or 64 Gigs SSD, WiFi, HDMI, Bluetooth, USB3.0 and an onboard Arduino second processor. $89.