[HN Gopher] J-CIA64 - Modern spare part for Commodore 64, Commod...
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J-CIA64 - Modern spare part for Commodore 64, Commodore 128, SX-64
Author : dusted
Score : 209 points
Date : 2023-08-09 09:07 UTC (13 hours ago)
(HTM) web link (1nt3r.net)
(TXT) w3m dump (1nt3r.net)
| nxobject wrote:
| Anyone up for a Heathkit-style "learn as you build your own C64"
| kit?
| snvzz wrote:
| A replacement, yes. But is it open hardware? It doesn't seem to
| be the case.
|
| This is unlike the recently released VIC-II Kawari[0]. That one
| is OSH proper.
|
| 0. http://accentual.com/vicii-kawari/
| dusted wrote:
| The guy has worked on a complete chipset replacement for a very
| long time, I could understand if he would want to earn some
| money for his efforts before open sourcing it, he's under
| absolutely no moral obligation to opensource this, but I figure
| he might some time in the future, if people are nice to him.
| You know what's also not OSHW ? The FPGAs running it
| nullsmack wrote:
| Who cares if the FPGA is opensource? If the verilog, or vhdl,
| or whatever was used to program it was available someone
| could adapt it to other chips.
| rasz wrote:
| https://github.com/bwack/VHDL6526
| the_af wrote:
| Tangentially related, and given some of the debates in the
| comments below, I'm sure I'll be burned at the stake for this,
| but here I go anyway:
|
| 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!
| flyinghamster wrote:
| Much like how I've gotten onto a PDP-11 kick - yeah, it would
| be neat to have my own 11/70, but the power and space
| requirements would be insane, I'd have to track down rare and
| expensive pieces, and I don't have quite the skill set to
| debug/repair old hardware to the component level. SIMH it is
| (and it has a zillion other emulators as well).
|
| 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.
| bitwize wrote:
| You may wish to consider the PiDP-11, a frame that replicates
| the PDP-11's blinkenlight panel, into which a Raspberry Pi
| running SIMH or similar can be installed. Attach a terminal
| with a USB-to-serial adapter, and the experience is complete,
| without the drain on power, space, time/effort, or money.
| It's like THEC64 for the DEC mini world.
| 300bps wrote:
| It's really awesome how different people are able to engage in
| this hobby with different requirements.
|
| 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.
| II2II wrote:
| I don't think anyone will burn you at the stake! Real hardware
| is great for diehard enthusiasts, for those wanting to use old
| peripherals, and for people wanting to play with electronics.
| Emulation is great for nearly everyone else.
| jwr wrote:
| I'll plug the Ultimate 64
| (https://ultimate64.com/Ultimate-64-Elite) -- it's a hardware-
| emulated C64 that you place inside your breadbin case. It works
| unbelievably well and is a great modern replacement with a lot
| of convenience added. For example, you don't have to deal with
| weird PSUs (12V runs it just fine), you get a HDMI output with
| sound (can be from a real SID!), and the HDMI out has _no
| delay_. That 's a big deal: all the emulators normally use
| framebuffers, so you get a delay, none of the games were built
| for it.
|
| 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.
| reaperducer wrote:
| The problem is that the Ultimate 64 has been out of stock for
| a very long time. I check every few months, and have never
| seen it available.
|
| And even when it might be available, you can get two or three
| real C-64s from eBay for the same price.
| the_af wrote:
| Thanks! It looks awesome and better but also more expensive
| (and slightly less "out of the box") than TheC64, at least
| when I got mine.
| macjohnmcc wrote:
| You can also use TheC64 (Max) as a USB keyboard to the PC to
| use in Vice if you decide you want the keyboard and want to
| take advantage of some of the functionality of the emulators. I
| found a page that shows how to add a USB connector to the Max
| to allow this.
| the_af wrote:
| Never thought of this. Looks useful! I will look it up.
