Finally! No mouser package, but I was able to find all the needed ceramic caps in my junk boxes, and the last missing item, the sliding switch, arrived today from China, so my all-socketed C64 is finally up and running with a new RF modulator replacement. I'll have to submit to the same treatment one of my shortboards next year.
As soon as they're available again, I'll also buy a lumacode encoder for this C64, and will probably go for a sidkick pico too. The SID in here doesn't sound terribly good.
I also built a few KungFu Flash carts, so it's time to play around a bit... Any pointers to nice C64 games on itch.io, people?
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Also, why not replacing the DRAM with SRAM?
I used this for the carrier: https://github.com/go4retro/DRAMCarrier (there is an error on this board: pin 1, which is /OE, of one of the ICs is left floating, I had to jumper it to GND, like it is in a C64C) and https://github.com/jamarju/c64-sram (here the BOM lists an HCT32 to handle /RAS and /CAS but I had timing issues with that, the issues went away with an F32).
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Further work on the experimental C64, to attempt lowering the temperature inside the case: removal of VR2 and replacement with a switching module from Murata (I have an abundance of these). I also added some additional filtering with ceramic caps on the bottom, and, while I was there, replaced the 10uF caps across the board with newer, higher rated ones.
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Oh I ran into a small issue with the SRAM replacement board from the previous post!
See those two tiny pixels under the cloud? At the main screen of ZetaWing II there is a segment of flickering pixels just under that cloud. The issue disappears when using the original 4164, or even when replacing them with two 4464, so I'll go with the second option.
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I'm planning to get a few sidkick picos built by PCBWay, but while rummaging around looking for ICs to test I found an armsid I ordered as a spare in a lot that I got to fix up a friend's C64, so I decided to pull the original from this machine, store it away safely and install/update/test this one.
It's really, really good, at least to my untrained ears. Might just use the skpicos on other machines and leave this one in here.
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@hkz very interesting. I am working on a MIDI synthesiser with two SwinSID’s. They work fine, but I hear a lot of aliasing on filters. Most comparison videos I’ve seen test the different SID replacements only with complete tunes (that I don’t know). It would be easier to compare them using simpler sounds showcasing problems (aliasing, etc…)
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@davbucci @hkz SWINSIDs are pretty bad in regard to filters. ARMSID is in my opinion currently the best bang for the buck if you want to go replacement SID. Costs about 35€ and has very very good emulation, including filters.
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@root42 @hkz the SwinSID filters are abysmal 😩. As a comparison, here is the output of a real C128D, with a SID 8580. It's low (as in the emulator) and quite noisy, but no aliasing can be heard (as expected, as filters are analog, there). The SwinSID in the previous example is configured as a 6581, though. I will try in the 8580 mode, too.
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@davbucci @hkz I think the tiny MCU on the SwinSID is just too weak for this. The ARMSID has an STM32, which is much more powerful. I guess filters will be implemented as FFTs, so weaker MCU will have less bands and hence aliasing… I guess?
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@root42 @hkz I thin they are FIR filters, easier to calculate than a FFT. However, it's certainly true that with a better micro the results can be much better. I was just not expecting such as high level of aliasing with the SwinSID. On the other hand, I'm playing with the C128 right now and the real SID is far from perfect, but at least there is no aliasing! 😊
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@davbucci No SID is perfect. Which is why we love the SID so much. :) I think it is really THE sound of 80s micros. Amazing what it can do, and the variety of sounds you even get from one SID to the next.
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@root42 an amazing little device, indeed. I would like to obtain a fun synth to use and I think it is clear now that I have to upgrade from the SwinSID.
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