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Other Platform SID Extension Cards
by Taper/Triad


The revolutionary design and next to divine sound of the SID chip is certainly unique. No wonder then that it became the envy of owners of other computer systems back in the 80's - and apparently still today!

No denying there has been some amazing music produced with other famous sound chips as well. For example the well-known AY-3-8912, used in computers such as the Spectrum 128K, MSX and Amstrad CPC, or the RP2A03/RP2A07 which we find in the NES/Famicom. Even the beeper in the Spectrum 48K has been forced to perform some insanely good tunes, but it's not only we in the C64 community who seem to prefer the sound of the SID when choice is free.

So, what is a poor owner of a [insert other classic 8-bit computer here] gonna do about it? Well, getting a SID-interface card would seem like the sane thing to do... Thus, this article will try to cover the existing SID-interface cards for classic computer systems. That also means that I will not dig into the various PC interfaces such as hardSID, parallel port SID or stand-alone units such as the SIDStation. Nor will we discuss the SIDPlayer for Raspberry Pi.

Note that we in no way endorse people to butcher Commodore 64's just to get their dirty hands all over the precious SID! Some people have been known to practice such sacrilege offences, in which cases we endorse fierce punishment instead. However, for those who own both a C64 setup and another 8-bit computer, sharing is caring!

Do remember that the SID is sensitive to static discharges though, so swap with care and use proper protection (yes, that did sound like a carbon copy of the rules for your local swingers club).

SID interface cards are not new inventions. For some systems they have been in existence since at least the early 90s. A few individuals completed their personal projects around the SID-chip even prior to that, like Mogwai/Censor Design who created his own personal Walkman containing a SID-chip way back.

Now, let us see what interface cards we can find for various systems and learn a bit about their different approaches. Some cards are mainly designed to be able to play C64 tunes, while others are using the SID chip as a "generic" sound card for the specified platform.

Commodore 16 and Plus/4

Perhaps the most well-known SID-interface cards available are for the younger cousins of the C64, the C16 and Plus/4. A whole bunch of different cards exists for these machines, and quite some software support is available as well. Most cards are old designs though, and can't be easily obtained today, unless you find them second-hand of course.

One modern card still on sale, and also the current Rolls Royce of C16/+4 SID-cards is the NST Audio Extension V2.0. Obviously equipped with a standard audio out jack, this card also contains a DSUB9 for one extra C64 compatible joystick (or an Amiga/Atari ST mouse), as well as the possibility to mix SID and TED audio output on the fly! This card is highly praised by owners, but only supports the 8580 SID out of the box. It is possible to modify the card for use with a 6581 chip, or you can make a special order for a 6581 compatible version, in which case the price might be higher and delivery time longer.

There is also a much more rare SID-interface card available, made to be installed internally in your C16/+4. This one is called TEDSID, consists of a daughterboard mounted in place of the TED, and then the SID and TED are moved onto sockets on the daughterboard instead.

So, what about the software support then? Well, you can find anything from TED games and demos to trackers (like Future Composer) compatible with the cards. All in all, plus4world.powweb.com lists 250 productions supporting SID-cards - the most recent release being Genesis*Projects MerryXmas from 2015 (which also was released on the C64 by the way).

VIC 20

Sound and graphics on the VIC 20 are handled by the VIC-I chip, which naturally is quite a bit less advanced than the SID and VIC-II. As strange as it might seem, the VIC 20 has never been graced by a commercial SID-interface product. I know of at least two hobbyist projects that were successfully completed though, one cartridge based and one that seem to be an internal hack. A Battleship game supports the latter project, but information is scarce and software support even more so. Worth mentioning is the SID Vicious converter/emulator which lets the VIC 20 play SID tunes in quite a decent way, but that solution is not hardware based, and thus uses up most of the resources of the computer so it is hard to do much else of use while playing a tune.

BBC Micro

The BBC Micro was most commonly found in the UK and other commonwealth countries where it could be seen in schools as well as in homes. It was also used in some quantities in US schools. The most common SID card for this machine is the BeebSID interface, built by Martin Barr.

It hooks up to the BBC 1Mhz bus and needs an external 9 volt power supply to function. It's basically a little external box containing the card and audio output jacks, which then connects to the BBC bus using a ribbon cable and draws 5V and 12V from the BBC aux port. BeepSID is made for the 8580 SID, although it can of course be modified to work with a 6581. Software support is sadly lacking a bit, but a some music collections with C64 tunes as well as a few demos and games exists which can utilize the card.

