Search found 249 matches

by za909
Tue Mar 26, 2024 12:12 pm
Forum: Newbie Help Center
Topic: Help with 2-byte indexing lookup table
Replies: 5
Views: 249

Re: Help with 2-byte indexing lookup table

Also, having two separate lookup tables for low and high values is almost always more efficient and remove the hassle to have to multiply the result by two. Agreed, it makes the data a bit more cumbersome to maintain but you gain a bit of performance, space, and you are not restricted to 128 entrie...
by za909
Wed Jun 07, 2023 8:54 am
Forum: NESdev
Topic: Stack juggling? Is this dangerous?
Replies: 13
Views: 1189

Stack juggling? Is this dangerous?

Hi, the first question is, does the thing I'm doing have a better name? I have designed a PPU update buffer structure for my game in the $0100 page, and as I was starting to work on the NMI side of this system I realized that I need to suppress interrupts while I am working with another stack. Or do...
by za909
Tue Feb 14, 2023 8:15 am
Forum: NES Music
Topic: VRC7 Patch Switching
Replies: 2
Views: 1402

VRC7 Patch Switching

Since the emergence of Furnace tracker, it's become quite easy to go wild with sound chips in ways people haven't really done before. One of such things is VRC7 (and OPLL) patch switching where the patch selector is changed while the sound is playing. Some parameters, like feedback and multipliers a...
by za909
Mon Feb 13, 2023 3:54 am
Forum: NESdev
Topic: Expansion audio on NES?
Replies: 6
Views: 1133

Re: Expansion audio on NES?

It depends on what you're planning to do. An UxROM or BxROM board can be more than sufficient in most cases, and even if you need some kind of IRQ support you can use the DMC IRQ trick to get yourself a crude timer for parallax scrolling or fixed status bar effects. The best part about discrete logi...
by za909
Sat Jan 28, 2023 5:08 pm
Forum: NES Music
Topic: Issues with musical tones via PCM ($4011 writes)
Replies: 16
Views: 3328

Re: Issues with musical tones via PCM ($4011 writes)

Something you might want to try to find a workaround for is the issue with OAM DMA. If the program uses sprites your code has to ask the CPU to copy a page of the CPU memory space to the special sprite RAM (OAM) once per frame. During this time the CPU is stalled for 512/513 cycles to automatically ...
by za909
Mon Jan 16, 2023 3:36 am
Forum: General Stuff
Topic: Stamps Back - Documentary about gaming behind the Iron Curtain in Hungary
Replies: 1
Views: 755

Stamps Back - Documentary about gaming behind the Iron Curtain in Hungary

This documentary was recently on for a limited number or showings at local cinemas in Budapest. I was there with friends, and the producer told us it would later be available for free on Youtube. I think people here might be interested in it. It's mostly about C64 and other computer platforms and th...
by za909
Sun Jan 08, 2023 5:01 pm
Forum: NES Music
Topic: We are looking for a musician for our finished game
Replies: 4
Views: 1538

Re: We are looking for a musician for our finished game

Seems interesting, the one part that I need to have cleared up for me is how you intend to do a conversion if at all. Do you need Famitracker modules or text output and is there an automatic conversion method applied to those? For reference, here is a playlist of the Nova the Squirrel soundtrack I m...
by za909
Sun Jan 08, 2023 3:48 pm
Forum: NESdev
Topic: Game Genie sound pitch shifting, possible? (Question)
Replies: 21
Views: 1560

Re: Game Genie sound pitch shifting, possible? (Question)

The thing about Mega Man 1 and 2 is that I believe they never touch the pulse sweep registers, so whatever was left there stays there. This isn't an issue normally other than that the sweep causes the pulses to immediately stop when going to the lowest octave, as described in known errata. The true ...
by za909
Sun Oct 16, 2022 10:52 am
Forum: NES Music
Topic: Examples of Game Logic Modulating Music?
Replies: 14
Views: 3567

Re: Examples of Game Logic Modulating Music?

I have once done an experiment like this, but that project is on hold for now. The game logic would change the global transpose variable every x frames to make the pitch go up and down on the continue screen, which would just be the same fours beats of data repeated over and over again to save some ...
by za909
Sun Oct 16, 2022 4:31 am
Forum: NESdev
Topic: Designing your discrete logic mapper
Replies: 4
Views: 1050

Re: Designing your discrete logic mapper

You'll need an extra OR gate if you actually want a fully fixed bank - each OR gate only handles four bits of latch. Right, I was thinking of the original UxROM boards. I basically need the logic to say if (cpu_R/W & (cpu_A15 & cpu_A14 )) | (latch_O0 & latch_O1 & latch_O2 & latc...
by za909
Sun Oct 09, 2022 3:18 am
Forum: NESdev
Topic: Designing your discrete logic mapper
Replies: 4
Views: 1050

Designing your discrete logic mapper

I've been having some semi-serious thought experiments about designing a cheap and very specific-purpose mapper to be able to create something like UNROM but with a CPU cycle-based IRQ. Having done my old PCM player projects that ran on the DPCM IRQ, I thought that taking it to the next level and no...
by za909
Sun Aug 21, 2022 4:32 am
Forum: NESemdev
Topic: Famicom AV, PAL NES & Dendy chips decapsulation (progress!)
Replies: 43
Views: 81420

Re: Famicom AV, PAL NES & Dendy chips decapsulation (progress!)

The TA-02NP Works with pin 17: Video mode: 50Hz (GND) / 60Hz (5V) https://www.youtube.com/watch?v=7pEY6nnKFuo Anything you can think to add to the descriptions here: nesdevwiki:Known PPU revisions and nesdevwiki:Known CPU revisions ? Necrobump but I have some valid questions here. Does this affect ...
by za909
Tue May 17, 2022 4:27 am
Forum: General Stuff
Topic: What would you change about the NES?
Replies: 54
Views: 6672

Re: What would you change about the NES?

Here's a few things I would change, mostly I would just correct some of the errata and finish what was left unfinished... Fix PPU errata like Sprite overflow flag being unreliable, OAM DRAM should be auto-refreshed, 6-bit RGB color space (like on SMS) but we can keep the 2bpp as is Make PPU Slave Mo...
by za909
Tue May 10, 2022 6:26 am
Forum: Other Retro Dev
Topic: PC-Engine General questions
Replies: 17
Views: 3076

Re: PC-Engine General questions

I am once again trying to "hack" the system and go against its design philosophy of only allowing you to use a lowest sprite size of 16x16. My mind just can't break away from the NES-style 8x8 tile philosophy so I tried to figure out a way to essentially store both BG and SP graphics in th...
by za909
Tue May 10, 2022 6:08 am
Forum: Other Retro Dev
Topic: PC-Engine General questions
Replies: 17
Views: 3076

Re: PC-Engine General questions

As a fun teaser for what I have in store, here's a test of my code using the Timer interrupt to reset the wave phase on a channel playing a pitch bending sine wave. This creates a hard sync effect similar to what's possible on a SID chip. I'm fairly certain nobody has done this sort of thing on the...