Search found 152 matches

by LocalH
Sat Nov 18, 2017 4:44 pm
Forum: Megadrive/Genesis
Topic: DMA transfer to CRAM visible however the screen is off.
Replies: 22
Views: 2616

Re: DMA transfer to CRAM visible however the screen is off.

There's a ROM release over at gamehut.com if anyone wants to inspect their technique and compare it to the modern one.
by LocalH
Thu Oct 12, 2017 7:08 am
Forum: Megadrive/Genesis
Topic: DMA transfer to CRAM visible however the screen is off.
Replies: 22
Views: 2616

Re: DMA transfer to CRAM visible however the screen is off.

Bumping to make sure everyone knows that apparently, Traveller's Tales almost had direct color DMA in 1993, they just couldn't figure out how to sync to the VDP. Check this video.
by LocalH
Wed Dec 09, 2015 8:55 am
Forum: Megadrive/Genesis
Topic: DMA transfer to CRAM visible however the screen is off.
Replies: 22
Views: 2616

Re: DMA transfer to CRAM visible however the screen is off.

It's my understanding that it is, as long as the additional RAM is wired up properly. Here's a thread about it.
by LocalH
Wed Dec 09, 2015 8:22 am
Forum: Megadrive/Genesis
Topic: DMA transfer to CRAM visible however the screen is off.
Replies: 22
Views: 2616

Re: DMA transfer to CRAM visible however the screen is off.

Concerning the first: wouldn't it produce a lot of flickering? Concerning the second: the architecture just doesn't allow it. Just impossible. Of course it would be good but if we would like just to dream about something then it's more reasonable to dream about some kind of modern GPU support for e...
by LocalH
Wed Dec 09, 2015 7:47 am
Forum: Megadrive/Genesis
Topic: DMA transfer to CRAM visible however the screen is off.
Replies: 22
Views: 2616

Re: DMA transfer to CRAM visible however the screen is off.

Direct color DMA is a clever hack (discovered by Oerg866 IIRC) that effectively gives you a low-res bitmap mode by abusing DMA to CRAM. The DMA engine can copy one word to CRAM for every 2 pixels (except for during VRAM refresh, which is why you see some weird doubling). So if you sync the 68K to t...
by LocalH
Tue Dec 08, 2015 5:26 pm
Forum: Megadrive/Genesis
Topic: DMA transfer to CRAM visible however the screen is off.
Replies: 22
Views: 2616

Re: DMA transfer to CRAM visible however the screen is off.

I have yet to find an image that looks better with direct color DMA than with 8 static colors + 8 colors replaced per scanline. I mean, it's easy enough to generate such an image I suppose, but if you just take a random photograph, the resolution loss looks way worse than the color loss. The best t...
by LocalH
Mon Dec 07, 2015 2:08 am
Forum: Megadrive/Genesis
Topic: DMA transfer to CRAM visible however the screen is off.
Replies: 22
Views: 2616

Re: DMA transfer to CRAM visible however the screen is off.

A possible idea I had one time (but never implemented) was to "overlap" color changes. What I mean is, group together each set of two scanlines, and change half the colors per line (8 per line should be fairly easy from what I understand, although I'm a little rusty and my knoledge is a bit outdated...
by LocalH
Mon Dec 15, 2014 11:17 pm
Forum: Exodus
Topic: Simplified release of Exodus 1.1 coming soon
Replies: 34
Views: 6142

Merry Christmas to you too, Nemesis. I await the 1.1 release, even if my computer may not be able to run it at full speed. On an unrelated note, it'd be nice to have a good debugging emulator for iOS. I have successfully compiled an iOS 7.1 64-bit binary for both asl (or "the macro assembler AS) and...
by LocalH
Tue Dec 02, 2014 6:55 am
Forum: Tools
Topic: Linux Genesis Dev Setup
Replies: 125
Views: 23586

I'm interested in exploring whether this toolchain can be ported to jailbroken iOS - I already have several non-standard (in iOS land) tools installed (gcc, etc) but I'm not sure if I have the full complement. I would love to be able to take my iPad around and code for the Genesis when I have some d...
by LocalH
Wed Nov 26, 2014 5:05 pm
Forum: Announcement
Topic: Don't forget what SpritesMind is
Replies: 17
Views: 3804

Kaneda, what you have here is simply the English-language hub for MD development (only other forum I know of that even comes close to having the technical MD knowledge that we collectively have is Sonic Retro, but their focus is necessarily the Sonic games while ours is more general). I remember whe...
by LocalH
Fri Aug 29, 2014 3:42 am
Forum: Demos
Topic: Rom dumping over audio
Replies: 5
Views: 1560

Would there be any way for this system to access each individual chip inside the cartridge (when appliable), for individual dumps? No, I don't think so. You can only see what the 68000k gets when reading from a certain address. I guess one could have a semi-automated way to do it post-dump with a s...
by LocalH
Wed Mar 12, 2014 8:12 am
Forum: Exodus
Topic: Removable test or visual artifact?
Replies: 4
Views: 1774

Those are bus conflicts resulting from writing to CRAM midframe. They're unavoidable on hardware, and also why commercial games generally wait until VInt to write to CRAM (or if they do write to CRAM mid-frame, they either limit the amount of data they write, or attempt to make the shitpixels less n...
by LocalH
Fri Feb 28, 2014 4:38 am
Forum: Demos
Topic: Ocean Melody
Replies: 6
Views: 2754

Edit: I have no idea why Chrome on my iPad is double posting, I disabled the "Reduce Data Usage" option that i thought was causing it. Delete or ignore this post pls.
by LocalH
Fri Feb 28, 2014 4:38 am
Forum: Demos
Topic: Ocean Melody
Replies: 6
Views: 2754

I can unfortunately test only 2MB ROMs with my SMD setup. I do have a non-TMSS Genesis 1 with EXT port, but I don't know exactly which revision it is. Only option I have would be to chop the ROM at 2MB and I'd rather not do so if I'm recording it. That does mean I can record the second ROM you linke...
by LocalH
Sat Feb 15, 2014 7:49 pm
Forum: Sound
Topic: z80 clocks
Replies: 32
Views: 6206

Speaking from NTSC land here. The half-line causes the TV's raster to "fill in the spaces" between the lines of the first field with those of the second field, generating a 525-line interlaced display. Literally the only difference between 240p and 480i is that half-line. Technically, in 240p, you s...