Texas Instruments TI99/4 and TI99/4A

The Texas Instruments TI99/4 was the first home computer sporting a 16-bit CPU, the TMS9900, also manufactured by TI. Model 4A followed soon thereafter, which is basically the same computer but with a new keyboard and support for bitmap mode in the updated video chip. However, the powerful CPU is severely hampered by a clunky design as only 256 bytes of memory is directly accessible for the CPU. The rest of the 16KB on board is graphics memory, and the CPU has to go through the video chip to access additional RAM. Sound-wise it contains a 3-voice SN94624 sound chip (also known as SN76489) from TI.

Texas Instruments were decisively beaten by Commodore in the home computer wars of the early 80's, and the TI99/4A was discontinued in early 1984 after selling a still respectable 2.8 million units. That didn't stop enthusiasts to continue to support the machine though, and thus there is at least one SID interface card available for the 99/4A. The card is named SID Master 99, and in addition to your 99/4A computer you also need a PEB (Peripheral Expansion Box) to use it. The PEB has 8 slots for expansion cards, but one of the slots are always used to interface the unit with the computer, so you can have up to 7 cards in this external box. The SID Master 99 can be accessed using assembly, extended basic or any other language that allows normal CPU memory access.

No external audio jacks are needed which is quite nifty, the card is fully compatible with built-in 99/4A sound chip, and SID sound plays through monitor or TV just like internal sound chip does. The card comes with a SID-player that can play files from the Compute! Gazette SID Collection, but that does not mean you can throw an ordinary HVSC SID-file at it. The 6510 is by no means emulated here.

MSX

Yet another Commodore competitor from the past was the MSX line of computers, mostly popular in Japan but with a decent user-base also in Holland, Eastern Europe and the Arab world. MSX was a standard and several manufacturers produced machines complying with this standard, including Philips and Goldstar (nowadays known as LG). Naturally we can find a SID card for the MSX machines as well! The Playsoniq multi expander card from Supersoniq is actually shipped with a SID-chip (let us hope they don't molest C64's in the sales process - that would mean I have to put fire to my boxed mint condition Goldstar MSX as a revenge).

Now, the Playsoniq is a weird beast which could best be described as the Frankenstein monster of expansion cards. It contains a Sega 315-5246 Audio/Video chip, the same chip that sits inside a Sega Mastersystem II (the Sega Mark III and early Master System consoles use the 315-124 chip instead, which is basically the same chip but with some bugs). It's quite a capable graphics chip for its time, supporting several resolutions, up to 32 simultaneous colours and 64 sprites on screen at once (8 per scanline) as well as being compatible with MSX-1 video-modes. The built-in sound generator is compatible with the Texas Instruments SN76489(A), used in many home computers and consoles such as the ColecoVision. The card is also equipped with 16 megabyte of extra memory.

As you might already have guessed, the Playsoniq can actually play Sega Master System (and it's cousins Sega SG-1000 / SC-3000 / MARK III) games on your MSX. In addition to this, the card also supports either a 6581 or an 8580 SID on board. MSX-1 computers run on Z80 CPU's, most clocking in at 3,58 Mhz. As the SID needs a clock speed of around 1MHz, buffers had to be implemented so that writing to the SID would not result in stuttering sound. Both PAL and NTSC Commodore clock speeds are supported.

Amstrad CPC

Moving on to the Amstrad CPC, another Z80 driven home computer, usually running at 4Mhz. The CPC uses the General Instrument AY-3-8912 sound chip. Currently there seem to be two different projects aiming at offering SID expansion boards for Amstrads classic computer, Bryce CPC-SID and the Sonique Sound Board. The latter is planned to be delivered with a SwinSID because of the scarcity of real SID chips. None of the projects have yet been completed and offered for sale, though.

Sinclair Spectrum

There seem to be no completed SID card project for the arch nemesis of the C64, the Sinclair Spectrum 48K. There is a card in development however, entitled the SID-Blaster/ZX. To be able to play C64 tunes, the card also boasts a 6510 CPU. Information is scarce, but examining a picture of the prototype reveals several MOS chips on the board. The board is quite large and it almost looks they are trying to interface a full c64 with the Spectrum, which seems a bit pointless. Time will tell if this project is completed. I personally hope it won't be - they'll likely have to butcher a whole lot of c64's to produce these cards.

