Pre-netMD PC Link kit. Connect to your PC with a serial cable, then connect it to the compatible device using the analog 3.5mm connector and Control-A1 cables. Compatible with Windows95 and Macintosh with Kanjitalk 7.1 (not compatible with PowerPC G3 models). Software appears to be named 'MD Editor.' If anyone has a copy let us know.

Unlikely to be supported on any modern OS.

Partial Compatibility Chart

Content adapted from: PCLK-MD1/PCLK-MD2 Minidisc.org Page Sony Press Release