MixSID Dual SID Board

While me and couple of hundred other SID fanatics are waiting for the SIDFX units to arrive, a new advanced dual SID board design appeared out of the blue; MixSID by Henning Bekel.

The arrival of MixSID is quite interesting, as feature-wise MixSID appears to be on-par with the SIDFX. Want to install any two SID models to any C64 model? Be able to switch between the installed SIDs on the fly? Choose between mono, dual-mono or true stereo operating modes? Have flexible selection for the second SID address space? Adjustable digi-boost for 8580? Volume level balancing for the installed chips? Reduced noise?

Check.

Both SIDFX and MixSID are capable with the above, and more. Of course SIDFX has even more some interesting features, including software configuration for the settings, and automatic configuration (voltage, filters) for the installed chips etc.

Comparing the two is not exactly the point of this article, but I can’t help myself doing that spec-wise, as both are advanced dual SID boards, with many similar features, and appearing around the same time.

The biggest difference between the two is actually the approach and design philosophy; SIDFX states being a plug and play, solder free solution that automatically detects the installed SID chips and configures itself accordingly. MixSID, in turn, is manually configured, comprehensively documented, open source, and DIY-friendly.

In fact, you can only have MixSID by building one yourself. You can go ahead and order or make your own pcbs, but Henning also sells the MixSID boards as kits, and I was sure to get myself one.

SwinSID Ultimate

I’ve written about the need and importance of having a proper replacement for the SID sound chip few times before. So I won’t repeat myself on that, as this is going to be a lengthy article anyway.

Because what we have here is big news on this front.

A duo from Hungary, Máté “CodeKiller” Sebők and Mihály “Hermit” Horváth have been working on improving SwinSID, originally developed by Swinkels.

What they have come up with is a highly modified and expanded version of the Nano SwinSID, now called SwinSID Ultimate. The enhanced hardware is mostly developed by CodeKiller, and Hermit has rewritten a new sound engine almost from scratch. The aim has been to make a more compatible, more capable SID replacement than what the Nano SwinSID already was.

At least the list of improvements is impressive:

SwinSID Evolution

Since it’s initial release in 2010, the Micro SwinSID from Swinkels has gone through some improvements over the years. These improvements have come in form of both hardware and firmware updates.

Most obvious improvement was the change of form factor from the Micro SwinSID to the more familiar Nano SwinSID. Initially the Micro SwinSID was based on DIL-packaged ATmega processor making the board that housed also a full-size crystal oscillator and couple of trough-hole components almost twice as wide as the SID socket. Some time later a redesign appeared that was based on surface mount components, squeezing all the same components into a small PCB that’s no larger than a real SID chip. Or at least as long as only area is considered. Pin headers, components and jumpers make the board somewhat thicker.

Micro SwinSID and Nano SwinSID side by side. Both designs have the same components and features, except for the additional filter jumper in Nano.

During the first few years since the introduction, there was couple of official firmware updates. These firmware updates improved the sound emulation and compatibility with the behavior of a real SID chip, reducing the number of cases where Nano SwinSID would not sound or act ‘right’. Down the line there was also a feature update that made it possible to select the filter emulation between 8580 or 6581-like behavior using a jumper.

These refinements have improved Nano SwinSID, making it more feasible SID replacement with each improvement. Sadly there hasn’t been a new official, or publicly available firmware for the Nano SwinSID since 2012. As if SwinSID had reached its maximum potential with some of its flaws to remain.

This changed in 2014 when Máté ‘CodeKiller’ Sebők stepped up with a new firmware.

Commodore 128 motherboard in high resolution

Here’s a high-resolution photo of C128 motherboard for no particular reason:

Click for more pixels

This one has a Scandinavian character set, that’s why the three paper labeled EPROM chips.

One point worthy of note, though; You often find being said that the Commodore 128 has the “new SID”, 8580. That’s not the case however.

SwinSID analog controller hack

I’ve covered SwinSID micro and nano few times before. It’s a great idea – a micro controller based SID chip replacement, working as a spare part  for a C64 or C128, or as a substitute to some other application like a DIY-synth. For Commodores, it’s especially suited for a gaming machine, as only very few games feature such tricks that would not sound about right on the SwinSID.

However, there’s this downside with the SwinSID that it does not support analog controllers. This is because it’s the SID chip that handles the reading of analog controllers in the C64, and the A/D converters are not implemented in the SwinSID. The number of games supporting paddles, mice or analog joysticks is not that big, but still it’s a shame that they won’t work with SwinSID. Also the few games that support second joystick button are affected. They behave as if the second button would be triggered constantly.

So there is a lack of fully featured replacement for a SID chip. This is a shame as SID chips are sought after, and supply for good and working chips is getting more and more scarce. The demand of SID chips have been recognized, as it’s not that difficult to find a supply of SID chips from Asia. It’s just that many have found out that these chips are often dead, faulty or downright fakes, and often rebadged.

