Amazing what some had already developed... it's a silicon floppy which can emulate even disk drives for an Apple II, but also for unusual disk formats like the TRS-80 SD/DD mixed ones.

Just take a look at
http://www.thesvd.com/svd/index.php

It doesn't look very expressive, but it is !

Inside, a PIC 16C74 processor will do the job.
It will be connected with the help of a RS232 interface.
Windows and Linux is supported from PC side.
And it can be build by yourself as a "kit".