I've finally gotten far enough in my project to post some status. The task at hand is to capture (and maybe in the future write) data off of arcane disk formats. In the past I've used the catweasel card, but it is no longer supported, and isn't general purpose enough to support the needs of my current subject, the Compucolor II floppy disk.
I turned to the kryoflux card, but soon realized that I didn't like the API much, and I was going to have to build an adapter card, as the CCII floppy interface is nonstandard. Also, some of my past arcane disk decoder projects used an 8" drive, and I would need yet another adapter for those. Since I was going to build an adapter, why not go all in and build my own capture hardware.
So I bought my Papilio Pro and got to work. I wrote my own SDRAM controller, but then glommed on to Mike Field's (Hamster's) SDRAM design, before going back to my own. The FPGA work was actually the easy part. Once I was able to capture bits off the disk, I had to write a python script to decode the bits into sectors and tracks and whole disk images, to decode the file structure and detokenize BASIC programs and such. The python script has a mini-shell to allow me to interact with it, eg, if a disk has read errors, I can dump the contents of individual sectors, or ask for specific tracks to retry capture.
Anyway, I've posted a 5 minute youtube clip of my setup showing it at work. This is my first attempt at narrating a video and it could be better, but it is good enough for now.
I've used this system to capture about 250 disk images for the Compucolor II, and I may come into another large batch to process. PCBs should be showing up in a week or two, then I'm going to rewrite one of my old catweasel drivers (for the wang 2200 computer) to use this new system.