Search found 193 matches

by za909
Sun Sep 01, 2019 12:53 am
Forum: NESdev
Topic: The truth about the black entries of the NTSC NES:
Replies: 12
Views: 6117

Re: The truth about the black entries of the NTSC NES:

I too have been ignorant of this information until now, but one question remains for me about 1D. It's nice to have it affected by the emphasis bits, but is it "safe" on TVs when not all three bits are set at once?
by za909
Mon Jun 10, 2019 8:03 am
Forum: NES Music
Topic: Mega Man 3 Music Editing
Replies: 2
Views: 3890

Re: Mega Man 3 Music Editing

This forum is not really geared towards ROM hacking, but you might find this useful.
by za909
Tue Jun 04, 2019 1:01 pm
Forum: Homebrew Projects
Topic: Raspberry pi in a NES cart
Replies: 44
Views: 29707

Re: Raspberry pi in a NES cart

I was wondering about music - I've seen PCM demos for the NES but I'd (probably) need another FX2LP to stream data in and out of the CPU bus. If you want to keep the NES unmodded, try to drive the IRQ line with your external hardware and put the pre-mixed sample for the DAC on a memory-mapped I/O p...
by za909
Mon Jun 03, 2019 11:31 pm
Forum: NESdev
Topic: Passing an array of arguments
Replies: 0
Views: 6756

Passing an array of arguments

Yesterday as I was trying to figure out a way to efficiently create multiple "forks" of the same enemies that would behave differently based on their ID, I've come across the need to pass one of multiple sets of arguments to my function that handles sine-wave motion. Since the enemy needs to find it...
by za909
Tue May 28, 2019 4:19 am
Forum: NESdev
Topic: Updating APU Regs Multiple Times Per Frame
Replies: 28
Views: 18629

Re: Updating APU Regs Multiple Times Per Frame

Even if the NMI handler allows IRQs to get through, distortion from OAM DMA is still very hard, if not impossible to mitigate completely. Only the DMC DMA can interrupt it, so I suppose one solution is to find a good "interpolation" DMC sample to play before starting OAM DMA, or to adjust the sample...
by za909
Mon May 27, 2019 6:51 am
Forum: NESdev
Topic: Updating APU Regs Multiple Times Per Frame
Replies: 28
Views: 18629

Re: Updating APU Regs Multiple Times Per Frame

My two cents' worth is that you don't need to run the ENTIRE sound engine multiple time per frame to achieve interesting effects, just put some subroutines in an IRQ that modulate pitch, duty cycle or volume. Also, referring to tips about using the DMC IRQ: If you don't want to use samples otherwise...
by za909
Mon May 20, 2019 1:05 am
Forum: NESdev
Topic: Why not read controllers in NMI?
Replies: 50
Views: 43933

Re: Why not read controllers in NMI?

Controller reads in NMI seemed like a natural thing for me to do. Since I use the DMC interrupt for scroll splits, there is no reason to have the DMC run during VBlank, so I'm free to stop it, read the controller in NMI in a consistent number of cycles this way (no need for DMC glitch fix) and resta...
by za909
Thu May 16, 2019 3:21 am
Forum: Newbie Help Center
Topic: Techniques to detect scanline
Replies: 14
Views: 10109

Re: Techniques to detect scanline

Some time ago I proposed the idea of polling the noise channel's length counter state bit in $4015 to wait for approximately half of the visible scalines to be drawn (depends on the timing difference between the CPU and the APU frame sequencer). It's not the most useful thing in the world and I neve...
by za909
Wed May 15, 2019 1:14 am
Forum: NESdev
Topic: Efficient technique for improving DMC timing accuracy
Replies: 20
Views: 13074

Re: Efficient technique for improving DMC timing accuracy

This is some great news! If this technique is demonstrated to produce those results, I might just have to go back and re-write my IRQ handler. For now, I could get away with the 2-3 scanlines of jitter (somehow I could only get this work with rate $C) by designing my graphics such that solid colors ...
by za909
Fri May 10, 2019 1:11 am
Forum: NESdev
Topic: 4-bit Samples on the Pulse Channels
Replies: 4
Views: 5400

Re: 4-bit Samples on the Pulse Channels

I think if you write to $4003/$4007 the phase will reset, so doing this "constantly" will ensure a DC output, leading to the effect you want. I'm not sure of the phase, either duty cycles %00, %01, %10 will work and %11 won't work, or it's the oposite. This is actually the only difference between d...
by za909
Thu May 09, 2019 5:33 am
Forum: NESdev
Topic: 4-bit Samples on the Pulse Channels
Replies: 4
Views: 5400

4-bit Samples on the Pulse Channels

Hi there, I've had yet another idea to cram more into my DMC IRQ-based PCM music player, since a scheduler meant to handle game logic tasks during a wait inside the IRQ handler proved to be of very little added efficiency to a game. Since I need to wait more than 100 cycles / IRQ, I thought I could ...
by za909
Sun Apr 21, 2019 2:22 am
Forum: NESdev
Topic: Why not mapper 11 or 66 ?
Replies: 53
Views: 24083

Re: Why not mapper 11 or 66 ?

I can agree that UxROM is very attactive to jump to after messing around with NROM. If you look at it, some of the early "great games" of the system used it like Castlevania or Mega Man. It's much easier to get into at first, since you don't have to worry about any kind of volatile trampoline routin...
by za909
Sun Apr 14, 2019 4:40 am
Forum: Newbie Help Center
Topic: Increasing x_pos by 4, but sprite can move outside of grid?
Replies: 12
Views: 5667

Re: Increasing x_pos by 4, but sprite can move outside of gr

If you want easy rectangular hitboxes, try to limit the fastest speed anything can go at to be less than the smallest length of any hitbox's side. Otherwise, like mentioned before, objects may pass through other objects if they go too fast (in one frame the object is to the left of something, and in...
by za909
Fri Apr 12, 2019 11:31 am
Forum: NESdev
Topic: How many times can the NES change scrolling in a frame?
Replies: 32
Views: 18343

Re: How many times can the NES change scrolling in a frame?

Something that always gets on my nerves is when people see raster effects on the SNES, they think it's either "mode 7" or the "FX chip". There seems to be this false myth out there that "the SNES can't do anything special without outside help", but then again, I think the opposite is also true wher...
by za909
Thu Apr 11, 2019 11:39 pm
Forum: NESdev
Topic: Namespacing symbols used by an ASM6 library
Replies: 18
Views: 20947

Re: Namespacing symbols used by an ASM6 library

Since my ASM6 projects are rarely that big, I tend not to use any kind of scope prefix if the variables or constants are unique enough. Why would I prefix a musical note constant if I know there really is no reason to name anything else in the project a "D_2" or anything similar. So my custom music ...