J-CIA64 – Modern spare part for Commodore 64, Commodore 128, SX-64
1nt3r.net
1nt3r.net
I've given up on owning a real C64, just to remind me of my childhood. It's too convoluted, requires buying replacement parts, and I don't own any TV to plug it into. VICE emulation is good enough for me. But I really wanted the keyboard, which was a major part of the experience for me.
Out of the box -- no soldering, not buying extra cables or expansions or add-ons -- the most feasible option for me was buying the retroremake TheC64 ("max", the full version with the working keyboard).
Is it perfect? No.
Is it a C64? No. It looks like one, but inside there's an ARM chip running VICE.
Does it look like a convincing C64 "breadbin", and can I play every game, type BASIC programs, play with PETSCII art, even type assembly code, and generally relive my childhood?
YES!
Yes, I know: you can get custom keyboards, or print labels and stick them on a PC keyboard, or 3D print a case with a working keyboard: all of that is either more involved, more expensive, or fiddlier than what I wanted.
I wanted an out of the box experience with a working replica of the keyboard, complete with PETSCII symbols on the key caps, and TheC64 delivers just that :)
What I find great is that you can plug in a USB stick with all the C64 games ever made and just load them quickly up using the Ultimate 64 built-in software.
I have both "real" C64s and the Ultimate 64, but I only use the Ultimate these days. It's just easier.
And even when it might be available, you can get two or three real C-64s from eBay for the same price.
For me, working on a real 64 is essential but I don't care about disk drives at all. So a Commodore 64 + Ultimate II+ (or pi1541) is a great combination. I love being able to use real 64 joysticks with no lag.
Keeping the hardware going is half the fun - I have replacement chips for everything on the board, diagnostic carts and have enjoyed picking up soldering again.
For Assembly language programming though, Visual Studio Code + Kick Assembler + Vice + C64 Debugger all the way!! Makes the development and debugging process completely seamless.
Modern hardware can emulate an 11 much faster than any real one ever built. RSTS/E installs in seconds when your "disk" is NVMe and you don't have to wait for a DECwriter II console at 30 cps.
I can understand that... I'm lucky in that my very own C128, after nearly 40 years, still works. I think the C128 is a bit easier to get going because the PSU are of much better quality than the C64's PSUs and IIUC the C128's PSU is less likely to destroy the computer should it malfunction.
I wrote it recently in another thread here on HN: I've got both original PCBs from the eighties and a Raspberry Pi in a vintage arcade cab and it's pretty much giving identical results (except for the boot procedure).
Emulation may not be the real thing but it really became close enough.
We have options and we should be happy about it.
And as my electronic and soldering skills are really mediocre, I fear the day where my C128 shall eventually give up.
And this basically goes for all the old nostalgic hardware I've got. For kicks I booted up an old Sun 3/80 I picked up a bit ago. After replacing the failed hard drive with an SSD on an adapter board, figuring out how to regenerate the boot info on a replacement of the dead battery backed RAM chip, and getting it to actually net boot off a Linux host, I realized SunOS 4.1.1 is a lot more of a pain in the ass than I remembered from back in the day. It was an amusing adventure, but it did make me think twice about trying to boot up my old SGI Indigo.
Also, it’s a good introduction to understanding full systems, from the electronics—soldering, voltage, current, etc to assembly programming. The system is simple enough for them to ship circuit diagrams in the developer manual—along with all the opcodes and kernel routines.
There’s a resurgence across all fields in artisanal craftsmanship. Carpenters, blacksmiths, printmakers, cobblers.
Retro-Computing is exactly that—artisanal electronics and programming. There’s something meditative and enjoyable about it.
So the older machines are an important conceptual building block. And they're not academic exercises taught in theoretical simulation but never experienced, they're real physical machines that did useful things for people who are still around and can walk you through doing the same things on the very same machines.
The other magical thing about home computers of that era, was that they were ROM-based, with very explicit operations to commit data to nonvolatile storage. You couldn't accidentally delete a system file and render the machine unbootable, and that encouraged experimentation in a way that subsequent PCs harshly punished.
