The Olduino is a retro-Arduino. It uses an RCA 1802 processor from the 1970s but adds hardware and software so it can function like an arduino and use some arduino add-on shields. ... The Olduino has hardware support for high speed SPI(Serial Peripheral Interface) through a set of shift registers on the olduino board. It can do high-speed serial communications to an attached PC through an onboard AVR slave processor.