Knowing that there are a lot of these faulty SID chips with bad filters or missing sound channels, it had occurred to me that maybe these could be combined together with SwinSID to make at least a fully featured replacement for the SID chip. Sound from the SwinSID, and A/D converters from an otherwise faulty SID.

Recently I ordered some spare parts from Mutant Caterpillar Games, who have a selection of chips for 8-bit computers in stock, including SID chips. As we were talking together with Ian Gledhill about SID sourcing challenges among other things I mentioned this idea of mine. He kindly sent me few faulty rebadged SID chips to test it out.

So, off I am to build an adapter that allows me to install SwinSID and a ‘badSID’ to the C64.

Stereo to C64 with DualSID

I finally assembled one of my DualSID kits. It’s an add-on board for C64 that makes it possible to install an additional SID chip with several different configurations. Detailed description can be found at the DualSID home page or in my earlier post.

Update in April 2018: The DualSID home page is gone, so I add the latest(?) versions of the assembly instructions here, plus link to Lemon64 forums.

• dualsid_assembling_instructions_6581_v3
• dualsid_assembling_instructions_8580_v3
• Discussion, mods and fixes on Lemon64 thread

Note: the transistor orientation is incorrect in the pcb silk screen in pcbs prior to pcb v3. However, letters E, B, C are printed correctly on the board, so check your transistor pinout. Pictures seen on this post have the transistor installed wrong way around. Transistor’s flat edge should face towards edge of the board. I’ve fixed mine since. </update>

I made this one as the 8580 version. Here’s the board – without and with SID chips.

For the convinience of installing it from one C64 to another if needed, I made all external connections and jumper settings using pin headers. When the board is like this, the second SID address selection is done by setting the jumper block in the 2×4 pin header to correct position. Instead of manually changing the jumper block’s position, I’m able to replace the block with 2×4 female pin header that is wired to e.g. a rotary swithch. That way the changing of second SID address can be done externally.

While I’m unboxing my own stuff…

It feels like it’s been ages since my last post. One reason for this feeling is probably the fact that I have moved during this break. Being more specific, I have moved in with my special lady. Who does her best to understand my interest to old computers and other weird stuff including my peculiar electro-analogish taste of music. Wish me luck ;)

Not starting a relationship blog here and still sticking to old computers and weird stuff; Some interesting SID related updates have emerged in the meantime for both SwinSID and 1541 Ultimate projects.

Micro SwinSID has got two firmware updates since my review. The updates have improved the ADSR envelope and filter emulation closer to real SID chip. The latest firmware also introduces 6581 filter emulation that can be selected by e.g. a switch by grounding one of the AVR pins. Unfortunately I haven’t had the change to get first hand impressions of the improvements as I’m lacking the means to program the microcontroller.

New DualSID boards

SID-goodness just keeps on coming. Some while ago Tomi Malinen released his DualSID twin-SID PCB. Depending on how the board is assembled and configured you can add either SID model to any C64 model. Additionally, the second SID address can be configured using jumpers. With DualSID board you can have both SID models in one C64 or configure yourself a stereo SID setup for any twin SID application. Anything goes. It’s probably the best and most versatile PCB design so far for adding another SID chip into C64.

I ordered myself few kits already a good while ago, but I have been lazy with my C64 activities lately and have not yet assembled them. I will have to come back to this topic once I have assembled and installed one.

Meanwhile if you’re interested for such board get familiar with the DualSID web site.

Here’s a picture of the kits I ordered:

Three DualSID boards and components for one 6581 and one 8580 model. While the board is the same there are different ways to assemble it depending on which SID model you are going to have as the second one. The FAQ on the site will help to understand the possibilities, limitations and why there are two different ways to assemble the boards.

Also, HVSC update 54 is out!

Micro SwinSID – an AVR based SID replacement

SIDs are sought after sound chips. Being semi-analog they are difficult to emulate. They also break easily from e.g. static discharges. If one is to build a SID synth or you need to replace broken SID chip you may have trouble finding the chips.

SwinSID is a project that I have been keeping an eye on for many years now. Swinkels, the man behind the project, has been prototyping and developing a SID compatible custom sound card for C64 or other SID-utilizing devices such as MIDIbox SID.

Originally the SwinSID was not aiming to emulate a real SID chip but rather to be a pin-compatible SID-like sound device with some enhancements. The hardware is based on one or two (stereo) Atmel AVR microcontollers and some additional circuitry including a DAC.

But now Swinkels and Crisp have developed a new model of a different goal. It is called SwinSID88, or Micro SwinSID, and it’s a direct replacement for the SID chip. It is mono only and it aims to emulate the sound of 8580 SID chip as good as possible.

ACID 64 Player Pro supports SID emulation!

This should be interesting to majority of SID music lovers. Starting from v3.0.4 ACID 64 Player Pro supports JSIDPlay2. Up to this point ACID 64 Player Pro has been a SID player software only for HardSID users as it has been supporting only HardSID for output device. But it’s now possible to configure JSidDevice as the output source!

What this means is that SID sound lovers who don’t have a genuine SID sound card setup can now enjoy today’s state of the art SID emulation with the wonderful ACID 64 Player.