Embedded Linux on a 2-Layer Board!
For my first shot at creating a fork-ready design, I created Clementine Core — a 454 MHz ARM single-board computer with 64 MB of RAM, designed to boot Linux from a MicroSD card. Clementine Core uses the circa-2009 Freescale i.MX233 application processor, which, while getting a bit crusty, is still widely-available for less than $10/each and is guaranteed to be in production until at least 2019. This processor was selected because of its high level of integration — nothing other than external RAM and flash storage is required for it to boot into a full Linux environment. The i.MX233 also is available in a TQFP package, which allows the design to be laid out on a two-layer PCB and hand-soldered.