BASIC Engine. © Basicengine.org.
The BASIC Engine is an open-source single-board nanocomputer the size of a Raspberry Pi, with functions based on PCs from the late 80s and early 90s, that will tickle those who yearn for that time and all things retro. It connects to a monitor or a PAL/NTSC television screen with an RCA cable (forget about HDMI), and displays 508x240 pixels with a 256 colour palette. The BASIC Engine has connections for a PS/2 keyboard and a PlayStation controller. In terms of software, of note is the BASIC interpreter with a Commodore-type editor and an Infocom Z-Code interpreter. You can create fantastic old-school animations using sprites (up to 32 sprites with 32x32 pixels), and there’s about 63 KB worth of memory for programs. In terms of sound power, there’s a 5-bit digital audio, and a wavetable synthesizer based on SoundFont.
Unfortunately, you can’t actually buy this computer for now, but you can build one with about US$20 worth of components and a little soldering skill. A Gerber file is available on GitHub, which allows you to order the custom motherboard (US$4.90 from Smart Prototyping, among others).