Polyphony - Mono, Duo, 4-, 8-, and 16-voice polyphonic modes
Oscillators - 2 Oscillators with 13 waveforms (sawtooth, triangle,
square, Pulse, PWM, Full Organ, Harpsichord, Strong Lead, Double
Pulse, Gritty, User Wave 1, User Wave 2) plus Noise.
LFO - 1 LFO with 12 waveforms (square, triangle, sawtooth, patterns,
random, etc.) with multiple sync options
Filter - Two 12dB/oct analog filters which can be linked in series for
24dB/oct configuration. 9 filter types (2 Lowpass, 2 bandpass, 2
highpass, LP/BP, LP/HP, and BP/HP modes) with Drive, Cutoff, Q and
Separation and dedicated ADSR envelope.
VCA - 1 ADSR envelope for Amp plus multiple triggering options with
tempo and gate time controls
Keyboard - 54 Keys (switchable over 5-octave range) and retractable. 5
Keyboard Triggering modes. Programmable Velocity Response (Attack,
Release, Drive, Env 2 Peak).

system requirements:

Macintosh - VSTi for MacOS X / 9, Audio Unit for Mac OS X. Power Mac
G4 64Mb of RAM (128Mb from Mac OS 9) Mac OS 8.6 or higher VST
Instrument-compatible application such as Logic Audio or Cubase SX.

more info from this softsynth:
<http://www.vintagesynth.com/misc/imposcar.php>

Compatibility
Architecture: PPC PPC (Carbonized)

Macintosh - VSTi for MacOS X / 9, Audio Unit for Mac OS X. Power Mac
G4 64Mb of RAM (128Mb from Mac OS 9) Mac OS 8.6 or higher VST
Instrument-compatible application such as Logic Audio or Cubase SX.