The Apple II’s eight expansion slots on the motherboard were one of the most crucial features. These allowed consumers to add cards from Apple and several other vendors that immediately sprung up.

[Oliver] has been working in the area since 2021 with one [Glenn Jones], with the duo experimenting with connecting the versatile microcontroller directly to the slot bus of the Apple II.

These were often deployed in schools and by power users looking for added reliability when maxing out the Apple II expansion slots, a configuration that could increase temperatures due to the ...