MOS Technology SID

A 6581 SID chip on a C64 mainboard

Block diagram of the MOS Technology SID (6581/6582)

The MOS Technology SID ( SID stands for S ound I nterface D evice , German sound interface device ) is a programmable 3-voice sound chip , which was mainly used in the home computers C64 and C128 from Commodore in the 1980s .

It is considered to be the best sound chip of the 8-bit era. In 1995 Byte Magazine listed it in a list of the 20 most important chips in computer history. In 2019 he was inducted into the IEEE Spectrum Chip Hall of Fame. The SID was developed by Bob Yannes , who later founded the Ensoniq company. The SID is jointly responsible for the typical polyphonic sounds that shaped the home computer age.

Technical characteristics

• Hybrid chip, partly digital , partly analog
• 3 independent voices (oscillators)
• 4 partially combinable digital waveforms per voice (triangle, sawtooth, rectangle with adjustable pulse width, white noise )
• Fundamental frequencies from 0 to 4 kHz
• High resolution of the basic frequency of 16 bits
• 3 combinable analog filters ( low-pass , high-pass , band-pass or notch filter with an 11-bit cut-off frequency and variable resonance with 4-bit resolution, individually switchable for each voice, 2-pole filter)
• Digitally adjustable envelope for each voice ( ADSR )
• Individual volume control for all voices in 16 levels
• For each voice individually switchable digital synchronization of the voice with the next one
• Digital ring modulation of triangular waves with the next voice can be switched on individually for each voice
• Voice 3 can be suppressed at the exit
• 4. Voice by playing samples via volume register
• 5. Voice by multiplexing tones
• An external analog voice can be added and filtered
• Random generator
• 2 simple A / D converters
• 28 pin DIL housing

Versions

There are two versions of the SID, the older 6581 and the newer, HMOS -II version 8580 or 6582. The 8580 is primarily characterized by clearer sound with less interference, but the playback method often used on the 6581 works of 4-bit samples via the volume register no longer here. This can be compensated for by soldering on a resistor (≈750 kΩ). This modification is called a Digifix. Another difference is in the filters. While the properties of the filter in the 8580 largely correspond to the specifications, the filter in the 6581 exhibits strong non-linearities that vary greatly from chip to chip. Each 6581 has an individual sound. The 6581 was manufactured in 5 different revisions.

SID chips with the label 6582 were never sold in a C64 or C128, but were sometimes used as replacements for defective 8580s. The 6582 is absolutely identical to the 8580 and just has a different label. The 8580 requires an operating voltage of 9 V, in contrast to the older 6581, which requires 12 V.

Replicas and emulations

Hardware SID systems

There are some hardware synthesizers with real SID chips for sound generation:

The SIDPLAY software supports a PCI card ( HardSID ) with an original SID as a sound generator.

Another independent development is the StereoSID. Two SIDs are controlled with a minimal time offset and thus create the illusion of stereo sound. For the StereoSID, a mixed configuration with a 6581 and an 8580 is recommended in order to amplify this effect through the different sound of the two versions.

There are several conversions of Commodore computers to complete music devices, sometimes with more than one chip.

In the late 1990s, Scandinavian students, now known as Elektron Music Machines , developed the SIDstation , a professional MIDI synthesizer for musicians that works with a SID chip as a sound generator. The device was manufactured in small series and marketed commercially. After that, however, the chips that were no longer manufactured were no longer available on the world market.

If you don't want to do without hardware-based SID synthesizers, you can build your own SID synthesizer with the MIDIbox SID V2 .

SID chip replacement

Since the chip has not been manufactured for decades, resourceful hobbyists have built hardware-based emulators of the SID:

One approach is an Atmel AVR , called SwinSID . In the nano version this is no bigger than a normal SID housing and can be used instead. Since the original chip is only emulated, a very clear difference in quality is audible. The difference in sound is comparable to that of a transistor amplifier versus a tube amplifier .

Another approach is to emulate the SID in an FPGA (programmable hardware). This can also be used directly as a replacement.

SID software emulation

For all of today's desktop operating systems there are emulators in software that can play back the original compositions of the C64 from back then. In order to be able to play this music on today's computers, the SID file format was created . Players for this format are available for practically all platforms ( Win 95, Win 3.1 , Linux , MS-DOS , Mac OS Classic , AmigaOS , Atari Falcon , BeOS , OS / 2 , Android etc.). These are usually an emulator of the processor and the sound chip of the C64. Due to the semi-analog structure of the SID, an exact emulation of the sound image has not yet been achieved. An exact emulation is extremely difficult because of the partially analog structure of the SID, especially when the filter comes into play.

