Dr. Scott M. Baker wrote an article detailing how he turned a Raspberry Pi into a virtual storage device for ISA bus computers:
I’m tired of carrying compact flash cards and/or floppies back and forth to my XT computer. I like to do development at my desk using my modern windows PC. While I can certainly use a KVM switch to interact with the retro computer from my Windows desktop, it would be a lot more convenient if I could also have a shared filesystem. There are several alternatives, from serial port solutions, to network adapters. However, I wanted something that would emulate a simple disk device, like a floppy drive, something I could even boot off of, so I implemented a virtual floppy served from a Raspberry pi.
See the full post on his blog here.
Check out the video after the break.