Archive for June, 2010

Sprites cell configuration test rom

Posted in Uncategorized on June 11, 2010 by pcedev

screen cap

A sprite cell configuration demo. It lets you select one of 6 sprites sizes based on X/Y value and the vram offset (done in 0x20 byte increments). Select resets the demo back to the original values. Useful if you need to quickly test out valid vram offsets for certain sprite sizes.

Download here.


RCR interrupt test

Posted in Uncategorized on June 9, 2010 by pcedev

led to some interesting visual artifacts. I was testing to see where RCR interrupt starts relative to the end of HDW. In my tests demo, I was using the half sprite mode demo – which has 2 H-int’s per scanline. The idea was to use BG color #0 to get a visual cue as to where the interrupt happens. I didn’t anticipate the double h-interrupts, so you don’t see it happening across the screen. But what you do see is the artifact of the VCE stretching the last pixel displayed. Funny thing is, this happens on the last 8 pixels of HDW. The interrupt call itself is 8 cpu cycles, and there’s a PHA right before the lda <var;sta $405. So it looks like the interrupt happens somewhere about ~20+ cpu cycles before the end of HDW.

And because there was two interrupts per scanline and I didn't account for it, it allowed you to see the prepping of the VCE back to color #0 (stz $402;stz $403;stz $404). It created a new distortion to the screen, but without changing any colors. So I extended the prep parts to cause wider distortion.

You can see the results here:

Using some tricky coding and such, I can move that effect around the screen as well as make it wider and shorter, on a scanline basis. But for this video, I only widened a few different areas to make it more visible. Pretty cool effect, though IMO.

Posted in Uncategorized on June 9, 2010 by pcedev

I forwarded the domain to this blog. Take that, hackers! Mwa-hahahahahaha…..

small test demo

Posted in Uncategorized on June 8, 2010 by pcedev

Ok, here’s the 16×8 sprite test demo. It’s not much to look at (and the code is very old, from an old test source): here. The BG scrolls automatically but you can also control it with the direction pad. That’s to show that the BG is in normal, non scanline skipped mode (8×8 tiles). There’s a sprite that’s off screen that you need to move to the left. Use that to cause sprite drop out on the line of sprites on the screen (they’re 32×32 but shown as 32×16). I didn’t offset set the single moveable sprite with even or odd increments, so you can see it switching between the frames as it moves up and down (showing either even or odd row of pixels of the sprite). The moveable sprite is just there to show off the sprite bandwidth and that it’s full/normal. I really need to make a proper demo, but right now I’m doing other tests on the PCE (yay fun!).

If anyone runs this on the real system (doesn’t work yet in emulators), if you can please post back what make/model PCE/SGX you ran this on and if it does or doesn’t show as it should.

Sprite talk…

Posted in Uncategorized on June 8, 2010 by pcedev

I did some more tests. Made a test rom even for the real system (as no emulator handles this yet). I got full sprite bandwidth, but it required clipping the display on the right 3 cell (24 pixels). Not bad. Not baaaadd at all. For those unfamiliar with what I’m talking about, on the PCE if you set the display too wide – there’s not enough time during ‘hblank’ (hblank on the system side, not just the actual signal) to process and fetch all the sprite pixels for the scanline. So the VDC starts to drop two sprites at a time. I was a little worried that too much clipping would be required for all sprites to be processed on a scanline. But this wasn’t the case, thankfully.

Right now, I have HSW=2, HDS=1, HDE=4, HDW=$1C, VDW=$1E1, VDS= $1f. I still have to setup an RCR routine to see if there’s double h-sync INT calls. But if so, not a problem as you just use even numbers (zero out the last bit of the scanline number). This is pretty exciting. I need to sharpen up the demo with some fresh graphics and release it to the pce community for people to test out different systems. This should be the same on all systems since there are no ‘A’ revisions to any 6270’s that are known (only 6260’s and 6280’s). But better to be safe. For all my tests currently, have been on the original white PCE. I’ll test out on a US Duo and SGX tomorrow (well later today, but I need to sleep still).

Oh and..

Posted in Uncategorized on June 7, 2010 by pcedev

mednafen 0.9.0 WIP kicks ass. It supports a lot more VDC timing stuff – including skipping scanline, etc. Very nice. Among other features.

Posted in Uncategorized on June 7, 2010 by pcedev

Someone hacked the site :/ Suspiciously, my email on that domain still works. I no longer have access the FTP login (user/pass has been changed). Nodt, if you see this – got any ideas how to fix this? I believe your server is still setup for this domain.