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The default speed of the Mega65

  • The default speed is the one of the Mega65, 40 MHz. Why should it be different? As Snoopy stated: The 40 MHz has been decided long time ago. The Mega65 has a VIC-IV and 40 MHz. That's a fact. Why should it default to something less?


    So: It is a Mega65. That's why it should start in Mega65 mode (40 MHz, VIC-IV). Not in C64 mode (1 MHz, VIC-II). Not in C65 mode (3.5 MHz, VIC-III).

    As deft as one of the devolpers of the MEGA65 wrote in the quote above, the 3.5 Mhz in the MEGA65 are "useless". They are too slow for the features of the C65 and especially of the MEGA65. So there is no reason to have the 3.5 MHz at all. They are still there because of using the old original C65 ROMs, but even there the 3.5 Mhz are too slow for using all C65 features.

    That's the other thing I am talking about. 3.5 MHz is too slow to use all the features the C65 actually had. Early reviewers of the prototypes complained about it. This machine should have offered a few nice things, but couldn't show them off, since of this shortcoming. This is why the Mega65 team "finished" this development and found a solution.


    I am sure even Commodore knew of this problem and if they hadn't abandoned the project I am conviced they would have addressed this issues one way or another. Most likely not with 40 MHz, but probably some other way. Maybe with a higher clockrate in combination with a coprocessor.


    The Mega65 team has thankfully addressed it with their own take on it and we should be glad and use this computer as it was designed to. From the default state.


    40 MHz would have been quite much in the early 90s. I know. But as stated several times before, this is NOT a C65. It is the Mega65. And the 40 MHz is the native speed it was build for.


    Those of you who are pleading for 3.5 MHz as default are suggesting to slow this computer down to some unfinished prototypes which had severe and then unaddressed issues showing off the actually built in features.


    And you can see it from this side as well: The CMD SuperCPU ran at 20 MHz with a 16 Bit CPU and up to 16 MB of RAM. It was introduced in the mid 90s. So 40 MHz are not that far fetched.

  • The CMD SuperCPU ran at 20 MHz with a 16 Bit CPU and up to 16 MB of RAM. It was introduced in the mid 90s. So 40 MHz are not that far fetched.

    Not far fetched? Well you have to take into account the speed of technical progress here. The mid 90s already had Doom (1993) and Quake (1996). But the C65 was designed in the late 80s. The Super NES came out around 1991 and had a 3.5 MHz 16 bit CPU.


    It might be true that the 3.5 MHz 8 bit CPU was simply too slow for what the C65 would have had to offer, I get that. But on the other hand, I wonder why the gap between 3.5 and 40 has to be that huge. Would the C65 have been usable if it had 7 MHz for example? What kind of games would have been possible on such a machine? 40 MHz seems to be already quite a lot compared to the original 3.5 MHz.


    Still I think there's nothing wrong to use the 40 MHz mode, it is there for a reason. On the other hand, making this the default mode will make the 3.5 MHz mode completely meaningless and almost useless. Why should anyone switch back to that? Whereas if it was the default, it would be a more conscious decision whether to code a game for the default mode or the turbo mode.


    Of course I haven't worked thoroughly with the MEGA65 yet and I can't really judge how bad the 3.5 MHz mode is. Maybe it's really that bad. But e.g. a game like "Wave Hero 65" looks like it could be possible in 3.5 MHz mode (I don't know what it really uses, so you might correct me here), and it would be cool to see a few more "C65-baseline" games in the future. But this would be more encouraged if that was the default mode and the other would be considered "turbo".

  • [...]

    And you can see it from this side as well: The CMD SuperCPU ran at 20 MHz with a 16 Bit CPU and up to 16 MB of RAM. It was introduced in the mid 90s. So 40 MHz are not that far fetched.

    Although it intrigues me why they overclocked the 65816 up to 20 MHz. Even the 16 MHz 'native' Mode of the 65816 would have been a huge enhancement.

  • Not far fetched? Well you have to take into account the speed of technical progress here. The mid 90s already had Doom (1993) and Quake (1996). But the C65 was designed in the late 80s. The Super NES came out around 1991 and had a 3.5 MHz 16 bit CPU.

    As you know the C65 was not finished in den late 80s. It was abadonend. Had Commodore finished it it would have probably been delayed to the early 90s to sort out the hardware and software issues. And then we are not that far away from the 20 MHz SuperCPU. That's what I meant.


    I get that you want as close an experience to the C65 as possible. My point is that Commodore hadn't finished the design yet and that you are talking about mimicking a machine which flaws hadn't been addressed so far.

