cynthCART64 V2.0.1

From the official cynthCART website:

Cynthcart is a cartridge for the Commodore 64/128 that turns the computer into a standalone analog synthesizer. Cynthcart's key-command user interface allows it to be played and controlled without a monitor, making it especially suitable for live performance. The original Commodore 64 piano keyboard overlay can be used, and Datel, Passport, Sequential, and Kerberos MIDI interface cartridges are now supported.

FEATURES (version 2.0)
+ 30 preset sound patches
+ Arpeggiator, portamento, vibrato, and tremolo effects
+ Analog filter control and effects
+ Control of attack, release, and other sound parameters
+ MIDI support including pitch bend, patch changes, and controllers
+ On-screen help
+ Color visualizer display
+ Mono stack, 3-voice mode, and 6-voice mode (with second SID)
+ No latency
+ SID hex editor for advanced users
+ Ability to turn off video chip to reduce noise
+ PAL and NTSC pitch tables with automatic selection
+ Copies itself to RAM (cartridge can be removed after booting)

SUPPORTED ACCESSORIES:
+ Commodore 64 piano keyboard overlay
+ Datel, Passport, Sequential, and Kerberos MIDI interface cartridges
+ Paddle controllers in port 2 for filter, pulse width, vibrato, and pitch
+ 2nd SID chip for stereo and 6-voice sound
+ REU

All cynthCARTs that you order through Protovision are orange.