Phonemark "Quick Data Drive" - info?, also WTD Commodore 15xx drive, info.

Hi all, A while ago I bought a rather unusual C64/VIC20 add-on - a "Quick Data Drive", presumably made by a company called Phonemark. After thumbing through the manual I found a few photos of the cartridges. From what I can gather, it's an early "stringy floppy" device that uses a cartridge filled with tape that's set in a continuous loop. The cartridges in the photos carry the branding "Entrepo". Now, the problem is, the manual mentions a "Master QOS Wafer" that contains the operating system for the drive - my drive is missing this. Also, I don't have any blank cartridges/wafers. For curiosity's sake, I removed the cover and noticed that it uses a BSR (what ever happened to them?) mechanism. After a quick search online, I found out that the Rotronics Wafadrive (sp?) uses a very similar, if not identical type of cartridge. Does anyone have a spare QOS cartridge and/or a few blanks they feel like parting with? I'm also trying to track down a Commodore 15xx disk drive - 5.25", 3.5", MFM, GCR, whatever, as long as it uses the Commodore serial bus. I'm also after any information on the Commodore serial disk drive interface. Ideally I'd like to use one of these drives for data storage. I was going to use a WesternDigital controller or a Super I/O chip and a floppy drive, but no-one seems to sell either "raw" FDCs or Super I/O ICs... MFM, GCR, I don't give a damn how it records the data on the disk. I've got a Mitsubishi 3.5" drive lying around gathering dust and I want to get it to do something useful! Thanks. -- Phil. philpem(a)dsl.pipex.com http://www.philpem.dsl.pipex.com/