Search found 7 matches

by blargg
Fri Mar 12, 2010 8:28 pm
Forum: Regen
Topic: FM Timer B bug + VDP vertical scrolling bug
Replies: 6
Views: 4956

Re: FM Timer B bug + VDP vertical scrolling bug

After some investigation, I figured the problem came from Timer B counter not being loaded properly, in my case because I was doing this to detect Timer B LOAD bit changes (FM register 0x27): if ((v&2) & !(ym2612.OPN.ST.mode&2)) ym2612.OPN.ST.TBC = ym2612.OPN.ST.TBL; I'm surprised your compiler did...
by blargg
Tue Feb 23, 2010 2:26 pm
Forum: Video Display Processor
Topic: Color counts per screen
Replies: 137
Views: 28608

BTW, I play with your NTSC filter on my RPTV at all times. Would you consider a comparison between raw emulator output color counts, the NTSC filter's, and Composite useful in any way? Maybe for the NES one. The SNES one reduces to 13-bit RGB before filtering. The Genesis one isn't very accurate, s...
by blargg
Tue Feb 23, 2010 5:43 am
Forum: Video Display Processor
Topic: Color counts per screen
Replies: 137
Views: 28608

One thing is that the Genesis pixel rate is slightly less than twice the color carrier frequency, so the color fringes do a rainbow as you go horizontally across the screen. For example, a simple black and white alternative vertical pattern will generate a rainbow. On the other hand, the SNES pixel ...
by blargg
Mon Feb 22, 2010 11:21 pm
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 834
Views: 321169

Well, shouldn't we just apply a limit like it was done in the original core ? By doing this, you are reducing FM output level (relative to PSG)... I think it's not very common that all channels are set to max, hence why a limiter was used but I wonder which solution is best. It's definitely rare, o...
by blargg
Mon Feb 22, 2010 10:52 am
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 834
Views: 321169

yeah, it seems I can't download them :wink: OK, try this mirror: genesis_recordings.zip Yeah. I just modified the channel muting mask from ~0 to ~((1 << 7) - 1). This preserves the sign bit. This was in the MAME version, where it applies this mask to each channel, sums them, divides by 2, then outp...
by blargg
Sat Feb 20, 2010 8:53 pm
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 834
Views: 321169

Here are some recordings (sorry for mp3, as I lack FLAC or anything modern): genesis_recordings.zip (2.6 MB; let me know if you have problems, as this host sucks) These are from the original Sega Genesis model, not a later one where sound is really crappy (on those, getting rings in Sonic for exampl...
by blargg
Sat Feb 20, 2010 6:39 am
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 834
Views: 321169

I was doing some testing today on a YM2612 emulator of the number of bits in the DAC. I believe it's a 7- or 8-bit DAC, that's time-division multiplexed (as the YM2612 Wikipedia page says). This means that the DAC really operates at 6 times the normal rate, or 1/24 the clock input. So for the Sega G...