Building SIO2Arduino to enable an Atari 800XL to use SD Cards

Last winter, I built an SIO2Arduino circuit - it is an adapter, that enables the Atari to use disk images loaded on to a regular SD card.

To the Atari, the SD card works just like a floppy drive.  It’s was built following the instructions found here: http://whizzosoftware.com/sio2arduino/

With a program called SDRIVE, I can select a disk image on the SD card, and then load it:

I never did get the adapter working perfectly - I can load certain disk images, such as ballblazer, but not others, like Karateka.  I think it would take a lot more investigation, and perhaps digging into code, to figure out how to fix this issue.

Until I get a suitable TV, this is likely as far as I’m taking this particular project.