1 (edited by Crispy 2018-10-26 22:24:23)

Topic: Crispy's NTSC C64 Core

Greetings one and all,

I've been corresponding with Mike in regard to various FPGA related topics over the past couple of years. During that time I had been working on a C64 core for my own FPGA hardware that I designed way back in 2011. A little over a year ago I had reached a point where I was happy with it, and decided to move on to other projects.

Well I recently got the itch to play some C64 games again, so I dusted off my C64 core, flashed my board with it, started up one of my favorite games, and right off the bat spotted a bug. Of course that wouldn't do, and just like that I found myself back in my C64 code again.

After I had found and fixed the issue I was corresponding with Mike about it, and he asked if I would be willing to check my code in to SVN. Now I seem to remember asking him a while back if he would be interested in me porting my code to work on the Replay board, but don't remember getting an answer. He reminded me, in very strong terms, that yes I did ask him, and yes he was interested! So, better late than never, here it is.

For lack of a better name, at Mike's suggestion I'm calling it Crispy's C64 core, or CC64 for short. This core models an NTSC Commodore 64. It is designed to drive modern flat panel monitors via digital DVI or HDMI. Currently it can output SMPTE 480p and 720p video. Analog DVI works, but there is no support for 15 KHz RGB or composite / S-Video. Of course it's still a work in progress, so that may change in the future.

Please direct any feedback, constructive criticism, bug reports, feature requests, etc. to the email address in the license.txt file, or post a reply here.

Update 9/10/18
I ported my PAL core over, so now CC64 does both NTSC and PAL.

Update 10/26/18
Made some improvements to the SID.

You can download it here:

Re: Crispy's NTSC C64 Core

Excellent work, looking forward to playing with it!

Re: Crispy's NTSC C64 Core

Nice, I'll definitely check this out as soon as I have a spare moment.

4 (edited by phluxx 2018-09-15 10:31:20)

Re: Crispy's NTSC C64 Core

Thanks (again?) for this core, I really appreciate having more options for c64 games wink

I just tried Katakis on your core, not the easiest candidate, I guess.

The game comes with an integrated fastloader and it is known to be unstable in terms of timing, cheat pokes etc. The original versions even erase the disk if a copy is detected.

There are 3 different official versions of this game, and a lot of cracks, including newer ones with improved emulator compatibility.

I have tried "Katakis V1 / Emulators +4" which allows to disable the fastloader.

This version runs perfectly, including fast loader, up to the point where the first boss appears. Seems that the collision detection is not working there. The boss should flash with every hit, but I can hardly make him flash once in the given time. (I checked the youtube longplay to see how it should work)

c64 core by WoS hangs/crashes at random positions , e.g. just after the main menu. I did not make it to the first level with a few attempts. Interestingly, this is independent from the fast loader setting. Fast loader seems to be working well here as well.

Then I tried another version of the game: "Katakis V2 Cyberpunx +5".
This is interesting, as it might be fixable easiliy. both cores, your cc64 and the WoS core, have the same issue: I cannot start the loader prg. After LOAD "*",8,1 and RUN, I just get a READY. First I thought its the image, but it's working well on Vice.

SDCard used is a SanDisk Ultra 80MB7s SDHC, 32GB

Re: Crispy's NTSC C64 Core

Thanks for the feedback!