Recreate a C64 clone with SPI screen

[Chromatix]

In the case of the SID itself, you can get very close to perfect by emulating the analogue filters with digital ones. That's how all the C64 emulators out there work. There was enough variation between different SIDs, even of the same model number, that it's very hard to "improve" it further. So you could quite justifiably bake one of those digital emulations into a microcontroller or FPGA, attach an external DAC if necessary, and make it into a drop-in SID replacement.

Everything else the C64 needs is digital, so theoretically much easier to replace with identical functionality.

[rupy]

Did you guys see these:

https://www.c256foenix.com
http://mega65.org

Also since the 65816 has successfully replaced the 6510 I'm thinking a board that can fit the VIC and SID with a 65816 and then some sort of SPI screen interface for the VIC.

Next step would be to add some proper GPU that can handle 3D graphics.

Then you have a pretty decent computer if you increase the clock.

Also you would need some keyboard and mouse interface, I'm not a fan of USB so probably I2C, I need to figure out how the CIA works.

Finally a built in Ethernet is really important, I'm thinking the same chip as the RR-Net.

Thanks for all the links, will go through them.

[White Flame]

rupy wrote:

I want to understand the VIC enough to build my own GPU that does not have the legacy of PAL/NTSC but instead uses SPI directly, the first step in this direction is to build a VIC that uses SPI to a small IPS LED screen.

SPI-connected screens don't usually run a video stream through them, do they? I think they tend to send individual drawing commands, and the display has a framebuffer & command processor built in. That wouldn't make a lot of sense in this application.

[rupy]

You are right that they require some CPU so something would be needed between the 65C02/65816 and the screen if you want all cycles for your program. But these CPUs don't even have a SPI pipe so you'll need something anyway, specially if you want the VIC to output to it. I'm a complete noob and it would be great if someone with more "GPU" knowledge would join the 6502 forum so we can get more than ASCII going for graphics!

I mean the two unique drivers for the success of the 64 was the VIC and SID chips!

Also if you look at the Mega65 project they will use a 4510 CPU:

https://en.wikipedia.org/wiki/CSG_65CE02

Anyone have any experience with those here?

[Dr Jefyll]

rupy wrote:

Anyone have any experience with those here?

Garth and I each have a couple of 65CE02 samples but haven't really done anything with them. Anybody else?

It's a very interesting chip, though. I suggest you use the forum's search facility. BTW it seems the CE02's subtract instruction is busted with regard to BCD mode -- see this post.

-- Jeff

[GARTHWILSON]

rupy wrote:

I'm a complete noob and it would be great if someone with more "GPU" knowledge would join the 6502 forum so we can get more than ASCII going for graphics!

There are a few who are not as active. One who comes to mind is "Radical Brad," forum name Oneironaut. See his YouTube channel for demo videos: https://www.youtube.com/user/LucidScience/videos . His most active topic here is the 43-page "Vulcan-74 - A 6502 Powered Retro MegaProject." Another is ElEctric_EyE. His most active topic here is the 41-page "Concept & Design of 3.3V Parallel 16-bit VGA Boards." Jeff Laughton (forum name Dr Jefyll, who has the last post above) and others know a lot more about it than I, but these are the top ones who come to mind at the moment. I'm sure I could give you more if I had been paying more attention to video & graphics.

[ElEctric_EyE]

You might just be better off buying a 6567 if you really want to build a c-64 clone, especially if you're a beginner at electronics. They sell them on eBay. But even that IC is pretty complicated. Might be worth looking into a 6845/6545 or something to get your feet wet first? I've done an old video project around the 5037 (similar to the 6845) and 8002 character generator. It was very rewarding when it finally worked but it took a great deal of effort and time! Also, no internet back then so that's in your favor...

I used wire-wrap so I could undo and redo any necessary wiring. Breadboarding is another option but for video might be sketchy because of the noise issue. However, like Garth mentioned, Radical Brad did amazing things with breadboards! You should really check out his thread... You have to start simple and build up or you will be tackling an impossible learning curve.

BTW, you've mentioned a few projects. Allow me to introduce one that I've followed on and off through the years: FPGAArcade

[cbmeeks]

rupy wrote:

Also since the 65816 has successfully replaced the 6510 I'm thinking a board that can fit the VIC and SID with a 65816 and then some sort of SPI screen interface for the VIC.

Next step would be to add some proper GPU that can handle 3D graphics.

Then you have a pretty decent computer if you increase the clock.

Also you would need some keyboard and mouse interface, I'm not a fan of USB so probably I2C, I need to figure out how the CIA works.

Finally a built in Ethernet is really important, I'm thinking the same chip as the RR-Net.

What you're describing sounds more like a modern computer running a C64 emulator. You're closer to Raspberry Pi land.

I just think the more modern devices people put on vintage computers the less it remains vintage. Like putting an air conditioner and anti-lock brakes on a Model T.

[rupy]

Thanks for the youtube link, I have no clue what I'm looking at though.

The whole point is to build a computer with newly produced components (WDC) and modern IO (I2C, SPI and ETH) _but_ with old 8-bit graphics and sound; to avoid complexity, licensing issues and costs.

The main goal is to go back and learn how computers really work, the Raspberry is not interesting in that regard, neither is Python or Javascript.

The only way forward is to go back and reinvent the wheel.

Ultimately I would really like to have a 8-bit machine with OpenGL!

[ElEctric_EyE]

It's great to dream big!

[BigEd]

Yes, go for it. A mix of vintage and modern could be rather good.

[cbmeeks]

ElEctric_EyE wrote:

Breadboarding is another option but for video might be sketchy because of the noise issue.

I've created B/W video using a PIC mcu years ago and got a really stable display. Of course, B/W is pretty simple (NTSC). I managed to get color using some multiplexers on the breadboard and it was also stable. I think a good layout will yield decent video from breadboards. But it will have noise. I didn't mind so much as I was focusing on the logic and could tolerate a little noise.

But if you *really* want a simple video solution, using new parts (only 3..mcu, eeprom and clock), then look at the Propeller. It can do VGA, NTSC, PAL, sprites, etc. All with software drivers.

It's 3V3 only but that can be dealt with. Especially for a simple computer.

[rupy]

This one?

https://www.parallax.com/product/p8x32a-d40

[cbmeeks]

rupy wrote:

This one?

https://www.parallax.com/product/p8x32a-d40

Yes. There are literally dozens of video drivers for it and the forums are very useful. The people who use it are very passionate about it as well.

https://forums.parallax.com

[rupy]

Thanks so much!

Edit: so I'm looking at static RAM, is the cypress 512K the largest one you can get?

Also a friend uses this I2C circuit as keyboard interface: http://www.ti.com/lit/ds/symlink/tca8418.pdf

But I wonder if there is a more complex one that could do even more peripherals.

Found this: https://www.tindie.com/products/jac_gou ... -computer/

But no color with the L-Star and no Ethernet... I would like to use the same chip as on the RR-Net.