We heard of the following floppy solutions: 

	Lion Tracks Megafloppy (A4710)
	Route 66 studios (A4720)

Martin has documented how to replace an SY99 floppy drive.

The following company from Italy

Lion's Tracs S.r.l. - G.m.b.H.Via L. Zuegg, 54I-39012 MERANO (BZ) ItalyFax +39-473-220879

sells a product which is called MEGAFLOPPY. It's an external 120MB hard disk drive, accessable through 720K portions by a replacement for the built-in synthesizer floppy drive ("superslim floppy driver"). They used to have a nice homepage (used to be www.lionstracs.it/wwwlionfolder/0inglese/E-mf-index.html, now offline ) which listed a lot of synths supporting their extension. Please note that the SY99 Music Synthesizer is not listed on the site, but several people said that our synth is supported. Recent theory is that a customized version for the SY99 came later onto the market, when other synths were already listed. Anyway, you better check this before buying the drive.

The drive logic itself will be accessible through an additional floating display panel which needs to be connected to the front of the drive replacement. This display thing will let you choose the appropriate 720K part of the disk.

Route 66 Studios has replacement SY77/SY99 and V50 floppy drives.