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Comment by Jaruzel | Hacker News Reader

Because the SID deals with analog as well as digital signals, it's not that easy to clone, however you can get fpga versions such as the SwinSID - https://www.c64-wiki.com/wiki/SwinSID

Unfortunately, the SwinSID (and similar) do not sound anything like the original chips when playing music.

Consequently SID chips are quite expensive to buy (relative to what they are) - any effort to accurately clone a SID chip would be welcomed, as it will drive the cost down of these chips on ebay etc.

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Sorry to be picking a nit here but the SwinSID is not FPGA based, it's a software emulator running on an AVR mcu.

There is an FPGA based version of the SID called (surprise) FGPASID (http://www.fpgasid.de/) which is pretty much indistinguishable from an original SID. The only real downside to it is the cost, it's not a cheap one.

The FPGASID was created by decapping and reverse engineering original SID chips and the result is pretty spectacular.

>it's not a cheap one

80€. You're right, it's not cheap, but I actually expected much worse.

And, it emulates two SID chips and has multiple modes (6581 and 8580), so it seems like a pretty darned good deal, honestly.

Real SIDs are pretty pricey these days, and they aren't making any more of them, so they will keep climbing in price for as long as people find them interesting. So, it's good to have an alternative.

Wow, didn't know normal SID chips went for about $40,- nowadays.

> Sorry to be picking a nit here but the SwinSID is not FPGA based, it's a software emulator running on an AVR mcu.

I sit corrected :)

There are other, newer alternatives, and they are getting difficult to distinguish from a real SID, especially given no two SIDs sound the same - e.g. http://dzi.n.cz/8bit/arm2sid/index_en.php

Original SID chips are often semi-broken as well. I had a few when they were cheaper and I was building a midibox SID. Most had weird VCA issues or oscillators leaking to the output always. Stuff like that. If you end up with a half decent one the oddities just become part of the charm.

There were two variants of the SID. The early one ran on 12v and the latter on 5v. As I understand it, the reduction in voltage greatly improved their reliability.

More than just the voltage, the 8581 had significantly revised circuitry and better opamps due because they had much more silicon area and a better process available.

It sounds disnctively different too.

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