Also, while 8-bit home computers weren't really toys, they were _almost_ toys, in that very few folks were running a business on their C64. (And again, even if they did, all they had to do was lock the business disks in a cabinet at the end of the day.) So the consequences of even a major screwup were limited, again in a way that the next generation of PCs dramatiaclly reversed. I knew kids "grounded for life" (actually a few months) in the 90s because they hosed up the family PC that mom or dad was doing the taxes on or whatever. That simply wasn't a thing in the 80s.
All of learning is making mistakes. One hundred percent. And modern machines don't allow it in the same way. We were privileged to learn in a real-but-nearly-consequence-free environment, which today's kids will simply never experience.
I have a MIST, Vampire board, and still play around with UAE from time-to-time... but there's nothing like seeing the "real" hardware for the first time when you were a teenager. Even with all the hardware I've had over the past 30 years, everything else has felt so incremental.
Back then, very few people had these. Now, nearly everyone has something much much more powerful in their pocket/purse or on their wrist.
I do pity younger kids today not having that feeling. The was a mystique around them. Now, it's just part and parcel of everyday life. Everything new now is just an upgraded version of something prior. Back then, it was all so new. I can't think of anything that would have the same feeling for kids today.
I thought I'd try to turn it on but got spooked by the requirements for the PSU
I understand it needs ripple free 5VDC 2-4A+ through a 7 pin din
Am I really going to blow the unit up with a switch mode, does it really need linear regulation?
What's stopping me using 2-3 LM7805s in parallel?
[Background] former burnout frontend dev working at an electronics shop
I am no EE but I would be very surprised if they are linear.
I think ripple-free is by 1982 standards ;)
The PSU situation isn't great: building your own is difficult (see https://www.c64-wiki.com/wiki/Power_Supply), and using an old "real" PSU is risky, because they tend to produce >5V as they die, taking the C64 with them. That's why I ended up using the Ultimate 64 rather than a real C64: just supply it with 12V DC from basically anything, and it will be fine.
For younger folks, the SID is the sound chip of the C64. It's infamous for being partly an analog circuit. That is, it uses transistors in states between 0 and 1, as you would in a transistor-based amplifier, or an analog radio. This gave the sound of the C64 its unique texture.
My understanding is that this behavior is impossible to reproduce with modern chip fabrication techniques, so what's the solution? Digital emulation?
What's difficult is replicating it with generic programmable platforms like FPGAs because those are mostly digital gates.
But if we'd just want to cook a bunch of SID chips that's no problem. It'll just be hard to get enough interest to warrant all the design and setup work. You'd need to do a large batch to make it worth the investment.
That said, if I were to do music production, I'd use my real chip, because I prefer the sound of it.. But, on a PC, I'd use one of the libraries, like libsidplay which emulates the sound better than the ArmSID.
The same could be said for the VIC2 chip, I've yet to encounter two that give the same image, they look slightly different. There, I do prefer the look of the kawari on s-video, it's just.. easier to see ^_^
Might just be old age? At some point, IC's may be degraded to a point where few (if any) work exactly like original part when it was new. And thus also differ between specimens.
At some point, original parts may become unreliable / quirky / glitchy enough that picking some kind of re-implementation (rather than original) as the "gold standard" is the only way forward.
Not a big issue for 'pure' digital parts like CPUs, glue logic etc. But (partly) analog IC's like sound or video chips... different story.
Seen from the perspective of microcomputers, which mostly either used simple square waves, or FM synthesis to generate sounds, the SID is unusual. But seen from the perspective of sound synthesis the SID is an analogue subtractive synthesizer[0] which, at the time of its design, were commonplace. As I say, that was pretty unique amongst microcomputers, and is why the SID was and is revered by fans of the 8-bit era: it has a really fantastic, crunchy analogue sound, that other computers of the era just don't and, indeed, can't reproduce.
I'd go as far as to say that Commodore missed a massive opportunity with the Amiga in terms of use for music: if it had the PCM based Paula chip, plus a SID chip (or even two - a man can dream), it would have been absolutely incredible.
In recent years analogue synthesizers have experienced something of a resurgence although, in truth, they never completely went away. As such ICs with analogue circuitry are actually relatively commonplace. Now that doesn't mean you can just remanufacture the SID chip really easily, but it is absolutely possible to build ICs with analogue circuitry today: as a trivial example, analogue to digital converters are commonplace.
