Search found 224 matches

by za909
Thu Aug 28, 2014 2:27 am
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

That does seem like a good idea now that I realised the operation of the stack is not lethal to data you just write to $0100-$01FF. If pushing and pulling only affect S it's fine for this. I thought stack affecting operations rotate bytes as well, and whatever is at $0100 is lost if I push something...
by za909
Tue Aug 26, 2014 1:58 am
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

Alright, now comes the final stretch. I got it to work, sort of. The triangle and noise channels work perfectly after a little bit of debugging and adding safety measures, and the whole thing is stable so I just need to find out what's wrong with the pulse channel code. Which brings me to a question...
by za909
Sun Aug 24, 2014 4:34 pm
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

So it's come to this yet again. So many really little things I just need to ask, but thank you all of you for the help up until now, you're aiding me to set sail and explore the amazing waters of asm and it's a wonderful experience (and who knows if I get experienced who's to stop me from moving on ...
by za909
Sun Aug 24, 2014 11:05 am
Forum: NES Hardware and Flash Equipment
Topic: NES controller for Famicom
Replies: 9
Views: 3799

NES controller for Famicom

I've got a question coming in from a friend, basically the thing is, he really hates how short the cables of the Famicom controllers are and wants to know if the standard is the same as the NES controllers, which would make it possible to cut the Famicom and NES controller cables, and solder the NES...
by za909
Fri Aug 22, 2014 8:20 am
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

This lda susoff_flags cpx #$02 bcs ClearPu2 This decides which channel bits have to be cleared. X serves as an index, depending on which channel's turn it is 00 means Pulse 1, 02 means Pulse 2, 04 = Tri, 06 = Noise I don't know why I included the lda, but that's where I load, and then select a value...
by za909
Fri Aug 22, 2014 7:01 am
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

Ah ok, that makes sense. It's just simply the context that made it confusing for me, because the only thing that matters is that certain bits must be cleared by this code, it doesn't matter if I flip them or AND them with the right 2's complement, because when this fires off, both bits are 1 always....
by za909
Fri Aug 22, 2014 1:08 am
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

ORA & EOR vs. ADC & SBC So the situation is the following: Sometimes I need to set or clear certain bits in memory, but without affecting the rest of them. I figured this could be done by simply adding or subtracting in binary, but sometimes that bit is already set/clear, so a remainder is carried o...
by za909
Tue Aug 19, 2014 2:28 am
Forum: Newbie Help Center
Topic: Can't figure out post-indexed indirect addressing
Replies: 2
Views: 1318

Re: Can't figure out post-indexed indirect addressing

You're loading a value from $E704, which is part of the cartridge space, so it'll only happen if there's the $FF as a constant at $E704

Code: Select all

.org $E704

  .db $FF
I don't know which assembler you're using, so you might have to change the .db to .byte
by za909
Tue Aug 19, 2014 1:16 am
Forum: Newbie Help Center
Topic: Questions about implementing samples into DPCM
Replies: 36
Views: 8505

Re: Questions about implementing samples into DPCM

Implementing DPCM *could* be the easiest thing to do if it wasn't for the controller port/PPU data reading bugs introduced (of which you probably only need to worry about the former) But playing a DPCM sample by itself is incredibly easy. First I advise turning it off by writing $0F to $4015 You sim...
by za909
Mon Aug 18, 2014 1:09 pm
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

I never use the length counters for anything. My pulse channels are fed with volume/duty register writes every frame from a table accessed via a table of pointers (these are the instruments), so it's just a matter of always sending the correct bit to keep the length counter disabled. The triangle wi...
by za909
Mon Aug 18, 2014 11:34 am
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

Alright, now I'm at the point where the pulse channel handling is 90% finished, so I need to start thinking about what to do with the triangle. I'm planning to have two modes for it, one with infinitely held notes (but upon reading a delay $00 byte I turn it off with its bit in $4015) and one using ...
by za909
Fri Aug 15, 2014 2:48 am
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

Thank you for your answers, I'd really like to keep this going because programming is such a good remedy for stress for me. (Does anyone else feel that way too?) So really there's not much point in trying to use the D flag. (If you're really that craving for every single bit of memory you can get yo...
by za909
Wed Aug 13, 2014 2:37 pm
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

Thanks, so really in this case it acts as if the accumulator was a sort of "9-bit" register. My first question did not get answered though, I guess you just forgot about it or didn't notice it. No big deal because while I'm at it I feel the need to get the rest out of the way (it might be worth just...
by za909
Tue Aug 12, 2014 1:00 pm
Forum: Newbie Help Center
Topic: Random questions (mostly APU)
Replies: 32
Views: 6732

Re: Random questions (mostly APU)

I have a few pretty easy questions here, since it could save a couple bytes during certain conditional jumps, and additions if it works. So for example if I lda #$00, the zero flag is set. But what happens if I load a non-zero value? Is the zero flag cleared or unaffected? Does the state of the carr...
by za909
Sun Aug 10, 2014 9:07 am
Forum: NESdev
Topic: Reset button, how does it work?
Replies: 10
Views: 4551

Reset button, how does it work?

So I've been wondering if all the reset button on the console does is merely copying the reset vector to the program counter, or more? Does a hardware reset cause any changes to the PPU or the APU (resetting the channel sequencers or whatever) , and if so, does everything return to an unknown state ...