ESP8266 Home Computer Hides Unexpected Gems

With a BASIC interpreter and free run throughout their hardware, home computers like the ZX Spectrum and Commodore 64 used to be a pervasive way to light that hacker fire. With the advent of cheap single board computers like the Raspberry Pi, devices purpose built to emulate these classic systems have become fairly commonplace. [uli] built a device in this vein called the BASIC Engine which is driven by a microcontroller and a handful of hardware peripherals. Like other examples it can be attached to a keyboard, programmed in a BASIC, play video and sound, etc. But digging into the BASIC Engine reveals that it’s similarity to other devices is only skin deep.

The current version of the BASIC Engine (“rev2”) lives in a Raspberry Pi 3 case for convenience. It has RCA connectors for NTSC or PAL video output and mono audio, plus a bank of headers to tap into GPIOs, connectors for a keyboard, and more. [uli] wanted to aim for extreme low cost so a relatively beefy board like a Raspberry Pi didn’t fit the bill, and we expect it was an enjoyable challenge. Instead its interpreter runs atop an ESP8266 but with the networking stack removed. [uli] was disheartened by how bloated even a “Hello world” program was and ripped it out, discovering that hidden beneath was a very powerful and disproportionately inexpensive general purpose microcontroller. The video is driven by a VS23S010, sold as a 1 Mbit parallel SRAM with a neat trick; it also includes a composite video controller!

The real treat here is [uli]’s history writeup of how the BASIC Engine came to be. We’d recommend brewing a cup of coffee and sitting down for a full read-through. The first version was inspired by the PlayPower project, which was repurposing clones of Nintendo’s Famicom (NES to Americans) game console to make low cost home computers, complete with keyboard and gamepad input. [uli] started out by building a custom cartridge for a particular Famicom clone that ran a BASIC interpreter but after showing it to disinterested adults the project was left fallow. Years later, [uli] was encouraged to pick up the project again, leading down a twisted rabbit hole to where we are today.

If you want to build a BASIC Engine for yourself, Gerbers and build instructions are available on the pages linked above.

Thanks for the tip [antibyte]!