Search found 147 matches

by SusiKette
Wed Jul 27, 2022 3:43 am
Forum: NESemdev
Topic: Mesen - NES Emulator
Replies: 990
Views: 609585

Re: Mesen - NES Emulator

Is it possible to make Mesen not clear the CDL file when resetting a game?
by SusiKette
Fri Mar 11, 2022 12:05 am
Forum: Newbie Help Center
Topic: What does this section of a subroutine do?
Replies: 4
Views: 558

Re: What does this section of a subroutine do?

I'm assuming this way of normalizing the vector is not accurate, but rather a approximation. I have noticed that bullets fired at player are fired at double speed at certain distances between the player and the enemy that fired it. I'm assuming this is a side effect of the approximation.
by SusiKette
Fri Mar 11, 2022 12:02 am
Forum: Newbie Help Center
Topic: Why do some NES games have a bunch of JMP instructions at the beginning of a bank?
Replies: 2
Views: 579

Why do some NES games have a bunch of JMP instructions at the beginning of a bank?

I've seen some NES games have a list of JMP instructions at the beginning of a PRG bank. These games seem to jump to these instructions from the fixed bank(s) that then jump to a subroutine in the bank. I would get this if these banks were not fixed in code (swapped bank would depend on a variable),...
by SusiKette
Tue Feb 22, 2022 10:56 am
Forum: Newbie Help Center
Topic: What does this section of a subroutine do?
Replies: 4
Views: 558

What does this section of a subroutine do?

I found this subroutine in RECCA. Based on when this subroutine is used it calculates the direction from object to player and shifts the result left x times. The part I don't get is from $ECB9 to $ECD3 . My best guess is that it is supposed to normalize the values, but still, I don't understand why ...
by SusiKette
Thu Dec 30, 2021 10:29 pm
Forum: NESdev
Topic: Is there an assembler that supports unit testing?
Replies: 17
Views: 2232

Re: Is there an assembler that supports unit testing?

Forking an emulator and wrapping some kind of scripting language around it, where the scripting language contains instructions you write on how to preload the NES's memory with test data, how to initialize mappers, etc, then points the emulated CPU at the code you want to test, then emulates until ...
by SusiKette
Tue Dec 28, 2021 4:00 am
Forum: NESdev
Topic: Is there an assembler that supports unit testing?
Replies: 17
Views: 2232

Is there an assembler that supports unit testing?

I was writing unit tests at work today, which made me wonder if unit testing is currently possible to do in 6502. It would be definitely useful for keeping your code working right, especially when you need to edit something.
by SusiKette
Sun Mar 14, 2021 9:40 am
Forum: NESemdev
Topic: VRC7 discoveries
Replies: 19
Views: 9264

Re: VRC7 discoveries

Have you seen my YM2413 emulation code (https://github.com/nukeykt/Nuked-OPLL), it is based on VRC7 die analysis as well. Would be nice to cross check our findings. Sure. I'm not very good at reading C++ code so reading it might take some time. By the way; Were you able to figure out the connection...
by SusiKette
Thu Mar 11, 2021 2:50 pm
Forum: NESemdev
Topic: VRC7 discoveries
Replies: 19
Views: 9264

Re: VRC7 discoveries

I just found out how the VRC7 disables the channels 7-9. I marked where the different channel's carriers and modulator's were at a given time (eg when phase generator outputs ch1 modulator's phase), what each module gets as input and what they output. I was able to use that to compare different inpu...
by SusiKette
Fri Mar 05, 2021 3:21 pm
Forum: NESemdev
Topic: VRC7 discoveries
Replies: 19
Views: 9264

Re: VRC7 discoveries

While looking around the die, I found that the data output multiplexer (which also is used to dump the instruments) has one output option that outputs only two bits. These seem to output serial data from different modules of the chip. Bit 0 outputs lower 9 bits of phase (there are 18 bits total and ...
by SusiKette
Sun Feb 21, 2021 10:36 am
Forum: NESemdev
Topic: VRC7 discoveries
Replies: 19
Views: 9264

Re: VRC7 discoveries

I took a look at the timing logic and I realized that the counter that keeps track of the shift register position actually only resets every 18 cycles instead of 9 cycles like I originally thought. The timing sequence itself is 18 cycles long. The shift register is writable only on the first 9 cycle...
by SusiKette
Thu Feb 18, 2021 3:13 pm
Forum: NESemdev
Topic: VRC7 discoveries
Replies: 19
Views: 9264

Re: VRC7 discoveries

Ben Boldt wrote: Thu Feb 18, 2021 2:48 pm Do you see any possible detection of register $9008 on the VRC7 die?
I have checked the address decoder already, but I might need some elaboration on what you mean.
by SusiKette
Mon Feb 15, 2021 5:25 pm
Forum: NESemdev
Topic: VRC7 discoveries
Replies: 19
Views: 9264

Re: VRC7 discoveries

The official YM2413 datasheet claims 84 master clock cycles. Since the VRC7 runs at twice the 2A03 CPU clock ... 42. Oh? I have only seen a datasheet of YM2413 where the only thing given in cycles is the reset pulse width. Do you know where to find this datasheet that list this info? Also, accordin...
by SusiKette
Mon Feb 15, 2021 3:56 pm
Forum: NESemdev
Topic: VRC7 discoveries
Replies: 19
Views: 9264

VRC7 discoveries

I recently got back to inspecting the die shot of VRC7 and I found out few things that might be relevant to emulating the chip (or just in general interesting observations). I don't think any of these are mentioned on the wiki page either (or anywhere else as far as I have read). While VRC7's master...
by SusiKette
Fri Dec 25, 2020 4:05 am
Forum: NES Music
Topic: Is it possible to mix DMC samples in software?
Replies: 5
Views: 4517

Is it possible to mix DMC samples in software?

I'm not sure if there are mappers that can map CHR-RAM to ROM area, but I was wondering if there is a way to mix two DMC samples in software an put the result in CHR-RAM in area where the DMC channel can play it? If there is a way, I don't think simply adding the samples together would work, which i...
by SusiKette
Fri Dec 25, 2020 2:55 am
Forum: NESemdev
Topic: Emulator with disassembly capability
Replies: 4
Views: 3506

Re: Emulator with disassembly capability

I don't remember mesen having a disassembly feature (unless it was added just recently). I don't mean disassembly as in begin able to see the code in the debugger. I mean it as in disassembling the code into text files (and maybe chr and dmc files too).