1994 seems to be when it started, Hal. At least that's the first Roland Atelier review that appeared in Keyboard Player in September that year - the AT70 flagship.
This comes from Sound on Sound Magazine's free on-line archive, so it's © to them!
...founder Ikutaro Kakehashi admits that he views the organ as the "most complete musical instrument". Despite this, or maybe because of it, the first of Roland's home organs, the Atelier AT70, was a strange hybrid of ideas. For example, its lower manual was 76-notes wide, was velocity-sensitive, and responded to a piano-style damper pedal. Unlike traditional organs, the Atelier also offered many of the rhythm and accompaniment features found on Roland's E-series accompaniment keyboards, and it even accepted Roland's existing Style cards. In addition, it included a 40,000-note sequencer. However, it didn't incorporate some expected organ facilities such as drawbars, and its sound-editing capabilities were decidedly limited. Nonetheless, there was no mistaking that the complete package was a large home organ, and it certainly packed a punch: a 240W punch, to be precise.
The AT70 (which cost a hair under £10,000) and its more affordable little brother the AT50 may not have been the most successful of Roland's instruments, but they were to spawn a dynasty that would become highly respected in its field. The initial range was fleshed out by the AT30 and the huge AT90 in 1996, and then the AT80 in 1997. There were no fewer than four new models in 1999 (the AT20R, AT60R, AT80R, and AT90R) followed by the introduction of the current range two years later. There are now seven of these: the AT10S, AT20S, AT60S, AT80S and the mighty 256-voice AT90S models that appeared in 2001; plus the AT15 and the baby of the range, the single-manual AT5 launched the following year.