Border effects don't work in the Emu

[MackW]

RFDV7.rom does some border effects based off the VBL on port $FD The emu doesn't seem to handle these - Aqualite does (Virt Aquarius doesnt)

[fvdhoef]

I don't have access to a real Aquarius and as such I've not been able to measure the exact frame timing. Also the emulator is only emulating line by line.

[MackW]

at a guess, - you are taking the border colour at frame start, and then not updating it through the frame (as virt aquarius does). Aqualite does a cycle count, so that it knows where it is on the border. It's the same stuff as what was done on the speccy, changing border colour mid frame gave a split. is how it should look

[MackW]

I can do the frame timings for you if it helps ?

[fvdhoef]

The border color/character is read every line rendered in the emulator. On the actual hardware it is read at the start of each border character.

[MackW]

Sean's just posted a vid that the border is behaving the same for both the emu and HW versions.

https://github.com/fvdhoef/aquarius-plus/assets/6732183/f77dcb90-d627-462d-af32-df730b0bb55c

[MackW]

Border should be Black until the top row, then red and red until 1px of the border at the bottom

[fvdhoef]

It probably then has more to do with the behaviour of port $FD. The value in there currently is: 1 for lines < 242, otherwise 0. There are 262 video lines in total. The first 240 are visible.

[MackW]

Ahh, the value on the real hardware is actually 1 between lines 0->25 char lines .. need to check the values, but $FD is still 0 until the first Char display line starts So the VBL on $FD doesn't change until it starts displaying the new Char screen, - So it's not a true VBL as such, just a "I'm doing the top/bottom border' flag

[fvdhoef]

If you can describe me the correct behaviour that would be great! Then I can fix it.

[MackW]

Let me find the stuff I gave Richard for when he did Aqualite.

[MackW]

Lol... possibly a little simplistic, but corrrect (RHS lines should match LHS lol)

[fvdhoef]

So the value is already low in the border? Top/bottom border that is. So then it isn't really a vblank, but more of an 'active area' indicator.

[MackW]

Yes, it goes low at the first line of the border at the bottom of the screen, and stays low until first line of the top drawn screen 100% - active area - you got it

[fvdhoef]

Can you give me the RFDV7.rom so I can test with that?

[MackW]

Zip file of the ROM in question for archive RFDV7.zip

[fvdhoef]

Fixed in emulator commit ee99189d5e8cc2a49688887c626fd5c486a40fcb and FPGA commit 36576eb7472c257a5f3b22f93ffcab3909fb0dee

[fvdhoef]

Thanks Mack to help with this!