Picture of very first prototype of LISY80, January 2008. It used an IO-Warriror 40 ( Code Mercenaries ) for USB, I2C and Switch-Matrix; PIC16F872 for the Displays and a
PCF8574 used as port Expander for the Driver board. The pinmame Software was running on an old Intel PC (486) which was connected via USB to the IO Warrior.
First PCB with a lot of PCF8574 port extenders
First PCB with Edge connectors
But it basically worked