| technothrasher wrote:
| I enjoy owning the fourth earliest serial number C64 registered
| on the C64 registry, and last I tried it still worked. But
| honestly I wouldn't ever really think of actually using it or
| any of the handful of others I have. Whenever I'm in the mood
| to play, I use an emulator.
|
| 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.
| TacticalCoder wrote:
| > I've given up on owning a real C64
|
| 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.
| bitwize wrote:
| I'm also a THEC64 owner, and I call it "retrocomputing on easy
| mode". That's a good thing! It offers a good-enough simulacrum
| of what the C64 experience was like. The breadbin case with
| original-layout keyboard, which feels plausibly like one of the
| keyboards that shipped on actual C64s (there were a few
| different ones), really put THEC64 over for me. And it just
| works with modern equipment like HDMI displays and USB
| controllers. It's a great way to introduce kids to the way we
| computed back in the before times.
| dusted wrote:
| A Pi400 is also an excellent option in my opinon. I love doing
| both real hardware and emulation for different purposes, I
| don't see anything wrong with picking either, neither or both
| (neither of course is the worst option ;) )
| the_af wrote:
| I considered the Pi400 but, like I said, the C64 keyboard was
| a big deal to me. Otherwise I would just use VICE on my
| laptop :)
|
| 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 :)
| icedchai wrote:
| I like both. The software is so much more convenient with
| emulation, but seeing the real hardware feels like it takes
| you back in time...
| the_af wrote:
| TheC64 goes a long way into fooling you. Barring minor
| details (especially in the connectors and peripherals) it
| looks like a real C64! It delivers _most_ of the nostalgic
| experience for me.
| gmerc wrote:
| MiSTER is pretty much a perfect replacement.
| the_af wrote:
| Curious: does MiSTER have a fully working C64 keyboard
| lookalike with no extra work that I must do, out of the box?
| If not, it's not what I was looking for :)
| Damogran6 wrote:
| We're going to have ironically hip webapps in the future, aren't
| we?
|
| "100% Amiga generated web content"
| LordLotherak wrote:
| To me at least, it makes much better sense to go all-in on a
| MiSTer, rather than gradually frankenstein-ing the build with ARM
| or FPGA-based chips. There's money to be made trying to maintain
| these 40+ year old units though. (if the cottage industry
| surrounding it isn't a clue)
| dusted wrote:
| I have an Ultimate64 too, I did this project for philosophical
| reasons, since everything is new, even the motherboard, it's
| definitely a new machine, but at the same time, if you look at
| the electrical activity on the traces, you would conclude it's
| a c64, and yet, there's no commodore chips on there.. The most
| commodore thing is the firmware which is on the UV EEPROMs, and
| even that is slightly different since the original machine used
| mask roms rather than writable roms. So, it's very much not
| about "sense" on a practical level (then VICE with a couple of
| Quickshot competition pro USB sticks makes the most sense)
| jwr wrote:
| > there's no commodore chips on there
|
| My Ultimate 64 has a real SID in a socket :-)
| SomeoneFromCA wrote:
| No, it is not Commodore 64 anymore. It won't feel like one, you
| can as well run an emulator. I get it, FPGA is more faithful
| reproduction, than pure software, but it is not a real thing, and
| will never be.
| TonyTrapp wrote:
| I wouldn't equal the possibility of taking a C64 with one or
| two broken chips and replacing them with a cheaper, more
| reliable modern equivalent to tossing the whole machine away
| and going 100% emulation.
| SomeoneFromCA wrote:
| Neither would I, but this is not what the title says.
| dusted wrote:
| FPGA is in absolutely no way more faithful, which FPGA
| implementation has 100% compatibility with all internal and
| external interfaces ?
| crote wrote:
| That completely depends on your use case.
|
| 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.