[0] I think strictly speaking it's also a paraphonic synth, since all the voices share a single filter, but I can't remember off the top of my head whether they also all share a single amp (again, a hallmark of a paraphonic, rather than a true polyphonic, synthesizer).
Emulating the distortion is done with varying levels of accuracy.
Additionally the fabrication varied from part to part and from rev to rev. So the sound of any SID is a combo of its batch of substrates limiting bandwidth and the intermodulation distortion (IMD) of its FETs' imperfect emulation linear adding and multiplication functions increasing the bandwidth. Note that these non-linearities are in a feedback loop.
Furthermore the external caps ("matched") used for the filter varied considerably, but this is more easily reproduceable.
The envelopes are unconventional too, but more easily emulated than the filter. They are a mix of linear and exponential and use the non-linear FET multiplier.
Also the oscillators are not simple analog oscillators. They're high frequency lookup tables with digital aliasing related to the key the music is written in. The noise waveform is not analog, either, but a variable frequency LFSR, although this is easy to reproduce in FPGA and somewhat in software, although the max frequency can be challenging.
Finally the entire signal chain is replete with IMD so any melody/rhythm played on one voice is affected and influenced by what is played on the other voices.
In summary the SID was designed by electronic musician Bob Yannes who modeled it after typical analog synths but was technically limited by the fabrication of the age to make it less clean than even the grungiest cold war soviet synth. Still it was better than everything else at the time and it got a lot of loving attention from devs and musicians who squeezed every ounce of juice from it.
IDK - the first DAWs were made for the Amiga. If the Amiga hadn't already died-out by the early-ish 90's then I'd imagine Pro Tools would have been created on that and there would be a very real possibility we'd still be using Amigas today.
In a world where the Amiga didn't need an external MIDI interface, I suspect things would have been different.
1. Built-in MIDI interface.
2. High-resolution screen available, 640x400, 60Hz monochrome.
3. Simplistic operating system, the DAW software had 100% control of all hardware and timings.
I was really into Koyaanisqatsi at the time and you'll definitely hear the influence there.
FPGASID - https://webstore.kryoflux.com/catalog/product_info.php?produ... reDIP SID - https://github.com/daglem/reDIP-SID
https://www.youtube.com/watch?v=Qhdc-jgwqVQ
Studying how the old chips work and recreating them is an excellent way to document and preserve. I'm always happy for projects like these. The eventual availability of Amiga CIAs will save some old hardware, too :)
>Installing the J-CIA64 requires delicate handling and taking the proper precautions to prevent antistatic discharges.
Also, at least in my non-expert opinion, in most cases you should consider installing a socket whenever replacing chips. You have to solder something new on anyways, may as well make it something that you won't have to redo any time soon. I wound up doing this for every chip I replaced in my own C64, which made debugging it a lot easier. (It was borked when I got it. I'm too young to have owned one new.)
In terms of space, it feels like there's plenty of room in mine. I have the Perifrantic VIC-II switcher setup as well, which sockets a daughterboard with 2 VIC-IIs into the socket, and that fits surprisingly well. Though, I'd not be surprised if some models had less room to work with.
The low-profiles I wanted for two reasons, aesthetics, I like how they look, comared to the traditional tall green/cyanish giant monstrocities, and practical: Some of my fake devices are tall, and I risk running out of room in the C64c case (also true for chips below the keyboard), but also, the traditional zif sockets have a much larger footprint than a standard dip socket, and so they actually don't fit on my C64, they collide with decoupling caps AND with each other in one axis (I think it was the PLA and SID that couldn't coexist).
So, I opted for the waaahy more expensive low-profile ones
My Ultimate 64 has a real SID in a socket :-)
This is unlike the recently released VIC-II Kawari[0]. That one is OSH proper.
"100% Amiga generated web content"
https://retro8bitshop.com/wp-content/uploads/2023/08/F2eV4mB...
But I get it, it’s really hard to accurately replace legacy components as time moves on, it probably will feel like one but as it’s not all original it will never meet an unattainable expectation.
Put another way: You can pull an 8520 from an Amiga and put it in a C64 and most users will never know the difference (been there, done that, horrified my parents who saw me involved in surgery on our two computers) because most C64 software never uses the clock function of the 6526. As long as it provides the IO functions you mostly rely on, most users will never know nor care about the difference.
