Search found 3263 matches

by Zepper
Tue Jun 01, 2021 6:23 am
Forum: NESemdev
Topic: Cheap Highpass Filter? (just add/subtract and bitshifts)
Replies: 7
Views: 1117

Re: Cheap Highpass Filter? (just add/subtract and bitshifts)

I remember reading about a really cheap Highpass/DC cancellation filter that used only addition/subtraction and bit shifts. But I can't remember what the formula was, or where I heard about it from. I think emulators used this formula. Does anyone know it? You're welcome. http://forums.nesdev.com/v...
by Zepper
Mon May 31, 2021 4:31 am
Forum: NESemdev
Topic: RockNES 5.80 -May 31st 2021-
Replies: 0
Views: 880

RockNES 5.80 -May 31st 2021-

DOWNLOAD: https://www.dropbox.com/s/q6ympgtrscwsbjv/rnes570c.zip?dl=1 What's new for version 5.80 (05/31/2021) ----------------------------------------- [savestate] - The savestate version has been changed to 8, so older states are no more compatible. - Added/fixed proper savestate support for ALL m...
by Zepper
Fri May 28, 2021 8:36 am
Forum: NESemdev
Topic: mapper 97?
Replies: 4
Views: 807

mapper 97?

The wiki brings the following info: $8000-BFFF: [M..P PPPP] P = PRG Reg (16k @ $C000) M = Mirroring: %0 = Horz (PPU A11) %1 = Vert (PPU A10) Disch' mapper 97 document brings a bit different: $8000-FFFF: [MM.. PPPP] P = PRG Reg (16k @ $C000) M = Mirroring: %00 = 1ScA %01 = Horz %10 = Vert %11 = 1ScB ...
by Zepper
Thu May 27, 2021 7:58 am
Forum: NESemdev
Topic: Namco 163 output examples
Replies: 0
Views: 1099

Namco 163 output examples

3 recordings from my emulator (WAV format).
"Toad Man" (GBS2NSF conversion).
"Sangokushi 2 - Haou no Tairiku"
"Final Lap"
https://www.dropbox.com/s/mgk1eox62dn4j ... c.zip?dl=1
by Zepper
Wed May 26, 2021 6:45 pm
Forum: NESemdev
Topic: Namco 163 audio?
Replies: 16
Views: 3668

Re: Namco 163 audio?

I've found the problem.
I messed up the RAM pointers. :oops:
Now it's playing OK.
by Zepper
Tue May 25, 2021 1:45 pm
Forum: NESemdev
Topic: Namco 163 audio?
Replies: 16
Views: 3668

Re: Namco 163 audio?

lidnariq wrote:
Tue May 25, 2021 1:44 pm
That sure looks like you found a bug/design flaw in the game. It should generate the whine at 7.5kHz that you hear.
The same occurs with Erika to Satoru no Yume Bouken.
Plus, the wiki says (NSF page) that it uses registers $4800 and $F800. What about register $E000:$40? Is it unused?
by Zepper
Tue May 25, 2021 1:19 pm
Forum: NESemdev
Topic: Namco 163 audio?
Replies: 16
Views: 3668

Re: Namco 163 audio?

Well, after two days of work (and a big thank you for Mesen' source), I could get it working... except for an annoyance I can't figure out. Channel 8 (the first one) outputs a high frequency sound when it should be in silence. Here's a LOG of the channels. I'm using the game Final Lap (J) for testin...
by Zepper
Mon May 24, 2021 7:45 am
Forum: NESemdev
Topic: Clock is skipped too late, relative to enabling BG
Replies: 3
Views: 1494

Re: Clock is skipped too late, relative to enabling BG

In my emulator, the extra cycle occurs at PPU cycle 337 (pre-rendered scanline) if it's an odd frame and background is enabled. You increment the PPU cycle counter at PPU cycle 337.

[odd frame] (337 + 1) + 3 (next clock) = 341 (takes 1 CPU cycle).
by Zepper
Fri May 21, 2021 12:16 pm
Forum: NESemdev
Topic: Namco 163 audio?
Replies: 16
Views: 3668

Re: Namco 163 audio?

One last question.
It says... "The output will be held until the next channel update. The 24-bit phase value will be stored back into w[$7D/$7B/$79]"

So, at every CPU cycle, each channel returns the last generated output sample. It holds the sample until the next update (+15 cycles).
Correct?
by Zepper
Fri May 21, 2021 11:02 am
Forum: NESemdev
Topic: Namco 163 audio?
Replies: 16
Views: 3668

Re: Namco 163 audio?

I'm using Disch' mapper 19 doc too. About the frequency/channel clock, Disch didn't mention "at every 15 CPU cycles", but a frequency formula for CPU cycles: $F0000 * (E+1) Cycs = ------------------ F I wonder if each channel is clocked (frequency--) at every 15 CPU cycles ... or not?
by Zepper
Thu May 20, 2021 3:00 pm
Forum: NESemdev
Topic: Namco 163 audio?
Replies: 16
Views: 3668

Re: Namco 163 audio?

Ok.

2. At every 15 CPU cycles, channel 8 is updated, then channel 7 after +15 cycles, then channel 6... and so on?
by Zepper
Thu May 20, 2021 2:52 pm
Forum: NESemdev
Topic: Namco 163 audio?
Replies: 16
Views: 3668

Namco 163 audio?

http://wiki.nesdev.com/w/index.php/Namco_163_audio

1. What is 'x' in this expression?
* sample(x) = (w[x/2] >> ((x&1)*4)) & $0F
by Zepper
Tue May 18, 2021 6:06 pm
Forum: NESemdev
Topic: mapper 19?
Replies: 8
Views: 2732

Re: mapper 19?

I though about "the last32 banks" out of a total of 64, for example... and how they would be selectable.
Sorry for the language barrier.
Thanks for the help.
by Zepper
Tue May 18, 2021 3:26 pm
Forum: NESemdev
Topic: mapper 19?
Replies: 8
Views: 2732

mapper 19?

http://wiki.nesdev.com/w/index.php/INES_Mapper_019 1. Writes to $C000-$C7FF affects $2000-$23FF, and "Values ≥ $E0 denote NES NTRAM if" is set to "always". What happens if a value < $E0 is written there? Is possible to map CHR ROM/RAM in the nametables' space? HOW??? 2. What means "Pages $E0-$FF are...
by Zepper
Mon May 17, 2021 6:57 am
Forum: NESemdev
Topic: Slight timing(?) issue
Replies: 14
Views: 3179

Re: Slight timing(?) issue

I have the same problem with scanline test, but no shaking.