| SomeoneFromCA wrote:
| Emulation is very close to 100% cycle accurate for many, many
| machines. You would practically not deal with this problem
| anyway. Now, I may want to tinker with my computer on a board
| level, making a period-accurate hardware-tweaks for the
| machine, how exactly I'd accomplish that, if everything is
| just a big FPGA? Now, having IC'level FPGA substitute for big
| chips on the original board is a bit better than one big flat
| fat IC, but it still a different machine and cannot be called
| C64, as much as a Ford-T is not a Ford-T if you put a modern
| electric motor to it, even if you tweak it to sound and
| handle exactly like T does.
| tyingq wrote:
| I don't know that for a parallel/serial/rtc chip you would
| really see any difference. I can see your point for some of the
| harder to emulate parts like the SID.
| snvzz wrote:
| Once configured, a FPGA is the hardware that's configured into
| it. It's cheaper than an ASIC, unless you make a shitton of
| them.
|
| 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.
| nullsmack wrote:
| This is a silly argument.
|
| 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.
| rasz wrote:
| the Audiophile argument
| tenebrisalietum wrote:
| The 6526 is infrastructure--it's a timer, clock, and I/O chip
| and doesn't really have anything to do with the interactive
| look and feel of the system. So an FPGA here doesn't harm the
| C64's soul one bit, if it works exactly like the original.
|
| 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.
| :)
| nemo8551 wrote:
| Well that's just like your opinion man.
|
| 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.
| vidarh wrote:
| For e.g. the SID, where a bad implementation might work but
| affect the sound, you might have a point, but for the CIA's
| this a meaningless purity test and sophistry.
|
| 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.
| SomeoneFromCA wrote:
| No, it is not "sophistry". There is a reason why Apple-I
| commands these high prices- because it is a piece of history,
| a slice of technology of the era. If I buy Commodore 64, I
| won't be buying it for replaying old games, it is completely
| pointless excercise, I can just buy RPi for that, I will be
| buying it to have a historical artifact. Now what kind of
| historical artifact would it be, if the only thing left is
| the PCB, and everything else are Xilinx IC's designed in
| 2020s, 40 years later?
| RetroTechie wrote:
| You pay for some combination of:
|
| 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).
| [deleted]
| SomeoneFromCA wrote:
| Your assumption is unjustified TBH, because HN comment
| section is not representative of retro community. Now I
| also cannot understand how something can feel same as old
| historic device - this is not true even for differen gens
| of the same hardware. Say Apple-IIe feel substantially
| different from IIc and deeifferent generations of Sony PS
| 1 are also feel different.
|
| 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.
| vidarh wrote:
| The retro community is what drives the demand for these
| replacements.
| SomeoneFromCA wrote:
| Because there is no modern period-accvurate replicas.
| There is a reason NOS components command high prices.
| vidarh wrote:
| That might be an argument if the only market was for
| projects like the linked one, which provide drop in
| replacement for period-accurate replicas, but the market
| is also full of full FPGA reimplementations and machines
| that adds all kinds of additional features, which shows
| there's a substantial portion of the retro community who
| don't care even about whether the result provides
| accurate reproductions.
| SomeoneFromCA wrote:
| This is not a market for retro, it is a market for
| replicas, an entirely different one. Still a replica is a
| replica, and should not be advertised as a brand new
| original machine, which the original title (before edit)
| was about.
| glimshe wrote:
| There are 2 things you can get from classic computers - a
| piece of history as you say, but also nostalgia and a
| return to childhood. I don't think that replaying old games
| is a pointless exercise. It's just a way to escape from the
| day-to-day grind and go back to an earlier part of life
| where things were just a lot easier. So I hear what you
| want from computers, but there is a lot more to
| retrocomputing than just hardware preservation.
| SomeoneFromCA wrote:
| Totally agree with you; my point is that for replaying
| old games, RPi is well enough. No point in making what is
| esentially a hardware emulator and calling it "the real
| thing".
| glimshe wrote:
| Ah, I see. On that, there are different degrees of
| "realness". Aside from historical preservation, there are
| enthusiasts (I might be one of them :) ) who want the
| most realistic possible retro experience given the
| constraints of ageing hardware.
