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I have decided to use packbits for my nametable compression. I have learned the basics about scrolling and I'm really glad to see that it isn't as difficult as I thought. I am working on a basic horizontal scrolling game (one way). The thing is, I had an idea of what to do for updating the name-tabl...

My RLE idea is to store 2x2 meta tiles for my backgrounds. The idea I came up with is to have the left nibble be the repeat number and the right nibble to be the tile number. Instead of the right nibble being 0 - F, it would be 0-9. A-F in the right nibble would be a bank switch for the 10 tileset. ...

Yup, it was the registers alright. I imagine that A was being modified somewhere and the JumpEngine was hoping off to who-knows-where. I added the push/pulls to the NMI and everything works well. I do need to breakpoint my code, but I haven't yet figured that out with my emulator. Any suggestions on...

What do TestSound1 and 2 do? JumpEngine eats the first address on the stack to return to, so unless this routine itself was JSR'd to.... I'm calling the JumpEngine routine from my control handler. It is run during NMI. Is it possible that it isn't completing the jump before the next NMI is called? ...

tokumaru wrote:

Dwedit wrote:This code has no way to find the address of the jump table, so it assumes you saved a 16-bit value at address 4 and 5.

No it doesn't, it uses the return address as the address for the jump table, which is why the addresses are defined right after the JSR.

So why doesn't it work?

I'm running into some strange issues with my code. I came across the following code in the SMB1 source: JumpEngine: asl ;shift bit from contents of A tay pla ;pull saved return address from stack sta $04 ;save to indirect pla sta $05 iny lda ($04),y ;load pointer from indirect sta $06 ;note that if ...

Try the 6502 macroassembler . A small guide I wrote about it. Not sure if that's quite in the vein you're looking for, but you can write, and run pretty immediately as well as step through it. Thank you, I've been using this lately actually. I'm just set in my Linux / Commandline ways ;) Glad to se...

As a fan of Ruby, I would love to have something within the vein of IRB to quickly test my code so that I can rapidly learn the language. I've messed around with apple ii emulators and seen videos on youtube where you can quickly write to memory and test your code. Oddly enough, I haven't found a mo...

I am trying to understand control flow in 6502 assembly. Say I have the following code: ; using asm6 ControlFlow: lda mem cmp #1 bne @sub_one cmp #2 bne @sub_two @sub_one: ; sub routine one goes here jmp @done ; <-------------- without this jmp, @sub_two will execute @sub_two: ; sub routine two goes...

For instance, how do I return control to where I left off? Is there some way to combine JMP with RTS by pushing the program counter on the stack? Sure there is: jsr Jump (...) Jump: jmp (vector) I see that I didn't explain my intention clearly, thats on me... I want to use the vector within the tab...

A method I've used for timed events is to use a small structure of addresses with counters. Every NMI they are all checked: Any counters that are set are decremented and any that hit zero are called (the addresses part). The callback procedure that is called can then do it's thing, and reset it's t...

I haven't been able to find any utilities that allow you to see your .chr sprites animate. I am in the middle of developing the sprites for my main character. I have an idea of what it will look like, but I think that development would be more rapid if I could "see" it in motion. Of course...

I am currently using NESASM, and I am restructuring the code from the Nerdy Nights tutorial to use separate files. I have taken the code from the tutorial that very simply displays a 2 x 2 sprite that moves when you use the controller. I have read up on the NESASM readme file and I still don't grasp...

And you can use .db, but I mostly load files with .include as 1KB of .db statements is pretty just....bad programming/data handling. In your .include file, are you entering it as just a stream of values? Do you need to label your other file, or can you put comma separated hex values like this: ; in...

I have been learning with the Nerdy Nights NES tutorials for a few weeks and have some questions not really clarified in the tuts... I don't really get the logic behind the following: http://www.nintendoagemedia.com/users/142/photobucket/F837623F-9C98-E50B-F4D377EE82FA2BDA.png You can see there are ...