The BASIC Engine is a very low-cost single-board home computer with advanced 2D color graphics and sound capabilities, roughly comparable to late-1980s or early-1990s computers and video game consoles. It can be built at home without special skills or tools and using readily available components for under 10 Euros in parts, or mass-produced for even less.

Hardware

• ESP12-E/F module with ESP8266 SoC and 4 MB flash memory
• VS23S010 video controller with 128k VRAM and composite video output in PAL or NTSC
• 5-bit PCM sound from I2S controller
• MicroSD card slot
• PS/2 and PS/2-compatible USB keyboard interface
• PlayStation controller port
• PCF8575 I/O extender with 16 GPIO pins
• I2C and SPI busses on I/O expansion connector
• power supplied via Micro-USB socket or pin header
• RCA connectors for video and audio

Software

This firmware contains a basic operating system and BASIC interpreter ("Engine BASIC") that allows the BASIC Engine to be used as a stand-alone computer programmable in the BASIC language. It provides easy access to the hardware’s capabilities as well as numerous other features.

Graphics and sound

• 256-color text and graphics at resolutions from 160x200 up to 460x224 (PAL: 508x240) pixels
• Software sprites (up to 32 sprites sized up to 32x32 pixels).
• Scrollable tiled background graphics engine with up to four layers.
• Wavetable synthesizer and PLAY command that renders music in MML format.
• Loading and saving of PCX image files to and from video memory.
• Various text fonts built-in, including an ATI 6x8 font (for up to 76 (PAL: 84) characters per line) and PETSCII.
• Direct manipulation of video memory and controller registers possible, permitting higher-color screen modes, custom resolutions and other video effects.

Special BASIC language features

• Structured programming constructs (DO/LOOP, WHILE/WEND, IF/THEN/ELSE/ENDIF blocks).
• Labels and named procedures with local variables.
• Numbers are double-precision floating point.
• String and numeric list types (particularly useful for game programming).
• Escape codes for PRINT, similar to the control characters in Commodore BASIC.
• Event handlers (sprite collision, end-of-music, errors, game controller input).

Development features

• "Screen editor" similar to Commodore BASIC, allowing direct manipulation of on-screen code and commands, while also permitting scrolling within the program in memory.
• Syntax highlighting and automatic indentation in LIST command.
• Loading of programs with or without line numbers.

Hardware support

• ESP8266 CPU core running at 160 MHz, ca. 63kB free memory for BASIC applications.
• Files can be stored on FAT32 file systems with long file names on MicroSD card as well as the internal flash memory.
• PlayStation controller support.
• Support for PS/2 and PS/2-compatible USB keyboards (US, Japanese and German layouts supported).
• Access to custom hardware add-ons via the 16-pin GPIO extender or I2C bus.

Network support

• Separate build that provides networking capabilities (cannot be used with tiled BG/sprites and wavetable synthesizer due to resource constraints; both builds can, however, be installed in flash at the same time)

Other features

• Z-code interpreter for playing interactive fiction games.
• ASCII text editor.
• Firmware update from SD card.
• Customizable color scheme, start-up screen mode and font..
• Switchable video luminance filter provides sharp high-contrast graphics on LCD screens when turned off and avoids color artifacts on old CRT screens when turned on.
• Automated test suite adapted from Bywater BASIC.

PCB Errata

Revision 2 of the PCB contains one error:

R6 value is given as "22R", should be "75R".

Revision 1 of the PCB contains two errors:

R6 value is given as "22R", should be "75R".

C3 and C4 values are given as "10p", should be "56p".

Firmware binaries

Binaries are available on Github in the firmware repository. They can be uploaded to the system via the serial port, using esptool:

esptool -cd ck -cb 921600 -cp /dev/ttyUSB0 -ca 0 -cf ttbasic-<version>.bin

If a version of Engine BASIC is already installed, the firmware can be updated from SD card using the command

FLASH "ttbasic-<version>.bin"

If you are interested in the latest features, you can also download nightly builds of the current Git master branch. The files called basicengine-firmware-default-... contain the default firmware (recommended), while the files called basicengine-firmware-net-... contain the network-enabled build.

Sound font

The sound font file 1mgm.sf2 must be copied to the SD card or the internal flash memory for wavetable synthesizer sound to work.

Expansion connector pinout

Schematics

PDF

Project page:

https://basicengine.org/

https://github.com/uli/basicengine-pcb