MEGA65 FORUM

Another c64-ish motherboard in development.

append delete Solei

Seems like Gideon - the maker of the 1541 ultimate cartridges is quite far in the process of making an all new enhanced replacement c64 motherboard:

http://1541ultimate.net/content/index.php?option=com_content&view=article&id=74&catid=9

And to stir things up a little - the ultimate64 even got a socket for a real sid chip, something that the Mega65 should also have onboard as originally planned (IMHO).

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append delete #1. gpz

we'll see how good his core really is when the hype is over... making a board is the easy part of the process :)

append delete #2. Daniël Mantione

Well, Gideon already has from his 1541U2:
* CPU
* VIA
* SID

His CPUs and VIAs are highly compatible. Going from VIA to CIA is not that big of a step. His main challenge is to design a VIC II with good compatibility.

... which is a far from trivial task. But he is experienced enough to do it.

I think the main worry is that there are now 3 FPGA mainboard projects:
* Ultimate 64
* C64 Reloaded mk3
* Mega65

Of course, each targets a slightly different audience, but on the other hand, people will need to choose. Personally I think the Mega65 is still the most interresting one, but the other have their merits as well.

append delete #3. gpz

Going from VIA to CIA is not that big of a step.

oh oh. they are totally different :)

and yes, no doubt he can pull it off - it will take years however.

append delete #4. gardners

Well, I think the interesting thing will be if he is willing to open-source his efforts. At the moment it is crazy that there are multiple closed implementations of the VIC-II. It really works against preservation of the platform, all for the hope of short-term advantage.

We'd certainly be willing to cooperate with Gideon on jointly creating an open VIC-II core that was as perfect as possible. That way in the least we can potentially cut the time required in half or better.

I'd also still like to get the folks who imaged the 6502 to do the same for the VIC-II, as that would dramatically reduce the time required, by revealing the remaining secrets of how the thing works.

The other strategy that I would like to apply is to rig up a C64 in a harness that allows complete control via the expansion port under DMA, and also monitors the composite output of the VIC-II, and thus provides a rapid test framework that can be iterated quickly to understand behaviour of the VIC-II under a wide variety of conditions, basically allowing reproduction of all known problematic behaviours, and iteration until we can reproduce them in the VHDL model.

I agree that all these efforts will still require a lot of time, but for the long-term preservation of the platform I think it is important.

append delete #5. gpz

multiple closed implementations of the VIC-II

there are? which would that be? chameleon - and what else? (DTV doesnt count, thats just... ugh)

append delete #6. Daniël Mantione

There is the Mist FPGA computer which has a C64 core. I don't know who wrote it and how good it is.

The 1541 Ultimate II core is open source. Because he mentions that the 1541 Ultimate and the Ultimate 64 will share source code, it would be in the line of reason that he will also open source the Ultimate 64 core.

append delete #7. Daniël Mantione

I must say more coöperation on hardware development would be very welcome for standardization purposes. For example there are now several SID re-implementations:
- SwinSID in various versions
- 1541 Ultimate
- FPGASID
- Turbo Chameleon C64 core

These devices have very nice features, such as stereo, more voices, proper PCM sounds and more.

However, for software development, the community of each of these products is too small to code software extensions. In fact, the good thing about the Commodore 64 was always that all computers are completely equal. So what do you do as coder? Just support the original SID.

Some standardization would at least increase the market you could target by supporting SID extensions, and might improve software availability.

append delete #8. gpz

There is the Mist FPGA computer which has a C64 core. I don't know who wrote it and how good it is.

the mist uses the fpga64 core, which is the predecessor of what became the chameleon core (the chameleon core is currently called "v5" internally - indicating the fifth rewrite). its pretty bad in comparison. however i asked about *closed* implementations :)

append delete #9. gpz

So what do you do as coder? Just support the original SID.

and thats what they should do (if you want stereo, support two SIDs). as for chameleon, we explicitly said that we do NOT want to create a new platform - and anything we do tries to be as close to the real thing as possible.

append delete #10. Daniël Mantione

I think that is way too simple statement in the context of the Mega65: The sole purpose of the Mega65 is to extend the platform. Its design goal is therefore different than that of the Chameleon. With any extensions, it raises the question how to get software that uses it and one answer is standardization. Even stereo SID is not standardized: $d420 or $de00. And therefore harder to support.

Personally I would love to hear what the 8 voice SID of my 1541 Ultimate II could do. But it's likely that that will never happen.

append delete #11. MIRKOSOFT

Like I see, again and again C64 users looking at Mega 65 as Commodore 64-IV... No! Can any C64 user forgot that 64 is best computer? Look at C128 and what happened for C64 compatibility - really we need not the same, even any Chameleon-II or Ultimate-3.
C64 is not best computer, it's best selling computer.
Hate me if you want - that's truth
Miro

append delete #12. gpz

I think that is way too simple statement in the context of the Mega65

yes it is. mega65 is a different platforms and as a coder you should write programs for this platform (i have my doubts that this will ever happen, but thats another story)

this thread however is about "Another c64-ish motherboard in development" - something the mega65 is not. gideons board is a c64. chameleon is a c64. c64reloaded mk3 is a c64.

