Commander X16

You seem to be holding context in your head that you aren't expressing here. There are HSCROLL and VSCROLL registers, but you are using language "scroll register Y" and "scroll register X" which creates ambiguity as to whether you are using "scroll register Y" to mean ...

Wavicle wrote: ↑Thu May 15, 2025 6:45 pm I am the one who added 240P mode to VERA

Just a short reply here, I am sorry for being rude before. I'll respond to the rest later.

I am constantly coming up with new ideas to test VERA, and many of them prove that there might not be a bug.

I still don't quite understand what is is that you are saying is wrong. Scanline register in NTSC mode is not behaving like in the documentation. 240p is not interlaced. Adding +1 to the current scanline register for the next IRQ LINE interrupt shouldn't work since bit 0 is ignored, still every oth...

In the previous post I noticed those were 2 scanlines in height instead of one, so I did a chance and made register scanline + 1 for the IRQ LINE instead of register scanline + 2, and this is what I got: 240p_frame_0.jpg Yay! Except, next frame.... 240p_frame_1.jpg Ouch! So it flickers between these...

[strike]I don't think there is any bug in NTSC on real hardware[/strike]. The problem all along was that it does take a long time until the scanline has been rendered compared to VGA, but after that, there is no odd scanline but rather just the next scanline. This causes a delay to starve any remain...

Very cool! Yea might be be first with this concept, I like it! Obviously I am not 2 players. Maybe make a video when two are playing? A visual improvement suggestion: I am assuming your HUDs are 16 pixels high, and a visible playfield is 224 pixels high, and sprites are 32x32 max? If that is the cas...

I see that your ISR always acknowledges both LINE and VBLANK IRQs regardless of which one actually hit Yes, but when I did just acknowledge vblank by itself, no matter if I had set the scanline to go off at 436 (before leaving vblank isr), IRQ LINE triggered directly at scanline 481 instead (in the...

I made an experimental change... While it did move the location where the background color changes earlier, it was still in the visible area of the display. I did not expect this; it should have given... It has been known for some time that there is no time to make it to our own interrupt code, but...

I was thinking about what can be the problem with waiting too long on a scanline, and wonder if the acknowledgement of the IRQ LINE must happen before or after the NOPs? What if a new IRQ LINE is generated while still processing the interrupt, even if the scanline number was changed (doesn't make an...

Your ISR is interrupting your main code while your main code is possibly still setting up the VERA for the test, and your ISR is not expecting to need to preserve the state of the VERA's address(es) when it returns. In your main code, try moving that PLP to the end of your main code, after it finis...