The HardSID 4U is a combination of a VST plugin and a hardware synthesizer unit based on the legendary SID (8580; 6582; 6581) chip (the heart of the C64 personal computer). The unit can drive up to four SID chips (any versions in any combination).

VSTi main features:

• 8000Hz update rate on all SID registers.
• Wave-in VSTi pin for routing 8000Hz signals to any SID registers. Example: playing another VSTi's sound on the volume register (drum sampler, guitar synth, anything...). No other SID synth can do this.
• Full automation of all VSTi parameters in your VST host.
• Advanced modulation for each oscillator (3x for each SID):
  • 8x8 Modulation Matrix with selectable sources, targets and amount (-100% to 100%).
  • 8 Modulation Source Combiners for advanced modulation.
  • 4 LFOs.
  • 4 Envelopes.
  • Table editor for value sequencing at up to 8000Hz speed.
• Selectable filter curve for driving the famous analog SID filters (logarithmic/linear for the 8580/6581).
• Up to four VSTi instances can run simultaneously (one for each SID).

About the hardware:

• Two CPUs and main memory.
• USB connection (compatible with both 2.0 & 1.1).
• Isochronous USB endpoint for low-latency audio.
• Support for up to four SID chips (6581/8580/6582 in any combination).
• Updateable firmware over USB.

Connectors:

• Four mono dry outputs for the best sound quality (2x stereo jacks).
• Mixed output for the easiest usage (1x stereo jack - mono signal).
• Four mono inputs for filtering external sources with SID filters (2x stereo jacks).
• USB connector for connecting the unit to a desktop PC or a Notebook.
• DC-in connector for connecting the power supply (1A@12VDC).