|
| 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.
| SomeoneFromCA wrote:
| The problem is that FPGA's are not 100% hardware replicas
| of the chips. The only way to be close to tru experience
| is to use newly made silicon, but made according to the
| blueprints from 1970s. For example 6502s sold today are
| of this type; also 74AC/HC/LS chips.
| vidarh wrote:
| These are for the most part digital chips. If you make a
| cycle accurate replacement, they're _close enough_ in
| that they for most users won 't change the output. E.g.
| here's an in-progress cycle accurate 6510/8500
| replacement, that is if anything _more_ compatible than
| some of the alternative "period" _licensed_ 6502
| /6510/8500 designs, where support for the undocumented
| instructions vary:
|
| https://1nt3r.net/j-cpu/
|
| 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.
| glimshe wrote:
| They are not hardware replicas (as in "the same
| circuits"), but as far as the pin voltages are concerned,
| they can behave _exactly_ like the original chips. And
| when I say "exactly", I don't mean "pretty much the
| same", I mean _the same_. That 's the beauty of the
| digital world, it's absolutely possible to fully and
| perfectly emulate digital circuits.
|
| 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.
| SomeoneFromCA wrote:
| It is not the point that replica behaves "perfectly
| same", the issue is that they are not period accurate.
| Even it is a perfectly
|
| 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.
| stOneskull wrote:
| as long as you don't have to load games using the
| datasette. haha.
| vidarh wrote:
| If you're buying it as a historical artefact and not to use
| it, then surely it doesn't matter if it's non-functional
| either? In that case this isn't for you, and that's fine,
| but arguing it's not a Commodore 64 any more is sophistry.
| It's not an "100% original unchanged" Commodore 64, sure.
| Very few people care about that.
| SomeoneFromCA wrote:
| Working historical artifact are way more valuable then
| non-working. I am surprised so many people do not
| understand that.
| vidarh wrote:
| I understand that it is so, I don't see the point of it.
| It's not an asset that appreciates at a rate sufficient
| to make it worth it for the value, so it's then down to a
| purity test. To me they've no appeal as a historical
| artefact. Their only appeal is for nostalgia, for which
| being able to actually use them matters far more than
| purity - if anything, my experience is that nostalgia is
| best served by imperfect replication that fixes those
| real aspects that were particularly painful (like easily
| burning out 6526's...). Especially those we badly wished
| for at the time (like 6526's more resistant to
| burnouts...)
| wkjagt wrote:
| I agree. And it's not just about monetary value. There's
| just something beautiful about a 40 year old computer
| still working perfectly. The fact that it's all original
| is almost a necessity for me to enjoy it to its fullest.
| I love programming these old machines in assembly
| language, while at the same time doing my best to
| understand what is going on inside the machine with each
| instruction. Replacing original parts with
| microcontrollers would take away a lot of that pleasure.
| SomeoneFromCA wrote:
| precisely my point. I would certainly buy an Apple-1 if
| it were not as pricey as it is now.
| vidarh wrote:
| If you want to use them, why does it matter if a chip has
| been replaced? To me, _that_ is what is bizarre. I get
| the appeal of preserving some. I get the appeal of using
| some. I don 't get the appeal of insisting on purity and
| retaining only original parts for something you want to
| actually use, especially when that increasingly means
| being unable to use these machines because parts are
| becoming harder to find.
|
| > 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.
| SomeoneFromCA wrote:
| I think it must be bizarre for why people want original
| artwork, and do not value replicas. You folks,
| _bizarrely_ fail to understand what is _historical value
| _ and what is _period-correct_ _substitute_.
|
| 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.
| vidarh wrote:
| > I think it must be bizarre for why people want original
| artwork, and do not value replicas. You folks,
| _bizarrely_ fail to understand what is _historical value
| _ and what is _period-correct_ _substitute_.