> Replacing original parts with microcontrollers would take away a lot of that pleasure.
Why, when these parts react to the same electrical signals in the same way? In this case it's also not a microcontroller but an FPGA. The contents of the package is different, but the contents of the package also changed during Commodore's own production runs e.g. the change from 6526's to 8521's.
First of all neither FPGA's nor MCU are not going to "react the same way to electric signals", cause contrary to what many think, FPGA's are not tabula rasa you can put any digital design to - there are limitations to what can be synthesized. Secondly, 6526 to 8251 is not only period correct, but also a change made by manufacturer themselves, therefore has almost zero historical impact.
There is no way a new design, with almost everything replaced by FPGA's can be called Commodore 64, as much as a Ford-T with a brushless electric motor and lithium baterries can be called Ford-T. You can call it replica, and sell it to those who to pretend they own a historical car, but for everyone who truly understand value of old and antique, that would be laughable.
No, I understand it, but yes, I think it is absolutely bizarre. Both can be true at the same time. To me the value in an original over a replica is purely whether or not a bunch of purists are willing to pay more for the original, which I find both bizarre and hilarious. To me the original has no additional value over the resale value - if anything it's value may often be lower if I suspect its age means a higher risk of having to replace components down the line. So, sure, if I were to buy one for the sake of potential financial value I'd value original, working parts because I know some proportion of others care. But if I bought one to use and found some parts had been replaced, I wouldn't stop calling it a Commodore 64 whether or not the replacement parts were original.
But in this case, the price for a Commodore 64 is still low; not even purists are willing to pay much for them.
> First of all neither FPGA's nor MCU are not going to "react the same way to electric signals", cause contrary to what many think, FPGA's are not tabula rasa you can put any digital design to - there are limitations to what can be synthesized. Secondly, 6526 to 8251 is not only period correct, but also a change made by manufacturer themselves, therefore has almost zero historical impact.
For the fidelity required for a 6526, it very much is reacting close enough or it wouldn't work as a drop-in replacement. I don't care if there's some sort of deviation that is small enough that it has no relevance to it's correct functioning in the real hardware. As for "period correct", I couldn't give the tiniest little shit, as the long as it works, as unlike the SID or VIC, there's no "works correctly but the output is different enough to affect my enjoyment of the machine".
> There is no way a new design, with almost everything replaced by FPGA's can be called Commodore 64, as much as a Ford-T with a brushless electric motor and lithium baterries can be called Ford-T. You can call it replica, and sell it to those who to pretend they own a historical car, but for everyone who truly understand value of old and antique, that would be laughable.
Of course there is every way in which something with everything replaced can be called a Commodore 64: All it takes is people choosing to do so. For me, whether or not I'd call it a Commodore 64 would come down to a subjective assessment of how similar it is. If you changed the physical appearance, that'd be a no for me, but replacing a part that doesn't affect the way the machine works? Sure. I wouldn't try to pass it off as an original, but I also wouldn't care one bit that it's not original, because I don't have any interest in a "historical artefact" but in the nostalgia of being able to use something which feels like the original.
Enjoy your electric Ford-T!
A connection to history is irrelevant to me. Something which triggers my nostalgia and which I enjoy using is not, and that does not require perfect accuracy (if anything, nostalgia often favours avoiding perfect accuracy on favour of avoiding nuisances)
I certainly do have no interest in "investing", no, because investment or history is not the point to me.
If I had the choice between an electric Ford T and an authentic one, I'd certainly prefer the electric one. That's be an interesting curiosity - Ford worked on one which was never launched, and his wife drove an electric car -, while an original one would be something I'd have no interest in outside a museum.
BTW, good luck reselling your model T as actual model T LOL.
Reselling an actual model T with an electric motor as an actual mode T with an electric motor would work just fine. Some would lose interest because it's been changed, some would find it more attractive. For my part, I'd find it far more interesting and be willing to pay more for something esoteric like that.
Using the actual hardware with 100% accurate modern part replacements is one way to get there. Another way is to have perfect, "cycle accurate" emulators but these aren't easy to come by - some emulators have been in development for years and still have glitches. This kind of hardware replacement has a much higher chance of reaching the 100% accuracy I'm referring to.
