Sony PCLK-MN20
Pre-netMD PC Link kit. Updated version of the PCLK-MN10 (Adds support for XP/2K/98/98SE/ME).
Connects to your PC with a USB cable, then connects to a compatible device using TOSLink (or analong 3.5mm if you prefer) and Control-A1 cables.
Transfers are one way, and are done in real time.
Content adapted from: PCLK-MN20 Minidisc.org Page