|
| 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.
| SomeoneFromCA wrote:
| Very funny mix of GenZ and postmodern thinking - from
| GenZ it is like "I want to signal to everyone (myself
| including) my connection to history without actually
| investing into, by buying an insta-history new thing" and
| from postmodern -"things are what I decide to call them,
| if I call apple a banana it is a banana" now.
|
| Enjoy your electric Ford-T!
| vidarh wrote:
| I don't care about signalling anything to anyone. I grew
| up with a Commodore 64, and to me the value on a
| Commodore 64 is primarily nostalgia.
|
| 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.
| SomeoneFromCA wrote:
| Then you should get worked up so much, about not calling
| it C64. You should be fine then it is not Commodore 64,
| but just a gimmick that has nostalgic value for you, but
| not in any way actual Commodore 64 (which it clearly is
| not).
|
| BTW, good luck reselling your model T as actual model T
| LOL.
| vidarh wrote:
| I don't care what you call it, but to me it's still a
| Commodore 64, and not a gimmick, and I could just as well
| tell you not to get so worked up over someone else not
| caring about your purist insistence it is not.
|
| 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.
| SomeoneFromCA wrote:
| I not being worked up about your opinion, you are
| entitled to. What I am saying that it should not be
| advertised as a real thing, as a brand new C64. As simple
| as that.
| wkjagt wrote:
| If an original part is unavailable, yeah, I'd replace it
| with a more modern replacement. I prefer that it remains
| functional more than keeping it 100% original. But I
| would still first try to find an original part. And I'd
| feel somewhat disappointed, and the computer would feel a
| little less appealing to me, if I could only find an FPGA
| based replacement. I know that's bizarre, and I can't
| rationally explain it, so I guess I agree with you in a
| way.
| vidarh wrote:
| I can get preferring to stick to "real" parts if
| available, even though it's not something I really care
| about. I draw arbitrary lines too, I just generally feel
| it's worth being pragmatic about them if the alternative
| is losing functionality, which it sounds like you are
| too.
| SomeoneFromCA wrote:
| No it is not bizarre, it is normal and typical feeling in
| retro community. Check prices on Apple-I or NOS analog
| components. I'd say it is quite unusual to be indifferent
| to the period accuracy among those who are interested
| retro tech.
| bullen wrote:
| 100% agree
| rcarmo wrote:
| Last time I wanted to fiddle with a C64, I just went and
| flashed bmc64 (https://github.com/randyrossi/bmc64) to an SD
| card. Even an original Raspberry Pi 1 does a decent job of
| emulating it.
| SomeoneFromCA wrote:
| Exactly mt point, no point in buying a bunch of Xilinx FPGA's
| and calling it Commodore 64.
| wkjagt wrote:
| I think the point of the J-CIA is to replace a failing CIA in
| an actual C64. However, that's not what the title of this HN
| post is about, so I'm not sure what is going on. Regardless, I
| think making a replacement CIA is very cool, noble even, and I
| would be happy to buy one if a CIA in my Commodore failed, if
| it meant having a useable C64 instead of an unrepairable one.
| But I do agree with you, that building a completely new C64 out
| of FPGA replacement parts would feel very weird to me. I
| wouldn't feel like it's the real thing, even if it behaves
| exactly like one. The big advantage though, if it's a 100%
| faithful reproduction, would be that it physically behaves like
| the real deal, meaning you can plug in actual cartridges, build
| things that connect to the user port, etc, which are things you
| can't do on an emulator. For now though, I'm just happy mine
| still works (even though I kinda want to get a C64C instead of
| my bread bin).
| SomeoneFromCA wrote:
| Oh, yes I agree. It is a necessary compromise, much like
| removing Rifa and electrolyte caps. I would still preserve
| the original broken IC in the C64's empty internal space,
| secured somehow, to keep the history intact.