#13. Daniël Mantione

This post was deleted by its owner

append delete #14. Daniël Mantione

Let's keep the subject on the SID: The 1541U2 provides two 8 channel SIDs and 8 PCM channels, on classic hardware. The Ultimate 64 includes the 1541U2, so it will likely have 8 channel SIDs as well. It clearly extends the platform.

Just because the Ultimate 64 is a C64 and the Mega65 is an enhanced C65, is that sufficient reason to say there should be absolutely no attempt to try to achieve some kind of compatibility between sound playback on both boards?

The Mega65 has HDMI and VGA. One of its Vic4 extensions is that it has registers to tune some aspects of the HDMI/VGA output. The Ultimate64 has HDMI. Should Gideon refrain himsef from implementing registers to tune the HDMI picture, just because he is developing a C64 board?

append delete #15. gpz

The 1541U2 provides two 8 channel SIDs and 8 PCM channels

it provides two SIDs, regular 3 channels each. the PCM stuff is an extension indeed.

Just because the Ultimate 64 is a C64 and the Mega65 is an enhanced C65, is that sufficient reason to say there should be absolutely no attempt to try to achieve some kind of compatibility between sound playback on both boards?

comparing the c65 mode with c64 emulators is simply pointless, those are two totally different - and very likely incompatible, things. if the MEGA65s C64 mode is aiming to be half compatible, it cant extend the platform much over what is available as regular extensions to a real C64.

Should Gideon refrain himsef from implementing registers to tune the HDMI picture, just because he is developing a C64 board?

since HDMI supports 50/60Hz pictures perfectly, i dont even see any reason why this would be necessary :)

that said, those demanding all those fancy things are not the ones who will write software for it - and those who are writing software focus on the real C64 and some of its extensions. which is good in my book :)

:: @gpz added on 19 Jul ’17 · 02:45

edit: oh i see, U2 actually has those 8 voices. in all the years of owning (3 by now) 1541U i never realized that - nor cared :) demonstrates quite well how much programmers want to use this kind of thing - not a single program exists (correct me if i am wrong)

append delete #16. Daniël Mantione

For completeness, here is the documentation of the 1541U2 SID:

https://xp-dev.com/svn/1541UltimateII/trunk/doc/sid.pdf

append delete #17. pmprog

yes it is. mega65 is a different platforms and as a coder you should write programs for this platform (i have my doubts that this will ever happen, but thats another story)

I intend to try and produce a few games, but my biggest concern is the level of documentation of the features available on the MEGA65.

Don't get me wrong, I appreciate it's all still in development, but without some decent docs and/or an easy-to-use mega65 header/library for cc65, it'll be a hard sell.

append delete #18. PGSmobile

You're welcome to help us write the documentation :)

append delete #19. pmprog

Possibly, but my VHDL understanding is rather limited, so trying to understand the source in the first place might be a problem...

If we get to a point of documentation, I don't mind trying to help make a mega65 header/library for cc65

append delete #20. gardners

If you are genuinely willing to make a library, we can provide you with information as you need it.

append delete #21. pmprog

I certainly plan to, I'm currently working on a C64 game, and am writing that in a way that most of the non-game-specific code is in a reusable manner. So expanding that library up to the MEGA65 is certainly planned

append delete #22. Daniël Mantione

Well, at least the Commodore 65 has some documentation. So could consider adding support for some Commodore 65 features. Perhaps this would also be a good test to see if the Mega65 is really compatible to the C65 as it is documented.

append delete #23. gpz

not even C65s are compatible to the C65 as it is documented :) does MEGA65 even have a "compatible to C65" mode?

append delete #24. Daniël Mantione

If it respects the philosophy behind the Commodore 65 design, it should not have a Commodore 65 mode. Just like the Commodore 65 extends the Commodore 64 hardware without special modes, the Mega65 should extend the Commodore 65 hardware without special modes.

IMO the Mega65 team can some freedoms in situations where the C65 is not compatible to its own documentation, as it attempts to create the machine that Commodore did intend to make and this is not 100% recorded history.

append delete #25. gpz

Just like the Commodore 65 extends the Commodore 64 hardware without special modes, the Mega65 should extend the Commodore 65 hardware without special modes.

um, didnt the MEGA65 implement quite a bunch of things that the C65 didnt have? and isnt the C65s C64 mode not quite compatible at all? *shrug*

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