SAM Coupe

The SAM Coupe is a rare British home computer released in 1989 as some sort of a unofficial sequel to the Sinclair Spectrum, initially manufactured by MGT. The SAM runs on a 6Mhz Z80B CPU, but is still only about 14% faster than a Spectrum 48K, mostly due to memory contention delay when RAM is shared between CPU and the graphics chip. There was little place for yet another 8-bit computer in 1989, as other platforms already had large user-bases and 16-bit machines were becoming more popular. About 12,000 SAM Coupes were sold before it was discontinued in 1992.

However, the machine has a small cult following of its own, and thus there is a SID card available for it, entitled SID Soundchip Interface. Developed by Quazar (a company dedicated to serving the SAM community with software and hardware) back in 2003 and with an updated version released in 2014, this card is still on sale. What makes this card quite unique is the fact that it is bundled with a SID playback emulator from Simon Owen, which actually uses software emulation to run 6510 machine code. This makes it possible to run .sid music files in realtime.

Amiga

Moving up to the 16-bit generation of machines, also the Amiga has some cards supporting SID-chips. The most common is the Catweasel PCI or Zorro II disk drive controller card, which main function is to provide a way for diskdrives of many different sorts to be interfaced and accessed. This card also boasts two DSUB9 connectors for extra joysticks, and a socket for the SID-chip. Note that this card can also be used for PC's running Windows as well as Mac computers.

IBM PC and compatibles

There have been numerous SID-interface cards for the PC, and as promised I will not dig through them in this article. But, three cards do deserve a special mention.

Microprose developed their own soundcard for the IBM PC back in 1987 as they started to grow tired of using the internal PC speaker for their games. Being used to far superior sound hardware on the C64, Atari ST and Amiga but noticing the increased interest in MS-DOS games (especially in the USA), Microprose decided to solve the problem. The product was named The Entertainer and contained a MOS 6581 and one joystick port. Two games are known to support the card, Gun Ship and Sid Meier's Pirates! - however the card is so rare it's uncertain if it was ever shipped to customers. If it was, the quantities must have been very low.

The Innovation SSI 2001 ISA sound card plugged into any IBM compatible PC, including PC, XT, AT, 386 and PS2 - and featured a 6581 (some sources say 6582) SID chip on-board. It aimed to be a cheap competitor to the more expensive Adlib soundcards and was most likely released in 1988. Despite the price point and Innovation offering software houses a simple system to convert music or sound effects from the C64 to MS-DOS based machines, only a little more than a dozen games ended up supporting the card. The known compatibility list includes Airball, Bad Blood, Battle Chess II, BattleTech: The Crescent Hawks Revenge, F-19 Stealth Fighter, Falcon A.T., Harpoon, Joe Montana Football, Lord of the Rings Volume 1, Red Storm Rising, Super Jeopardy, Ultima VI and Windwalker.

According to the creator of the SID-chip, Bob Yannes, the synthesizer company Sequential Circuits were once interested in buying SID-chips from MOS Technology, but in the end no deal was made. Back in the 80's MOS Technology was a merchant semiconductor company and did sell chips to the outside world. However, with the success of the Commodore 64 there was little interest from Commodore (or production capacity for that matter) to push specialized chips such as the SID to the open market. The Innovation 2001 sound card is thus one of the very few products known to have been shipped in at least some quantities and which contained a chip otherwise thought of as exclusive for the Commodore 8-bit line of computers. This makes Innovation 2001 a truly unique card.

The last soundcard for PC I will mention here is even more rare than the one from Innovation. It is named the Mating Sound Simulator, equipped with a 6581R3 SID and manufactured in 1988. This is not your ordinary run of the mill soundcard, this card was produced only to simulate fruit fly courtship songs! Only one such card is known to still exist, and markings on the PCB indicates that it was most likely developed at the Department of Electrical Engineering in the University of Oulu, Finland. The remaining card was found in the biology department recycle bin at the same university in early 2016!

This card was covered in an article in the scientific magazine Drosophila Information Service, so it's safe to say that several were made, but the production run was likely very small due to the limited audience for such a unit. How the chips for this card were obtained is uncertain, perhaps they simply bought a stock of spare-part SID chips from some repair shop.

Conclusion

As C64 sceners we all know how precious the gold embedded under the hoods of our Commodore 64's is, and how it has graced our ears for so many years. It is obvious that the love for the unique sound of the SID is not confined to our realm of the scene. With the new improved SwinSID Ultimate on its way, those wanting to enjoy the sound of the SID on other platforms using an extension card will be able to do so without butchering C64's in the process. That is without doubt good news - the future of the SID is bright!


Do you know of any SID interface cards for computer platforms not mentioned here? Give us a shout, we would love to hear about it!

TAPER/TRIAD

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