| varispeed wrote:
| It is the real thing. It does the same thing, just using
| different technology. It's a fully digital chip, so it doesn't
| matter if logic is fixed on the die or "fused" on FPGA. It does
| the same function.
|
| 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.
| SomeoneFromCA wrote:
| I do not need this condescending lecture about the merits of
| programmable logic over CPUs and emulation. The difference is
| not technical or even technological; the actual difference is
| social. Anything that it is not period-accurate is going to
| erode the historical value of the artifact, until the point
| when everything inside is a bunch of fpga's on sockets.
| RetroTechie wrote:
| The value of "historical artefacts" is determined by how
| many specimens remain, and how sought after they are. For
| whatever reason.
|
| 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.
| SomeoneFromCA wrote:
| No need in italic font and other passive aggressive
| stuff. Ask any old hardware enthusiast if they prefer an
| actual exact silicon level replica of SID or modern fancy
| shmancy FPGA replacement thing - I guarantee you majority
| would want the precise replica. Because why people
| content with these FPGA ugly looking quasi-substitutes,
| cause there is no actual period-accurate substitutes are
| available.
|
| 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.
| rasz wrote:
| wonder if relate to bwacks https://github.com/bwack/VHDL6526
| https://www.youtube.com/watch?v=FLxncR7Ru4Y
| twarge wrote:
| Which FPGA is it?
| tyingq wrote:
| The image is too low-res to see the model, but you can see the
| Lattice logo. This picture[1] is a little better, but still
| pretty grainy. Best guess is "Lattice ICE5LPxx", where I can't
| quite make out what the "xx" is. Maybe ICE5LP1K ?
|
| https://retro8bitshop.com/wp-content/uploads/2023/08/F2eV4mB...
| semireg wrote:
| Am I the only one with a twang of dread and anxiety... being
| transported back to a summer weekday in the 1990s. I was maybe 8
| years old, learning how to use a screwdriver to take things
| apart. I opened my C64, wiggled one of these ICs out, breaking
| the pins in the process. Oh... having to explain this to my
| parents. They were not happy. I'm pretty sure that was the end of
| my GEOS days.
| johnklos wrote:
| Retro Recipes did a whole video about this very thing:
|
| 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 :)
| dusted wrote:
| I think I've plugged this before, but I have bought the part and
| it's working in my "MaxFake64" project, only thing left from
| Commodore is the keyboard http://dusted.dk/pages/c64/MaxFake64/
| wkjagt wrote:
| Very cool project! I hope you do the keyboard too, because (in
| my opinion) that's the worst part of the C64. I see you're
| building the C64C form factor. I don't know if that has a
| different keyboard than the bread bin I have, so maybe yours
| already has a better typing experience than mine. And even if
| it's the same keyboard, the lower profile of the case must
| already make a huge difference. But building a nice keyboard
| for it with good switches will still make a big difference.
| dusted wrote:
| I'll definitely do the keyboard, actually I'm using the
| breadbin keyboard here because I think it looks neat.
| Commodore were pretty good at keeping things compatible. The
| motherboard was intended for breadbin as well, but fits fine
| in the C case.
| wkjagt wrote:
| How do you like typing on it? I wonder if I dislike typing
| on my breadbin only because of the height of the case, and
| the position it puts my wrists in.
| dusted wrote:
| I find it perfectly fine and acceptable for long periods
| of time, I think the original keyboard is quite good
| mechanically (springed keys with conductive rubber feet
| onto pcb pads), the ergonomics of the breadbin (I have an
| ultimate64 and a few real ones) is not my cup of tea, it
| ends up hurting my wrists after longer sessions, no such
| problem at all on the C64c models.
| wkjagt wrote:
| Hmm maybe I'll put a C64C on my list of "things to buy if
| they happen to pop up at a reasonable price".
| codeflo wrote:
| What do they do about the SID?
|
| 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?
| wkat4242 wrote:
| It's not impossible. We still make many analog chips. Opamps,
| power amps, signal processing.