As VST software there is e.g. B. QuadraSID from reFX, a virtual synthesizer that emulates four SIDs in a MIDI environment via software, as well as the SID chip emulator Ton- Gerät 1 and the inSIDious from Impact Soundworks.

There are also web applications as online SID, microcontrollers and VHDL software for FPGAs.

Hardware synthesizer with SID emulation

In addition to pure emulation in PC software, some manufacturers now even offer devices and modules that simulate a SID and its sound in hardware, etc. a. the Therapkid and the SID box from Modemachines. There are also handicraft projects with DIY hardware with mixed analog and digital technology.

popularity

• Due to the great popularity of the C64, many compositions were created for the SID, which are now classics of computer music .
• The best-known programs with which music was composed on the C64 were called: JCH Music Editor , Demo Music Creator (DMC) , Future Composer or Sound Monitor .
• Even today there are artists who take a large part of their sounds from the SID. A good example of this is the minimal electro band Welle: Erdball .
• Under the terms "Micromusic" or " Chiptune " a very active scene has formed around the music of the old sound chips such as the SID of the C64. For example, the High Voltage SID Collection , a collection of over 30,000 pieces of music from the SID chip, and the Micromusic.net community, in which several thousand musicians exchange ideas, came into being.

See also

• Chiptune
• Sound monitor
• HardSID
• SIDstation
• MIDIbox SID V2

literature

• Brian Bagnall: People's Computer - Rise and Fall of the Computer Pioneer Commodore . Ed .: Winnie Forster, Boris Kretzinger. Gameplan, Utting am Ammersee 2011, ISBN 978-3-00-023848-2 (American English: On the Edge: the Spectacular Rise and Fall of Commodore . Translated by Winnie Forster, Boris Kretzinger).

Web links

Commons : MOS Technology SID  - collection of images, videos and audio files

• C64 - WIKI
• SID in-depth information site, dedicated to 6581, 8580 and 6582 - Comprehensive information on SID
• C64 SID chip programming - programming of the SID chip
• The High Voltage SID Collection - The SID Music Conservation Project
• Interview with SID developer Bob Yannes 1996 ( Memento from February 22, 2007 in the Internet Archive ) - with in-depth explanations of the SID design
• Slayradio - international web radio, which only plays SID remixes and originals
• Radio PARALAX - German-language web radio for SID remixes and originals
• Best VST plugins Commodore 64 Sound

Individual evidence

1. ^ Chip Hall of Fame - IEEE Spectrum. Accessed July 22, 2019 . 
2. ↑ ^{a b} Markt & Technik Verlag: 64'er 1993-09 . September 1993 ( archive.org [accessed July 30, 2020]).
3. ↑ 6581 SOUND INTERFACE DEVICE (SID). In: archive.6502.org. Commodore - Mos Technology - NMOS, October 1982, accessed in 2020 . 
4. ↑ SID - C64-Wiki. Accessed July 30, 2020 . 
5. ↑ Stereo SID. C64-Wiki, accessed July 2020 . 
6. ↑ JAHTARI - Dual SID Synthesizer. In: jahtari.org. Jahtari Leipzig, 2003, accessed July 2020 (English). 
7. ↑ SwinSID - Hardware replacement for SID 6581 8580 chip. Swinkels / Poland, 2012, accessed in 2020 . 
8. ↑ The FPGASID Project. 2018, accessed July 28, 2020 . 
9. ↑ Free of charge: Ton-Geraet 1 - a C64 SID chip emulator for the Windows world. June 3, 2020, accessed July 28, 2020 . 
10. ↑ Dirk B .: Impact Soundworks officially releases SID emulation inSIDious! In: gearnews.de. July 16, 2020, accessed July 2020 . 
11. ↑ Igor Zinken: Commodore 64 Synthesizer by Igor Zinken | Experiments with Google. 2018, accessed July 2020 . 
12. ↑ Markus Gritsch: Hybrid SID Player. Dangerous Prototypes, April 17, 2011, accessed July 2020 . 
13. ↑ Juergen Schuhmacher: Emulation of the MOSTEC 8051 SID sound with FPGAs. In: 96khz.org. 2006, accessed July 2020 . 
14. ↑ Test: Twisted Electrons Therapkid SID Synthesizer. In: AMAZONA.de. September 18, 2019, accessed July 28, 2020 . 
15. ↑ Mode Machines SID - a C-64 synthesizer emulation. In: AMAZONA.de. November 23, 2013, accessed July 28, 2020 . 
16. ↑ Kevin Horton's: FPGA SID. In: kevtris.org. KHV, 2011, accessed July 2020 (American English). 
17. ↑ Alex: C64SID - Commodore 64 SID Player. Papillo, 2013, accessed July 2020 .