Version 2.4 of the Semi-Virtual Diskette (SVD) was created by a classic computing hobbyist named Eric and could be used on TRS 80 models, Apple II, TI 99/4a, and Heathkit computers to extend a modern PC serial port to emulate a diskette drive. Click image for larger view.
This particular unit had a blown power supply and 7805 voltage regulator when I got it. Fixed. A nice addition for re-creating archived diskettes to the machine in order to build new diskettes. I don't think that Eric still builds or supports this product anymore. Not sure how many were produced.