|
| 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.
| dusted wrote:
| I'm personally pretty happy with the ArmSID, thing is, it does
| not sound like my 6581R3.. BUT! My 6581R3 also does not sound
| like my other 6581R3, there's not really any "one true" sound
| for the SID, for better or worse.
|
| 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 ^_^
| RetroTechie wrote:
| > BUT! My 6581R3 also does not sound like my other 6581R3,
| there's not really any "one true" sound for the SID, for
| better or worse.
|
| 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.
| dusted wrote:
| I guess we can never know, but I strongly suspect they've
| never sounded the same, similar, but not the same.
| bartread wrote:
| That's not true: you make the SID sound weird and exotic when
| it's really not (although it is incredibly cool).
|
| 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)._
| taylodl wrote:
| > I'd go as far as to say that Commodore missed a massive
| opportunity with the Amiga in terms of use for music
|
| 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.
| criddell wrote:
| Didn't the Atari ST own the DAW space at that time?
| reaperducer wrote:
| The ST ate everyone else's lunch (in the DAW world)
| because it had built-in MIDI.
|
| In a world where the Amiga didn't need an external MIDI
| interface, I suspect things would have been different.
| taylodl wrote:
| Well, they did have _Creator_ which went on to become Pro
| Tools. As I recall, its big thing was MIDI sequencing
| whereas the stuff for the Amiga was more content
| creation-oriented. Add in the fact that the Atari ST was
| cheaper and I guess that was that!
| diydsp wrote:
| It actually is weird and exotic. The analog SVF filter is
| made with digital components and is highly nonlinear. No one
| fabricates these any more though it would be technically
| possible.
|
| 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.
| CalRobert wrote:
| If you enjoy this stuff, https://c64audio.com/ is well worth a
| look. Some good stuff from only 25 years ago at
| https://archive.org/details/back-in-time-1/Back+in+Time+1/Ex...
| .
|
| I was really into Koyaanisqatsi at the time and you'll
| definitely hear the influence there.
| vidarh wrote:
| Digital emulation, yes, like the ArmSID[1] which lets you tune
| the output to what _you_ expect a SID to sound like, because
| they didn 't all sound the same either, which is part of the
| problem of "accurately" replacing it - they were never accurate
| to begin with.
|
| [1] https://retrocomp.cz/produkt?id=2
| fluoridation wrote:
| They were accurate, just not precise. ;)
| jwr wrote:
| Good news! The 6526 was always easy to damage through static
| discharge, by touching or plugging something into the user port.
| stuff4ben wrote:
| I question why people go through the trouble of doing this. Then
| I remember back to when I was a pimply teenager, lugging my C64,
| 1541, and 13" TV to a user group meeting on a crisp Saturday
| morning. We would share warez and see awesome demos and oogle the
| C128's and inevitably someone would bring an Amiga. We'd gather
| around while they played the latest games and show off the full
| capabilities of that machine. We had some Apple users there too
| with their IIe's and IIc's. I never saw a Mac in real life until
| much later in college. And that's a part of my life I'll likely
| never live again, but now I get why people want to build these
| machines today, for nostalgia.
| fallat wrote:
| Not just nostalgia. I want to experience what the first
| personal computers were like. I think there's a lot of value
| there!
| progman32 wrote:
| Agree. I was born way after the C64 came on scene and never
| touched one until I bought one ten years ago. I'm in it for
| the perspective it brings (and I like fixing things).
| bobboies wrote:
| I also believe there's some value in reassessing how systems
| like that function. There's some value in a challenge like:
| what can you do on older hardware with todays knowledge?
| Maybe there's something to be learned and applied to modern
| problems.
|
| 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.
| myself248 wrote:
| I think an underappreciated value of growing up in that
| era, was that the entire machine, top to bottom, was simple
| enough that a single person could understand it. Without
| even making it their life's work. There's simply nothing
| today like that.
|
| 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.
