When Apple designed the Super Serial Card back in 1981, they made it compatible with SRAM chips, replacing the ROM it shipped with. Modern EEPROM look just like SRAM chips, with a longer write cycle, so I popped one in, added a write-protect switch, and off I go to debug the Apple II Pi PiDrive ROM code.
Rodney’s H/W arrived and it fired right up. Made some firmware updates, optimized the sketch, and we have a reasonable perky SDCard storage for the Apple II. I re-christened PiDrive to SiDrive: Serial Interface Drive.
Kevin Dady’s website that Rodney based his design on: http://osgeld.a2hq.com