Features of SwinSID X2:

- Two AVR cores for double performance (48 MIPS)
- Two SID chip emulation
- Nearly full software compability with SID
- 6 voices
- 2 oscillators per voice with adjustable phase and mixing mode
- 16 waveforms stored in flash ROM
- Exponental ADSR volume fades without envelope bug
- White noise generator with pitch regulation
- FM modulation between voices
- Hard sync modulation
- Built-in socket for optional SID chip
- Lowpass filter with self-oscillating resonance
- Standard 4 bit sample playback as 4th voice
- Extended sample playback mode (6 channels x 8 bit)
- 2x oversampling to minimize aliasing effect
- 16 bit mixing and output
- 31,25 KHz sampling rate

SwinSID module

About SwinSID

   SwinSID is a hardware replacement for legendary SID sound chip which was placed in every Commodore C64 computer. This hardware extension is designed as a module installed directly into the SID socket. It emulates the sound of the SID chip, but it is a lot more powerful and allows you experience the new dimension of C64 music. SwinSID can be used as a replacement for both old and new revisions of SID. It just emulates almost full register set of standardf SID, and almost all applications and hardware devices, which uses SID, should work properly. You must notice that SwinSID doesn't sounds 100% like real SID. Due to some design limitation it introduces low aliasing distortions, but in other way it has improvements from SID in different areas like better ADSR envelope handling and digital, fat and self-oscilating filter.
   The hardware desing of SID and SwinSID modules is different in almost every way. SwinSID is equipped with general purpose microprocessor with internal RAM and ROM. A programmable device like this has a big advantage - there is a possibility to upgrade firmware and to add new features or fixes without any hardware modification.
   SwinSID is based on wave table synth so, any waveform can be stored in memory and played back instead of generating only simple waves like SID does. The new mixing modes can also be used for even more rich sound. The polyphony was increased from only three to six channels with stereo panning and maintain compability with current SID2SID devices. In fact it emulates two independent SID chips!.
    SwinSID has a very simple design thanks to high speed programmable ATMEL AVR microcontroller running at 24MHz or 32MHz. This chip is about 30 times faster than C64's main processor 6510, that gives enough power for real-time audio generating, mixing and processing. Digital sound goes from AVR to high quality 16 bit stereo DAC. At the end of processing we have stereo analog output for external amplifier.

Micro SwinSID - improved and simplified SwinSID

    The Micro SwinSID uses a newer and faster microcontroller - ATMega88PA and smaller and easier to build PCB. Thanks to higher clock 32MHz speed it was possible to increade sampling frequency by 30% to 41,6KHz.   New layout doesn't require additional DAC - it uses two 1bit fast PWM to modulate audio quality and play back it with 16bit and 41,6KHz quality.

SwinSID X2 - Dual core SwinSID

    SwinSID X2 uses two ATMega8515 AVR MCUs thus it can emulate two SID chips with single board. This board is specially designed to use in C64 and emulate second sound chip at $d420 address. TDA1543 DAC is used to get stereo sound  - with single SID sound on each channel.  
    There is one firmware for dual and single core version thus the new firmware is also compatible with previous SwinSID SE board. DAC is now connected only to master core and plays its voices on left channel while slave voices on the right. Both AVRs runs with the same 24MHz integrated oscilator clock source which helps maintain stability under heavy overclocking. C64 data and addres buses of both MCUs are connected together and address decoder is used to split one CS signal into two AVRs (this requires access to external A5 addres line from C64 bus). AVR port E is used for synchronization and port A for data transfer between master and slave cores.

Features

    SwinSID has almost all features of original SID chip - simple waveforms, effects, filter and more. In dual core mode the polyphony was increased from standard 3 to 6 voices. There is new speciall mode to allow playing single voice with two different oscillators simultaneously and adjustable phase shift.
Soundcard has 8 various waveforms from classic shapes (pulse, sawtooth, sine) to complex and soft sounds.
If that's not enough, waveform output can be modulated by value of other oscillator resulting in simple FM synth. SwinSID can be also used for high quallity 8 bit stereo sample playback instead of generating waveforms. Two cores gives 12 channels of 8 bit stereo channels with hardware mixing and voilume control
Finally, there is 16 bit digital lowpass filter with adjustable cut-off frequency and strong resonance. The filter doesn't have true SID charasteristic, but it sounds more like 8580 than 6581 with 'C64 compatible' firmware.
The SwinSID waveforms was improved to match standard 8580 sound and new waves was added by using non standard waveform selection bits. That gives 8 new sounds maintaining compability with standards SID tunes.

MIDIBox

    In mid 2007 I have started to cooperate with Thorsten Klose (creator of the MIDIBox hardware platform) to use SwinSID as a SID replacement in his MIDIBox SID module. He built SwinSID prototype and did intensive tests to check if it is usable with his other MIDI hardware. During this tests I have made several firmware updates to meet requirements. With TK help (and his scope :) I was able to fix some critical timmings which i didn't realize until he found it. He also modified MIDIBox firmware to support new SwinSID features directly from his devices. Now you can use SwinSID not only as a SID replacement but also as a simple synthesizer with nice sets of features and oldschool sounding. The board laytout for MIDIBox  platform module with SwinSID is under development by MIDIBox community and for now only SID socket replacement is supported.

Thanks

    I would like to thank all people supporting Swin SID for testing, reporting bugs and etc. Special thanks goes to Thorsten Klose - for thorough testing and help fixing serious DAC problem and thanks for Crisp for firmware testing, SID recording demos and design of the new SwinSID X2 board layout.

For more info about SwinSID X2 and supporting it send me an e-mail