| irisgrunn wrote:
| The Commander X16 and Foenix F256K are new machines that
| you could comprehend completely. I don't really want to
| call them modern though.
| icedchai wrote:
| I still remember the first time I played a couple of Psygnosis
| games on an Amiga 500: Blood Money, and Shadow of the Beast.
| Those two blew me away. The sound and the graphics were
| absolutely stunning for late 80's.
|
| 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.
| dylan604 wrote:
| >And that's a part of my life I'll likely never live again
|
| 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.
| dan_quixote wrote:
| Assuming continued forward progress, this feeling is true of
| each generation. But when I get nostalgia about all the
| progress the world made since my early childhood in the
| 80s...I think about my great grandfather who was 8-ish when
| the Wright Brothers made their first flight, 40s when the
| atomic bomb was developed, 73 when the first man walked on
| the moon, and then lived another 20 years!
| bitwize wrote:
| Retrocomputing isn't _just_ about nostalgia, a midlife-crisis
| rewind back to your pimply-faced youth. People are _still_
| getting more out of those old systems than was ever thought
| possible back in the day, using powerful modern systems to
| solve for packing ever more complex code or data structures
| into 64k or less. Kids are being introduced to old platforms.
| They can 't deliver the graphical fidelity of the Xbox Series
| S, but if Minecraft and Roblox are any indication, post-zoomer
| youth do just fine with simple, abstract, representational
| graphics.
| jchw wrote:
| Wow, I thought this already existed in some form, but it turns
| out it was actually the PLA that I was thinking of.
|
| >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.)
| dusted wrote:
| Yes, I put mine in low-profile zif sockets, additionally, I put
| ESD protection diodes on the joystick ports because that's
| where you're most likely to touch and fry (including the
| orignal sid and cias)
| jchw wrote:
| What's the advantage of low profile sockets? Sounds
| convenient, but I just used pretty ordinary DIP sockets. (At
| least I have a puller to get chips out now though; jimmying
| with a flathead screwdriver never felt great.)
|
| 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.
| dusted wrote:
| I wanted ZIF sockets for three reasons things: I want to be
| able to swap out chips (and their fake replacements) easily
| to test compatibility and stuff like that. The chance of
| breaking the pins off of the vintage chips is very real,
| especially with repeated pulls/pushes. They also put a more
| constant pressure on the pins, so they _should_ have less
| of "popping out" the chips, which the wipe-contact type of
| sockets do a bit sometimes.
|
| 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
| lmpdev wrote:
| I have a boxed C64 that hasn't been turned on for over 20 years
|
| 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
| HPsquared wrote:
| Can't you just use some filtering caps? (spoken as a non-EE)
| dusted wrote:
| You can do it with a linear supply, a common mod that people do
| is actually to replace the lm7805 regulator with a pin
| compatible switching replacement for less power draw and heat
| generation.
|
| I think ripple-free is by 1982 standards ;)
| jwr wrote:
| The PSU also supplies 9V AC (this is not a mistake). The C64 is
| quite sensitive to over-voltage, so your switching supply might
| work, or it might kill it because there are voltage spikes
| which modern equipment doesn't care about, but the C64 will.
|
| 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.
| biggieshellz wrote:
| Why would you blow it up with a SMPS? I built a PSU for mine
| with a 5V switch-mode wall wart that originally powered a USB
| hub and it works fine. There's a 100uf filter cap on the 5V
| rail inside the machine already that will smooth things out.
| The real danger is letting the 5V rail get too much over
| voltage; that's what happens with the original power supplies,
| and it will cook the RAM chips in a hurry.
| unwind wrote:
| You are probably aware, but replacement PSUs are fairly widely
| available [1].
|
| I am no EE but I would be very surprised if they are linear.
|
| [1]: https://www.c64psu.com/
| lmpdev wrote:
| Edit: Do NOT use LM7805s in parallel, they don't load balance
| evenly
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