Making an Arduino shield can be simpler than you think. This time I designed one to program Attiny and Atmega microcontrollers, that way I don't have to use a breadboard and make the wiring to ...

There are a few options to do similar things with PCB layout, including tscircuit. There’s a walk-through for using it to create an LED matrix and you can even try it out online, if you like.

The Arduino Uno-compatible board has an MCS-51 (often called 8051 instead) instead of the usual ATmega328P/ATmega168. Specifically, [ElectroBoy] uses the AT89S52.