TTS-1 can use the extended instrument set available in General Midi 2 (GM2). Below is a pdf file that explains in detail the capabilities of the multi-timbrel TTS-1 soft synth. The synth is still remarkably versatile and unique to have been first released in 2004.
It is not a VST though. It's actually a DX instrument. Band-in-a-Box, RealBand and Cakewalk by BandLab support DX instruments so those programs can use it but some programs, Audacity for example, don't support DX use.
The VSC or
Virtual
Sound
Canvas is similar to TTS-1 but there are some differences. VSC was a Roland product while TTS-1 was a product Roland made for Sonar's parent company. While both use samples to create their instrument sounds the VSC sounds emulate sounds from the Roland Sound Canvas series of hardware products while the TTS-1 has it's own, unique instrument sounds. TTS-1 was briefly released as a boxed, standalone Cakewalk VST product. Finally VSC was only released as a 32 bit DX instrument while TTS-1 has both 32 and 64 bit varieties.
Description: Using the TTS-1 Soft Synth pdf file.
Description: Piano Selections Screenshot