CAST Release 1.13 is a publically-available version of the CAST synthesis system. The synth program, demosoftcast, is for SGI workstations running IRIX 5.3 and up. You should read about the license and restrictions for this software.
Click here for instructions on downloading and installing CAST release 1.13 on your SGI machine. Contact Adrian Freed directly for information regarding the high performance option for softcast that uses IRCAM's FFT-1 technique.