Its kind of hard to tell without knowing what kind of connector the MD itself has. Aiwa is a subsid of Sony now, so im inclined to believe its a “Mini USB Version 2.0”, the type Sony most commonly uses on its digicams. You can also get this cable by looking for a PSP accessory usb cable at your local electronics store. Take a look at this guide for pictures:
http://www.ramelectronics.net/html/usb_minicables.html