Hi all,
I'm very new to the Atari scene and I'm currently playing around with emulating the Atari 800XL in an FPGA. I know, I know, you've heard it all before, blah blah. Well, it'll never get done if no-one makes an attempt - right?
Let me get my question out of the way first - I can't for the life of me find any reference to the frequency of FØ0 generated by the GTIA and fed into the ANTIC!?! Can anyone tell me what it is?
Back to FPGA's - I've seen a few different people announce similar projects over the years, but I don't know of anyone that has finished the job!?! Has anyone finished?
Anyway, I have the kernel ROM executing right up to the point where it loops polling the ANTIC VCOUNT register. So now it's time to start implementing the video chips. I've got my NTSC colour clock frequency, and my CPU frequency derived from that; but not sure how the ANTIC derives its 3.5MHz & 7MHz signals. I presume FØ0 is one or the other - yes?
The Atari sure is an interesting beast! I've done complete implementations of the TRS-80 (Models 1, 3 & Coco 1/2), a reasonably functional BBC Micro & Super80, and a very rudimentary Apple II. Not to mention dozens of arcade games. My project page is here. But the ANTIC & GTIA are like nothing I've come across before! I'm looking forward to the challenge!
So any help with FØ0 would be greatly appreciated!
Regards,
I'm very new to the Atari scene and I'm currently playing around with emulating the Atari 800XL in an FPGA. I know, I know, you've heard it all before, blah blah. Well, it'll never get done if no-one makes an attempt - right?
Let me get my question out of the way first - I can't for the life of me find any reference to the frequency of FØ0 generated by the GTIA and fed into the ANTIC!?! Can anyone tell me what it is?
Back to FPGA's - I've seen a few different people announce similar projects over the years, but I don't know of anyone that has finished the job!?! Has anyone finished?
Anyway, I have the kernel ROM executing right up to the point where it loops polling the ANTIC VCOUNT register. So now it's time to start implementing the video chips. I've got my NTSC colour clock frequency, and my CPU frequency derived from that; but not sure how the ANTIC derives its 3.5MHz & 7MHz signals. I presume FØ0 is one or the other - yes?
The Atari sure is an interesting beast! I've done complete implementations of the TRS-80 (Models 1, 3 & Coco 1/2), a reasonably functional BBC Micro & Super80, and a very rudimentary Apple II. Not to mention dozens of arcade games. My project page is here. But the ANTIC & GTIA are like nothing I've come across before! I'm looking forward to the challenge!
So any help with FØ0 would be greatly appreciated!
Regards,