  • My point is that Commodore hadn't finished the design yet and that you are talking about mimicking a machine which flaws hadn't been addressed so far.

    Yes. IMO thats the main point here. The C65 was a prototype and those are prone to be changed. So the main question is, how close to be production ready was the C65 actually?

    To me the MEGA65 is the "8-bit fantasy" machine, that provides the feeling of direct control, that was a major point of computing at that time, while still having more modern features to be actually nice to use in todays time. Like a remaster/remake of a game, where it is important to keep the spirit of the game, bit not the problems which are hidden by nostalgia, so that when you play that game it transports the feeling as you remember it and not as it actually was. :)

  • Yes but the SuperCPU was introduced in 1996, that was when we had Quake. The C65 was abandoned in 1991, that's when we had Wolfenstein 3D. These are 5 years of time and a lot happened in between. And 40 MHz is still double the frequency of the SuperCPU btw. So I don't think that analogy is very realistic ;)


    But yes I understand that the 3.5 MHz might have been underpowered for the C65. Maybe that's why they ditched the project in the end. However, since the C65 is considered to be a successor of the C64, I'd rather have it a bit more similar to the C64 indeed, as opposed to something that beats the Amiga.

  • I guess it comes down to different schools of thought. Do you consider the MEGA65 a recreation of the C65? Or a new 8-bit-computer in 2021 that's based on and compatible to the C65? The answer directly influences the boot-clock-speed-preference I guess.


    Speaking of preferences: Is there a user setting for the boot-clockspeed? Maybe that's the solution. Still, make 40 MHz the default please :-P

  • But yes I understand that the 3.5 MHz might have been underpowered for the C65. Maybe that's why they ditched the project in the end. However, since the C65 is considered to be a successor of the C64, I'd rather have it a bit more similar to the C64 indeed, as opposed to something that beats the Amiga.

    The C64 beats the Amiga hands down by definition anyway. :thumbsup:

  • I guess it comes down to different schools of thought. Do you consider the MEGA65 a recreation of the C65? Or a new 8-bit-computer in 2021 that's based on and compatible to the C65? The answer directly influences the boot-clock-speed-preference I guess.

    Yes indeed. And for my perspective, the MEGA65 is the "completion of the C65", as has been said quite often. Yes, it has some new features, but still, I mostly consider it to be the "bringing to market" of a finished C65 in modern times, not so much a "new 8bit fantasy computer that looks like a C65 and shares some similarities" :)


    Speaking of preferences: Is there a user setting for the boot-clockspeed? Maybe that's the solution.

    No, that is not the solution, as I explained a bit earlier. Of course everyone is able to set it by himself, either in the BIOS, or as an autorun program. That's not the issue. However, declaring something as the DEFAULT has a strong impact, as I tried to explain numerous times. Think of the McDonald's menus, they sell much more "maxi" menus these days than before, because they made "maxi" the default and renamed the former default "small" now. Everyone who's just ordering a menu, will by default order the "maxi" version, even though still everyone has the choice.

  • Please guys, but what are those C65 features for which you think the 3.5 MHz is not enough? That's already more than four times faster than the C64's. Whereas the typical screen resolution is only the double (640x200) and you even have a built-in DMA (which is a game-changer in itself).


    As far as I can see, the weakest point of the C65 hardware is rather the 128K RAM. However a +512K RAM expansion was about to produce, too.


    The only single feature discussed in this topic is the default speed at powerup. While everything, and everything else is accessible for the applications at any time, of course.

  • Please guys, but what are those C65 features for which you think the 3.5 MHz is not enough? That's already more than four times faster than the C64's. Whereas the typical screen resolution is only the double (640x200) and you even have a built-in DMA (which is a game-changer in itself).

    Bitplanes. The Amiga has it. But the Amiga has also Blitter and Copper. The C65 however is too slow to effectively use bitplanes. The Mega65 corrects that:


    Mega65 talk at YouTube (Bitplanes starts at 14:20)

    https://c65gs.blogspot.com/2015/10/ (look at the entry on Oct 16, 2015).

    The Mega65 team has stated several times, that the C65 was actually too slow to show off built in features. Their take on it was to increase the clockspeed, to "repair" this issue.


    We are talking about defaulting to the broken and unfinished state the C65 was in knowing that this is not the C65 but the Mega65 which was built with another clockspeed in mind.

  • But Paul has always said that the Bitplane modes are basically useless, and that's why he invented the VIC-IV with Raster Rewrite Buffer.

    So the fix for the Bitplane modes is the VIC-IV, not the 40MHz, and as far as I can tell, the VIC-IV seems more realistic for the period than a 40MHz processor.

  • But why does the operating system need bitplanes for the powerup?