There are other similar projects. This notion that the use of FPGA's means there's some inherent difference in fidelity that newly made silicon wouldn't have is nonsense for parts like this that are so far from pushing the limits of available FPGA's.
Arguably an emulator could do the same, but it's much harder to simulate the entire system than it is to isolate a single chip and emulate that.
But also keep in mind that there is no such a thing as a "digital circuit" in physical world, because there some analog effects at work in any digital circuit. If it were not true, the would not have been hardware incompatabilities seen even in moderrn systems, which often happen due timing/delay or noise issues. WRT to retro tech, in for example Apple-I modern 74hct/act chips would not often work compared to more humble 74ls chips. There are also interesting temperature-dependent effects in NMOS 6502 (some undocumented instructions are executed differently) which have non-digital reasons and cannot be reproduced.
Emulators are a lot easier btw to write than a VHDL or verilog spec and put it to actual hardware and debug etc, due to having already so many existing open source code for emulators, processors etc.
My point is different though - there is no way to make new Commodore 64 out of existing components. What you will get is a faithful replica with zero historic importance. For some it does not matter, but I still believe that even these people make a majority, the resulting product is not C64 and should not be called such.
1) The historical artifact. Case manufactured in original factory, IC's manufactured back in the day under (in this case) Commodore's supervision, etc.
In this case,"original condition" is paramount. Some may be happy with minor fixups like replacing electrolytic capacitors, power supply, broken connectors, replace dead IC or whatever. Some may want as original as possible, in working order or not.
2) The look & feel, having original-looking machine in front of them, that (as much as possible) connects to the same peripherals original machine does. And runs software exactly like original machine would.
In this case, most buyers won't care (or even prefer) various upgrades / replacements, as long as that look & feel remains. See eg. CPLD or FPGA based replacement parts, new keyboards, or "mini" versions of systems like the NES. That C64-in-a-joystick or similar is grey area here. :-)
I suspect user group pursuing 2) is larger than those pursuing 1). Let alone the purists among them.
Software emulators are just a lower-bar, easier way to tip one's toes in the water (or do sw development).
In any case I would agree with title "100% new C64" if it were made from silicon level replica of chips, not FPGA's, much like new 6502 sold on aliexpress are generally good replicas of NMOS 6502, with the quirks and even current consumption faithfully reproduced, not some Xilinx Spartan-based simulacrum of the real thing.
The logic could as well be implemented in software - the reason it isn't and it wasn't in the original C64 is because it was not possible then. Programming this logic on a CPU would have required a very fast microcontroller, that would probably be more expensive than the whole computer. Even today, not many MCUs would be capable of emulating the CIA and keep up with all the timings. Mind you there is a difference in creating a software emulator that runs within the host computer versus emulating a chip that responds in real time to the electric signals.
Aftermarket / modern replacement parts cater to a different market. They don't 'dilute' the historic value of original parts.
There is considerable overlap though. If anything, availability of modern replacements eases demand for original parts. Helping to keep those available for purists, musea, reverse engineering etc (and their prices reasonable). This should make both purists & non-purists happy.
In any case a "Commodore 64" made entirely from components invented in 2020s should be called C64 anymore. It is a replica, a decent one, but not the real thing.
Want to have it collecting dust in a museum? Sure, you're going to want the original. Nobody is interested in an FPGA for that.
Want to actually use it? If an FPGA is close enough that it is literally impossible to tell the difference in a black box comparison, for all intents and purposes it is the original. Emulation simply isn't accurate enough for that, but FPGAs can be 100% cycle-accurate. And this means you don't need to risk wear or damage on your genuine C64 just to experience what it is like to use a C64.
The newly-made design, be it in FPGA or ASIC form, is not the original MOS chip. But it could indeed behave identically.
ASIC advantages such as lower power consumption and higher achievable clock speeds at a given node, are advantages relative to the FPGA. Not advantages relative to the original MOS chip, which dirt cheap FPGAs can vastly outdo, and only need to match for the purpose.
Honestly it would have been cool if they added a battery and maybe an extra register to indicate its presence; having the TOD clocks keep their time between power cycles would be cool.
Edit: If replacing a dead 6526 I would keep the dead one too. :)
FPGAs are not emulation. They implement logic at just as low a level as an ASIC. One day even working original C64s will stop working. You can't get original parts anymore. This is as good as it gets for fixing those.