Search found 5 matches

by Dugongue
Sat May 30, 2020 6:02 am
Forum: NESdev
Topic: Trying to understand the purpose of this operation:
Replies: 6
Views: 1590

Re: Trying to understand the purpose of this operation:

It's odd to see two NOP's replaced with a seemingly useless LDY immediate as TAY happens after the JMP. Sorry I didn't explain that very well, the NOPs I manually added into the US ROM to see if it resulted in any difference in the trace. The JP rom has no operation there at all. My guess: they cha...
by Dugongue
Fri May 29, 2020 6:05 pm
Forum: NESdev
Topic: Trying to understand the purpose of this operation:
Replies: 6
Views: 1590

Trying to understand the purpose of this operation:

So every once in a while I do a side-by-side comparison of the JP/US versions of games to work out what's changed between revisions. I was looking at the JP and US version of Blaster Master, specifically Page 6 which contains the AI code for objects in the side/tank view sections. I'm not fully thro...
by Dugongue
Thu Mar 07, 2019 6:41 pm
Forum: NESdev
Topic: Is this available anywhere? (Homebrew ROM to display memory)
Replies: 4
Views: 4151

Is this available anywhere? (Homebrew ROM to display memory)

Does there exist a ROM that simply displays a section of memory from their initial state at bootup? For example, displaying the range of $000-$FFF in a scrollable list. I've been curious to investigate games that use unitialized memory, & it occurs to me if such a ROM existed & were manufactured int...
by Dugongue
Thu May 24, 2018 4:15 pm
Forum: Newbie Help Center
Topic: Trying ROM Disassembly & getting lots of Invalid Opcodes
Replies: 9
Views: 4555

Trying ROM Disassembly & getting lots of Invalid Opcodes

Hi, I'm trying to teach myself to read NES assembly code & I hit a snag. I used disasm6 v1.5, both with and without use of a CDL file from FCEUX and the resultant ASM file is chock full of invalid Opcode errors. Here is a sample section: bvc __83aa ; $83e8: 50 c0 cld ; $83ea: d8 .hex ef a3 40 ; $83e...
by Dugongue
Wed Apr 18, 2018 4:56 pm
Forum: NESemdev
Topic: Miracle Piano in FCEUX
Replies: 3
Views: 4845

Re: Miracle Piano in FCEUX

Hey thanks for letting me know about this. I'm going to try and go back to the lessons I couldn't finish now. I've seen some other minor bugs like notes being transcribed incorrectly in certain sections too. I also own the SNES cable so I might see if these bugs exist on that version too, or even th...