Search found 216 matches

by za909
Thu Mar 21, 2019 1:11 am
Forum: NES Music
Topic: Blargg's saw wave DPCM IRQ demo in NSF2
Replies: 1
Views: 7956

Re: Blargg's saw wave DPCM IRQ demo in NSF2

This is quite a significant development. The implementation of the things like SuperNSF and Deflemask drivers could become much better organized by using the cycle-IRQ feature.
by za909
Wed Mar 20, 2019 2:57 am
Forum: Other Retro Dev
Topic: PC Engine specifics
Replies: 21
Views: 25732

Re: PC Engine specifics

This would be nice; I tried to do this a few years back but got hung up on some things. As for merging it into asm6f, I wouldn't be against it, but a decent way to set the target would be needed. (Probably best discussed elsewhere when the time comes.) That is basically why I said "soon", but didn'...
by za909
Mon Mar 18, 2019 2:31 pm
Forum: Other Retro Dev
Topic: PC Engine specifics
Replies: 21
Views: 25732

Re: PC Engine specifics

Thanks for the replies, I will see what I can get out of the audio knowing the fact that there really isn't a good way to avoid that phase misalignment... (except for that 1 in 32 chance where it will like up perfectly with the wave phase). I have since made a small fork of the open source ASM6 to s...
by za909
Thu Mar 14, 2019 12:44 am
Forum: Other Retro Dev
Topic: PC Engine specifics
Replies: 21
Views: 25732

Re: PC Engine specifics

Dear all, thank you for the responses, they are all extremely helpful, so I need to make sure to save these specifics for the future, especially the transfer instructions clobbering the X and Y registers, which I would've no doubt run into otherwise. I wouldn't be surprised if ST0, ST1, and ST2 clob...
by za909
Sun Mar 10, 2019 4:08 am
Forum: Other Retro Dev
Topic: PC Engine specifics
Replies: 21
Views: 25732

PC Engine specifics

Hi, I have a growing interest in working with the PC Engine, and having read the most common documentation out there (MagicKit, MagicEngine, etc.) I have a few fairly specific questions that I could not find the answers to. I suspect that the system has not been torn to shreds as much as the NES, so...
by za909
Sat Feb 02, 2019 5:16 am
Forum: Other Retro Dev
Topic: PC Engine waveform channel updates
Replies: 8
Views: 19532

Re: PC Engine waveform channel updates

I have since tried to do the same on the FDS, a system where I know that the channel has to be halted and reset to change the waveform, and the results are oddly clear with very little artifacts added. This is a promising next step.
by za909
Sat Jan 05, 2019 2:32 am
Forum: Newbie Help Center
Topic: Help understanding sprite-0
Replies: 23
Views: 7859

Re: Help understanding sprite-0

A slightly less complicated, but also less effective way to "get more colors" is to use the PPU color emphasis bits . It's not nearly as useful as an actually changed palette, but it lets you get a few more tones (or a few washed-out colors by combining them with the grayscale bit) out of your alrea...
by za909
Thu Nov 22, 2018 3:45 am
Forum: NESdev
Topic: Interleaving on the NES
Replies: 7
Views: 5558

Re: Interleaving on the NES

As it turns out, my original guess of being able to save 100-150 cycles was an extremely generous assumption. Currently, in the middle of redesigning the PCM code to accomodate this interpreter, it seems that the interpreter needs to be aware of how many cycles it has to spend before it has to retur...
by za909
Tue Nov 20, 2018 1:57 am
Forum: SNESdev
Topic: Need sound help emulating NES on SNES
Replies: 33
Views: 25677

Re: Need sound help emulating NES on SNES

Some games do attempt to silence the triangle channel in weird ways that might cause some issues: - Mega Man and Mega Man 2, plus other Capcom games from around that time silence the triangle by writing 0 to the period register, some even use $4015 afterwards, it's really odd, but it makes a popping...
by za909
Wed Nov 07, 2018 5:16 am
Forum: Newbie Help Center
Topic: Trying to understand PPU Registers
Replies: 15
Views: 6487

Re: Trying to understand PPU Registers

Your decoder has to look at the right bits (pins) to determine when to enable the peripheral and allow traffic between the CPU and the peripheral. My super simple 64kB PRG ROM setup requires a 1-bit register to select which 32kB half of the ROM I want the system to see at $8000-$FFFF. Since $8000-$F...
by za909
Wed Nov 07, 2018 3:35 am
Forum: NESdev
Topic: Interleaving on the NES
Replies: 7
Views: 5558

Re: Interleaving on the NES

Possible tasks that could be made to run in constant time: * Filling buffers for scrolling * Filling buffers for sprites Thanks for the ideas. Thankfully I wouldn't even have scrolling updates because the rooms would be non-scrolling screens with fadeouts for transitioning, where the game draws the...
by za909
Tue Nov 06, 2018 2:36 pm
Forum: NESdev
Topic: Interleaving on the NES
Replies: 7
Views: 5558

Interleaving on the NES

I have a long-going project to use the DMC IRQ to stream PCM data at 8.2kHz while still having enough time to run a game (with the tasks spread out across two frames for 30FPS). However, this is done by sitting around in the IRQ handler so that I can land another $4011 write right in between two IRQ...
by za909
Fri Oct 05, 2018 1:33 am
Forum: NESdev
Topic: Problem converting 256 KB MMC-1 to 512 KB MMC-1
Replies: 55
Views: 15129

Re: Problem converting 256 KB MMC-1 to 512 KB MMC-1

That makes sense, it's a way to assess how far people have come with reverse-engineering the hardware if you try to stick to the same limits on hardware as developer X, but you are still able to do more thanks to discoveries since then, and more time to spend on managing the available resources bett...
by za909
Thu Oct 04, 2018 3:26 am
Forum: NESdev
Topic: Fun with strange bugs!
Replies: 22
Views: 8206

Re: Fun with strange bugs!

It just happens too often that you accidentally end up using zero page memory access instead of an immediate value. Had the 6502 assembly language been originally developed to require you to prefix both immedate values and memory accesses, this kind of mistake would slip through much less often. Whe...
by za909
Wed Oct 03, 2018 7:24 am
Forum: NES Graphics
Topic: what does 8 bit graphics mean
Replies: 43
Views: 32575

Re: what does 8 bit graphics mean

When someone says NES "framebuffer", I immediately think of Videomation and Oeka Kids , which are designed to store a full screen framebuffer in CHR RAM. After that, I think of pseudo-framebuffers as used in Qix , Hatris , the Block Out prototype, 3D Block , and the like. If I'm not mistaken, it co...