exxos's Atari, Amiga & retro forum

After MMU and Blitter, now is the turn for a FPGA core running a cycle exact GLUE implementation on an H5 dev board.

I'm not going to bore you with demo pictures :) One interesting feature though, is to "simulate" different chipset versions. As most demo coders (and full screen masters) know, there are two different GLUE versions, with different top border height at 50 Hz.

FPGA core configured as the newer, and more common, GLUE version with longer 50 Hz top border:




Here configured as the older GLUE version with the shorter 50 Hz top border:

Sorry again for the picture quality. My monitor is adjusted for 60Hz. This is probably how the Atari engineers at USA checked the screen at 50Hz.

Fantastic job. I wish one day you will find time / interest to do something similar for Falcon chips (SDMA, Videl and most importantly, the rarest one, Combel), I would give my kidney for such a project! ;-)

Really awesome work.

Great @ijor

ijor wrote: 29 Oct 2024 05:08 FPGA core configured as the newer, and more common, GLUE version with longer 50 Hz top border:

I see that the screen is not centered with that common GLUE. But if I remember correctly that on my TV the Desktop was centered with 1040 STfm (new GLUE if I remember correctly).

rubber_jonnie wrote: 29 Oct 2024 09:25 Really awesome work.

+1

Once again, bravo !

:dualthumbup:

BW

Amazing!

Cyprian wrote: 29 Oct 2024 10:03 I see that the screen is not centered with that common GLUE. But if I remember correctly that on my TV the Desktop was centered with 1040 STfm (new GLUE if I remember correctly).

This is because the monitor was adjusted for 60Hz. As I said, I speculate that this is how originally the Atari engineers tested the 50Hz mode. They adjusted the "short" 50Hz border because that's how it produces a centered screen, again, when the monitor is originally adjusted for 60Hz. But if you connected to a "standard" european tv, the short border was probably too short. So Atari changed the 50 Hz border with the newer GLUE version, to better fit european monitors and TVs, I guess ...

mikro wrote: 29 Oct 2024 08:07 Fantastic job. I wish one day you will find time / interest to do something similar for Falcon chips (SDMA, Videl and most importantly, the rarest one, Combel), I would give my kidney for such a project! ;-)

This would require decapping the Falcon chipset in the first place, which I estimate it would cost about $500/$1000 USD per chip. That's just for getting high definition die images, not the actual reverse engineering. I seem to remember we talked about this already in one of the forums. Anyway, if you want to follow up, please open a separate thread.