“In this Instructable I am going to show how to build the second version of a simple retro style PC based on an ESP32 and few other components.
This PC runs a modified version of Tiny Basic, a simplified dialect of BASIC, and generates the output for a VGA monitor.
The resolution is 640x200 pixels, allowing 80x25 asci characters in 16 colors. It uses a PS2 keyboards, and the code can be saved on a micro SD. I have created a breadboard that included a VGA and PS2 port, as well as a piezo and an adaptor for the micro SD reader.
Some of the ESP32 I/O free pins can be directly driven by dedicated BASIC commands. Those pins are available through an extra connector and a RS232 port. This means that this PC can be also considered a stand-alone microcontroller that you can program directly in BASIC to control other devices (sensors, actuators, etc.), without the need of an external PC and IDE. When your code is ready, you can save it on the micro SD with the nameautorun.bas and, at the reset, it is executed automatically.
The customized Tiny Basic as many extra features, such as the possibility to use floating point numbers and arrays, many graphical and mathematical functions, timing functions and so on, as shown in the next step.”