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Whatever the symbols may be, the V symbol ideally should not be identical to the H symbol rotated by 90 degrees.

At the very least, you need to write to $2000 again and set the bottom 2 bits to point at the expected "base" nametable.

I've just made an additional update to the nestest reference log to fix 2 things: 1. The "PPU" column now displays the scanline number first and the pixel number second, because I realized it was confusing to have it the other way around (i.e. it was like showing Seconds,Minuntes instead of Minutes,...

The part that I wonder about the most: how is the game going to access PRG @ 0x40000 - 0x43fff? The fifth bit is usually masked out on roms under 512k w/MMC1. I'm guessing that it expects all of PRG 40000-47FFF to be mapped to CPU $8000-$FFFF if the MMC1 resets in 32KB bank mode. Do you think the c...

As for mapper 268: A CopyNES can dump at most 32 MiB minus 256 bytes in one go, so it's best to dump 16 MiB in each of two goes, and only when outputting to UNIF or headerless files. I need to update my plugin for that, also later. Technically, the limit is 16MB minus 256 bytes per packet , and the...

Hey guys, So I've read about horizontal and vertical mirroring, what exactly those mean I'm not too sure about but what confuses me even more is when I see games on the NESCartDB which say "Mirroring: Mapper CTRL" What does that mean? It just means that nametable mirroring is Mapper C on tr o l led...

From what I understand, the .bank 0 defines an 8 kb chunk of memory, and then we're telling it to select the chunk starting at CPU address $8000, and write all the following code starting at that CPU address. But what is the point of .bank 0, if we're going to just tell the CPU where to start putti...

New feature for Visual 2A03: audio output display. There are now 5 boxes to the right of the memory table which display waveforms for each of the builtin sound channels (square 0, square 1, triangle, noise, PCM); the first 4 are scaled vertically by a factor of 3 (so that they aren't extremely tiny)...

A gets set to 53 in both cases, the result is the same, but my instruction sets the C flag whereas the official log doesn't. I'm scratching my head a little bit on this one. The subtraction is resulting in borrow ($40 - $EB), and that should clear the carry flag (because it's the opposite of how it...

Ice Man wrote: ↑

Thu May 07, 2020 11:32 am

Might want to post pictures of the PCB front and back as well.

This might also tell us if the cartridge is using 3.3V chips instead of 5V ones, which might possibly cause problems with a standard Famicom.

The 8 cycle timing you saw on the wiki includes the page crossing because DCP is a Read-Modify-Write instruction (being based on DEC) and thus always takes the extra cycle for page crossing. Read-Modify-Write instructions (SLO, SRE, RLA, RRA, ISB, DCP) # address R/W description --- ----------- --- -...

With a bit of experimenting, I've figured out what's going on - the loop happens when the PPU starts drawing Sprite pixels on top of a blank Background. It was very briefly shorting the Background and Sprite pixel data together, and since Ground "wins" in NMOS, the sprite pixels were becoming blank ...

The 6502 wasn't designed to be used that way, hence the name, non maskable . "Non-maskable" has nothing to do with interrupts overlapping - it has to do with the fact that NMI ignores the "Interrupt Mask" flag (while IRQs respect it, allowing you to ignore them when you don't want to deal with them).

I've done a round of updates to reorder the transistors driven by pclk0 (edit: and also pclk1), and with an update to the builtin test program, I've confirmed that all 8 sprite render units appear to be functional, at least with 8x8 sprites at Y=0 on the first few scanlines (the X counters and CHR s...

Somehow, I managed to get through nearly all of the 2C02 (except for pclk1/pclk2), though in the process I somehow managed to introduce a rather severe OAM corruption bug when writing to $2003. Of course, considering that writing nonzero values to $2003 is known to cause corruption, but it's not sup...