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 Forum: Newbie Help Center   Topic: Thought ROL/ROR would do this...

Posted: Thu Apr 30, 2015 7:22 am 

Replies: 6
Views: 1362


I have a byte I want to cycle through, where the bits should be shifted with 'wrapping' - like so: #%00000010 --> #%00000001 --> #%10000000 I thought that ROR / ROL worked this way (and opposite), but it does not seem to in this case. Is my understanding flawed, or is it something deeper in the code...

 Forum: Newbie Help Center   Topic: CHR Ram on actual hardware

Posted: Fri Apr 24, 2015 4:17 am 

Replies: 13
Views: 2614


Got it! Awesome info!

Yeah, i get the impression this is how a lot of people handle background tile animation. Might give it a try now that i am aware how easy it is!

 Forum: Newbie Help Center   Topic: CHR Ram on actual hardware

Posted: Thu Apr 23, 2015 6:29 pm 

Replies: 13
Views: 2614


Annnnd it's Memblers FTW! haha. I was doing my CHR-RAM loads prior to setting up my first bank load (it happened in the inits JUST after the chr-ram loads). I would have never thought of that. Awesome. I do have a prg bank table, and a routine to bankswitch. I suppose I'm confused how that also hand...

 Forum: Newbie Help Center   Topic: CHR Ram on actual hardware

Posted: Thu Apr 23, 2015 6:07 am 

Replies: 13
Views: 2614


CHR RAM swapping being done incorrectly or wrong bit order. This won't be a problem with NROM, UNROM, or BNROM, but ASIC mappers used with both CHR ROM and CHR RAM can bankswitch CHR RAM the same way as CHR ROM. MMC1 and MMC3 games are known to do this. What mapper is used? Hm - now that's an inter...

 Forum: Newbie Help Center   Topic: CHR Ram on actual hardware

 Post subject: CHR Ram on actual hardware
Posted: Wed Apr 22, 2015 4:35 pm 

Replies: 13
Views: 2614


So I was fairly sure this was my own beat up NES causing the problem, plus I thought I'd resolved it (magically), but enough signs point to that not being the case that I'm compelled to ask about it. I'm using CHR-RAM. At the start of the game, I turn the drawing off (and in NMI at the end, even hav...

 Forum: Newbie Help Center   Topic: VRAM buffer?

 Post subject: VRAM buffer?
Posted: Wed Apr 22, 2015 7:29 am 

Replies: 3
Views: 1310


I'm looking for a starting point here as to best methods for creating a simple vram buffer. I understand the reasons to have one; the limited amount of time for graphical updates in the vBlank. So for things like HUD updates, background graphic changes, etc...I get it. I get that the concept would b...

 Forum: Newbie Help Center   Topic: Wonky compare issue

 Post subject: Re: Wonky compare issue
Posted: Sat Apr 18, 2015 10:33 am 

Replies: 10
Views: 2133


Oops yeah that's what i meant. Alright...thats good info. I'll play a little with this today. **** I seem to have no problem doing the compare with a positive number but can't seem to get this working with a negative one. The number should swing from a potential positive value to a potential negativ...

 Forum: Newbie Help Center   Topic: Wonky compare issue

 Post subject: Re: Wonky compare issue
Posted: Sat Apr 18, 2015 8:42 am 

Replies: 10
Views: 2133


This is helping a lot (signed, unsigned numbers). And I'm getting the concept - if there was some function that took #$10 and subtracted #$20, the result, unsigned, would be #$F0 (#%11110000), and when figuring this as a signed value, that 7th bit would be determinant that this is *negative* (essent...

 Forum: Newbie Help Center   Topic: Wonky compare issue

 Post subject: Re: Wonky compare issue
Posted: Fri Apr 17, 2015 11:37 am 

Replies: 10
Views: 2133


Right. That's probably exactly it. Damn. My brain hurts. haha

 Forum: Newbie Help Center   Topic: Wonky compare issue

 Post subject: Wonky compare issue
Posted: Fri Apr 17, 2015 11:19 am 

Replies: 10
Views: 2133


Alright, so I had a little gremlin...it bugged me enough to just play around in a dummy file. For the life of me, I can't figure out what is going on here. Here's the simple program: Calculation: LDA gamepad AND #PAD_R BEQ notPressingRight LDA number CLC ADC #$01 STA number CMP #$80 BMI keepGoing JM...

 Forum: Newbie Help Center   Topic: Simple table read...

 Post subject: Re: Simple table read...
Posted: Fri Apr 10, 2015 11:24 am 

Replies: 4
Views: 1302


Ugh....disregard this entire thread. I might just delete it. I'm both not crazy and also completely careless. In my testing ground here, I was loading 'test' hex values to the attributes...not at all correlating to what they should have been in binary. There was nothing wrong with my table read, app...

 Forum: Newbie Help Center   Topic: Simple table read...

 Post subject: Re: Simple table read...
Posted: Fri Apr 10, 2015 10:44 am 

Replies: 4
Views: 1302


What's frustrating is it's pretty simple. Just trying to draw to the spriteRam I set up (constant...spriteRam = $0200). I've done this a dozen times or more. There's a table which contains four bytes of tile data followed by four bytes of attribute data. I find the tile data (0-3), write it to sprit...

 Forum: Newbie Help Center   Topic: Simple table read...

 Post subject: Simple table read...
Posted: Fri Apr 10, 2015 10:22 am 

Replies: 4
Views: 1302


Alright, so this should work based on my understanding and other similar examples I have tried. If I have a table that is simply this: DataTable: .db $0A, $0B, $0C, $0D ...and, want to call and store the appropriate value... LDY $02 LDA DataTable,y STA someAddress ...shouldn't the value $0C now be s...

 Forum: Newbie Help Center   Topic: Still grasping indirect addressing...

Posted: Mon Apr 06, 2015 10:02 am 

Replies: 16
Views: 3080


Its more related to other data that will also be packed into each bank relating to those screens specifically. With the method I'm doing now, I could obviously put them in any order so long as the right bank gets loaded upon transition. It's entire possible some arbitrary 'rooms' might also fill out...

 Forum: Newbie Help Center   Topic: Still grasping indirect addressing...

Posted: Mon Apr 06, 2015 8:10 am 

Replies: 16
Views: 3080


Alright, maybe I'll just tweak the method I have rather than making it unnecessarily more difficult than it has to be. The room data will likely not be exactly the same, but the idea is to have it all fit inside of the bank container...so x rooms in bank 0 might take up 75% of the bank space where a...
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