In the years since this site was first launched (in February of 1999), many Chroma owners have gotten in touch, subscribed to the mailing list, "registered" their instruments, and contributed to the site; many others have become Chroma owners, sometimes inspired by this community. (See also Classified Ads for instruments for sale and wanted.)
A kind of historical record, the registry contains entries for known Chromas (models 2101, 2102, 2103, 2104, and other/unknown) and Chroma Expanders (1631, 1633), their owners, and their stories. This is the real history of the instrument: the musicians who play it, the music they have made, and the anecdotes that give each Chroma its own personality. There are now over 200 instruments listed, which sounds impressive but is a small number when compared to the number of Chromas produced (which is somewhere between 1000 and 3000, depending on whom one believes--see How many Chromas were manufactured? in the FAQ and for more on this debate). If you have a Chroma that is not yet listed, please get in touch and send in some information on your instrument.
The mailing list started in June of 1999 and has been going strong ever since. There are over 100 subscribers who discuss all manner of technical and historical issues surrounding the instrument, its use, troubleshooting, and repair. Join us!
The ChromaTalk mailing list archives contain each thread and message posted to the list since its inception. (The graphs indicate list activity, month by month, for each year.) Archives are posted at the end of each month. They are an invaluable record, especially in terms of troubleshooting information. The links at left group the archives by year; an overview page for each year highlights some of the more interesting posts and threads.
The Chroma Cult was a club for Chroma owners run by Ken Ypparila  (supplier of the Syntech MIDI retrofit to this day), which compiled patches from members (see Patch Downloads) and offered memory upgrades.