Making a C64/C65 compatible computer in an FPGA

[Melon]

This is something I've been keeping an eye on for a few month's now. A C64/C65 FPGA Blog.

[gardners]

If anyone is interested in helping with the C65GS (the FGPA based C65), whether testing, documentation, VHDL or writing 6502/4502 utilities for it, drop me a line.

[penfold42]

Is the http://papilio.cc/ big enough ?

How many gates are you using ?

[gardners]

Is the http://papilio.cc/ big enough ?

How many gates are you using ?

I am using too many gates right now. I need to do some significant simplifying of the CPU to fix this, which is possible without losing speed or features, as I think a lot of the problem is the Xilinx tools being a bit dumb and my VHDL being a bit non-idiomatic. The result is that, right now, I am using 89% of slices, when I think it should be more like 50% or less given the complexity of my design.

Paul.

[satpro]

I love the 65CE02 instruction set and the way it works in general! Do you have any C65 documentation to share? We were never fortunate enough in the US to have one.

[Shaun_B]

This looks quite awesome... good work! I think FPGA is the way to go in preserving old hardware. I'd love a C128 FPGA one day (unless there's one out there already that I've missed...?). If I had the time and skills, that's something that I would look into implementing. I think a lack of maths will let me down.

Regards,

Shaun.

[satpro]

If I had the time and skills, that's something that I would look into implementing. I think a lack of maths will let me down.

Nah, have a little confidence. Electronic engineering knowledge might come in handy, though.

[iced_nine]

Sweet. Anxious for the final result...

Nah, have a little confidence. Electronic engineering knowledge might come in handy, though.

Please, I', afraid to install JiffyDOS in fear of breaking something... I was brave enough to open my A500 and replace the floppy drive. Modern PCs I can tear down and rebuild blindfolded, but when it comes to the vintage ones, I tend to run in fear when opening the case and such...

[gardners]

Is the http://papilio.cc/ big enough ?

How many gates are you using ?

It would need to be a 7-series Xilinx FPGA, as I am using a lot of block RAM, and the higher speed of the FPGA.

I am in the middle of redesigning the CPU and VIC-IV character fetch to reduce the size of the design, because it was taking 94% of the quite large FPGA. It is sitting around 31% now with the redesign mostly done, but I still have to implement sprites. I also intend to put a cycle exact 6510 + VIC-II in the corner for C64 compatibility mode, and also a 6502 for 1541 emulation.

Paul.

[gardners]

An update on progress:

You can now use the C65GS prototype remotely by VNC!
(provided I have it turned on)

What is even more fun is many people can connect and watch or interact at the same time. Think of it as Twitch for commodore 64

Real-time internet streaming of 1200p video from an 8-bit computer is a fairly new art, so apologies for the video glitches and artifacts, but it is quite usable if the screen isn't scrolling horizontal too much.

For details of how to connect see:

http://c65gs.blogspot.com/2014/09/remot ... ardly.html

From C64 mode you can use SYS49152 to select from a variety of D81 disk images containing a random selection of stuff, including Turbo Assembler, a little intro I wrote for the C65 back in 1994, SynthMark64, Game of Life among others.

You can also talk to the serial debug interface, which can help debug why some software doesn't work.

If you are really keen, you can help find bugs and improve the existing C65GS firmware, including the KickStart ROM and disk chooser (which could REALLY do with having a menu).

Anyway, have fun exploring.