Nice find, even if the first part in this discussion is about the HELP key
and the second part goes for and back around Vaporware or not.
But it's nice to see, that Paul and Shallan already answered there.
I think that Paul is everywhere on the net if someone mention "MEGA65"!
There are a few people "around" on the net where I have the suspicion that they exist multiple times. Paul is one of these People.
In the "Tokyo Retro Computer Users" meeting on May 15, 2021, a DevKit was present along with many other older computers.Quote
Greg brought along his Mega-65, the re-imagination of the Commodore 65 by some hardcore enthusiasts. The Mega-65 was having some graphical issues but it was at least running well enough to allow us to watch 3 Stooges.
In the Finnish retro magazin "Skrolli" issue 2021.1 you can find at page 56 a review of the MEGA65 DevKit.Quote
- MEGA65 DevKit (Commodore 65:n uudet vaatteet) (s. 56)
Because it's a current issue and you still can buy it, there's only a very little thumbnail picture of the review on the net.
Maybe a Finnish fan has this issue and can read this review?
In the epsiode 273 (Published on April 30, 2021) of "The Retro Hour" you can listen 95 minutes to a audio stream about the Commodore 65 and MEGA65. You can also download the episode as a MP3 file on this site:Quote
The Commodore 65 was a cancelled super 8-bit computer from the early 90s, but in 2021 a team of hardcore fans have created a 21st century realisation of it. Running 40x faster than a C64 with some stunning modern features. We chat to project founder Paul Gardner-Stephen.
This 4 weeks old thread in "Hacker News" started with a hint to the C256 but after a few comments there is also a branch with some posts about the programming of the MEGA65:
...Quote from hth313
I looked at the Mega65 with its three (not quite) 6502 CPU variants and I just found it so weird. Basically no 16 bit operations, instead a couple of 32 bit operations. Z register is no longer 0 and you have to set it non-zero to change bank configuration. Five instructions (nine bytes) to change bank and I do not understand how you can save the previous bank setting in case you want to restore it.
If you move the stack or zero page, the well known trick of using absolute plus index register no longer works the same as on the 6502 (breaking existing code). Sure, you could hardcode a different page, but the point of moving the stack is (probably) so you could do multi-tasking. But if processes are given different stack pages, they can no longer share code (if using such well known tricks in the code). Moving zero page is in 256 steps, so you cannot use it as a movable stack frame (the 65816 can set it to any location in the first 64K).
I know there is a lot of interest in the Mega65, but I found it had so many poorly made design decisions that made me want to stay far away.
So far I find the 65816 to a well designed 16 bits ISA (I am also familiar with PDP-11, MSP430, MELPS7700 and Motorola 6812) that gives a lot of 6502 vibes, but is just a lot better. There are a couple of odd corners, probably due to the opcode space as you mention, but I would not call it a bunch of compromises.Quote from cmrdporcupine
To be clear, the value (to me) of the MEGA65 is not that its CPU is superior. It's that the developers of the project are spending a lot of time on the hard part: cases, keyboards, software, and tooling.
They have GEOS running on it, they have backwards compat with the C64, they have games modified to use its extra capabilities, they have injected molded plastic cases, they have keyboards and keycaps manufactured, they have a version of the Kernal and BASIC ported and expanded, they have a user manual, etc.
And it's a) open source and b) open.
And b) is key because they're also making it possible for their hardware to be used with other FPGA bitstreams, including ones developed for the MiST/MiSTer. They demoed their hardware being used with a GBA core running a GBA game.
Further, they seem to have a CC65 backend -- I don't know of what quality -- but it seems C based software is running on it.
That makes it an interesting and more complete platform and consumer product.
And if I want a better 6502 variant on it, I could do that myself and use one of the various 65xx variant cores out there, or write my own.
EDIT: And, yeah, from my perspective from just casually reading their docs is that the CPU in the MEGA65 is an 8-bit CPU with bank switching and a couple weird 32-bit ops. It's not a 16-bit machine despite.
But the thing about the 816 is that it's only _sort of_ a machine with a 24-bit address bus. It effectively just has a bank switching mechanism, but not external. Mensch really just bolted some stuff onto the front of the 65C02 and widened the accumulator and registers by 8 bits. But the 16-bit registers are a pain. I just wish he'd added some new registers (and a way of combining them) instead of having the mode switch.