11 March 2016 - Forum Rules
Started by Gyroballer, February 20, 2019, 11:12:05 PM
LDA ($40), Y @0123 = #$A0
Quote from: Gyroballer on February 21, 2019, 03:13:29 PMI used this* last night and was able to get to the point where the CPU/RAM was snapping during writing text, but if I picked a specific value, it was snapping 1 tile before or after
Quote from: Psyklax on February 21, 2019, 05:24:35 PMNot sure I understand the problem you're having.
Quote from: nesrocks on February 22, 2019, 12:02:46 PMYou're gonna have to look in the PPU memory, find the address for one specific letter, then set a breakpoint to a write to that PPU address and work your way back from there to reverse engineer what it is doing.
Quote from: cccmar on February 22, 2019, 01:37:12 PMI believe that the text in DB 3 is stored in CHR-ROM, kinda like what Culture Brain tend to do with their games, so the pointers are not normal. If that's the case, even just finding and dumping it will be very difficult. Maybe DvD or some other hacker who's done that could give you some tips there.
Quote from: nesrocks on February 22, 2019, 01:56:48 PMThere are four nametables on PPU memory: 0x2000-0x23ff, 0x2400-0x27ff, 0x2800-0x2bff and 0x2c00-0x2fff. If it's writing to 0x2084, it's in the first one (top left).By reverse engineer I mean that you need to set a breakpoint to a write to that address and then read the assembly code and understand what it is doing and where the value is coming from. I admit I hadn't read the thread and Psyklax had already said basically exactly the same thing! Sorry $204 and $203 are the temporary bytes to store the 16bit sized address for where to write to the nametable (since addresses are 16 bit and each byte is 8 bits it needs two bytes).$205 is the data to write there.That data is coming from $2007, which is the register to write PPU data to. I don't know exactly what is going on there, but this is the line that does it07:E0F9:AD 07 20 LDA PPU_DATA = #$B7 (A becomes 02 after this read)07:E0FC:9D 64 02 STA $0264,X @ $026D = #$93Maybe it has to do with this, but I'm not sure http://wiki.nesdev.com/w/index.php/Reading_2007_during_rendering
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