I want a single device that can be plugged into the A500, A600, A1000, A1200, A2000, A2500, A3000, and A4000.... and the CD-32 (via one of the expansion boxes that were created for it). The only options would be floppy port or parallel port, since that is the only interface that is in common with all Amiga models.
I will make images of my DAT tapes when my SCSI<>CF adapter arrives. Thanks for the link.
The fast PIC24 micros would require level conversion and a voltage regulation circuit for the 3.3v needed by the PIC and SD card. The PIC24 has DMA so it can handle the SPI port for the SD card, and allow asynchronous fetching/putting data via the parallel port. It could actually be pretty fast without tieing up the machine.