Search found 22119 matches

by tepples
Sun Dec 26, 2004 9:35 pm
Forum: General Stuff
Topic: anyone seen that nintendo joysitck/gun??
Replies: 14
Views: 12693

Today I saw one in the mall for $50 that actually takes Famicom cartridges and is sold with an apparently dupe-free 111-in-1 Famicom cartridge. And no, it doesn't have screwed up audio waveforms like a previous one sold in the mall had. But to maintain a good relationship with Nintendo, I don't fina...
by tepples
Sat Dec 25, 2004 2:38 pm
Forum: NESemdev
Topic: Mario Sprites Problem
Replies: 9
Views: 11852

You can make SBC always work by implementing SBC in terms of ADC: load the operand from memory as normal, invert it (^ 0xff), and then do your ADC code. Reducing complexity of your emulator's 6502 core is a good thing.
by tepples
Fri Dec 24, 2004 10:16 pm
Forum: NESemdev
Topic: PPU emulation
Replies: 11
Views: 11129

A tile is divided into two 8-byte bitplanes, each of which is divided into eight 1-byte rows. Each row has 8 pixels; the most significant bit of each row is drawn on the left (except in horizontally flipped sprites). Thus, each pixel corresponds to a bit in the first plane and a bit in the second pl...
by tepples
Thu Dec 23, 2004 10:58 pm
Forum: NESemdev
Topic: line 0 sprite throw away
Replies: 6
Views: 7170

Sixteen pixels, all well within the overscan on NTSC and barely noticeable on PAL, so who gives a sh**, turning the screen on late means MORE VBLANK TIME FOR MEEEEEE!!!!!111

(sorry, couldn't resist)
by tepples
Thu Dec 23, 2004 6:15 pm
Forum: NESemdev
Topic: line 0 sprite throw away
Replies: 6
Views: 7170

If you set a sprite's Y coordinate to 0, it'll be drawn on lines 1 through 8 or 1 through 16 depending on the sprite height switch. So I thought the garbage line for computing sprite priority was the first line of the actual screen, because a sprite can't start on line 0, right? Or does the PPU take...
by tepples
Thu Dec 23, 2004 12:16 am
Forum: Newbie Help Center
Topic: So, how does the NES access all that memory?
Replies: 5
Views: 6469

Mappers.

The cart places writable registers somewhere in the $4018-$FFFF range, and these registers control the upper address lines of the program and graphics ROMs, effectively "turning the page" so to speak. The easiest to understand are UNROM/UOROM (iNES mapper #2) and CNROM (iNES mapper #3).
by tepples
Thu Dec 23, 2004 12:13 am
Forum: NESdev
Topic: Looking for an old palette...
Replies: 7
Views: 6120

I used to use Rew too, but in late 2001 I dropped it in favor of a GBC emulator called VisualBoy, which eventually became a GBC/GBA emulator called VisualBoyAdvance. Now FCE Ultra and VBA are my first-line emulators, and I try every NES program I make on FCEU and Nintendulator before letting anyone ...
by tepples
Tue Dec 21, 2004 12:20 am
Forum: NES Hardware and Flash Equipment
Topic: $4014 DMA Data Tranfer
Replies: 10
Views: 10324

If the CPU and a cart are giving two different signals to the same input, I have no idea what would happen. Any idea how I could force it? Preferably without frying something. :) I suspect it's like data bus contention on a CNROM or UNROM. My cart uses CHR-RAM, it's the same chip for the nametables...
by tepples
Mon Dec 20, 2004 5:23 pm
Forum: NESemdev
Topic: Bandlimited waveforms algorithm?
Replies: 15
Views: 26084

TimW wrote:sllightly better then linear interpolation with out the over head of fir would be a weighed guassian with it's center at the center of the sample period
That is FIR. FIR and convolution are the same thing. Or are you describing some sort of IIR filter with a roughly Gaussian impulse response?
by tepples
Mon Dec 20, 2004 5:14 pm
Forum: NES Hardware and Flash Equipment
Topic: $4014 DMA Data Tranfer
Replies: 10
Views: 10324

The lines that choose a PPU register are CPU A0 through A2; PPU A0 through A2 go to VROM and VRAM. Has anybody tried making a cart that can force CPU A2-A0 high during PPU access (CPU A15-A13 = 001)? I think updating OAM through 'sta $2004' is error prone because 1. there's not enough vblank time to...
by tepples
Sun Dec 19, 2004 8:46 pm
Forum: Newbie Help Center
Topic: Super Mario Bros. and Duck Hunt Font?
Replies: 15
Views: 26486

Yeah, any Helvetica-clone font should do if you're trying to do a trade-dress-based satire of the early NES library's cart labels.
by tepples
Sat Dec 18, 2004 12:22 am
Forum: Newbie Help Center
Topic: Super Mario Bros. and Duck Hunt Font?
Replies: 15
Views: 26486

Also, not a whole lot of games have a lowercase, but that's understandable. In JQ, I just use 100% standard Ascii order, and it fits exactly as a 2K bank 2 KB? That's half your tilespace gone right there. And that is why JQ has a lowercase. :P Oh, and it's cool because I can just type text into the...
by tepples
Fri Dec 17, 2004 2:07 am
Forum: Newbie Help Center
Topic: Super Mario Bros. and Duck Hunt Font?
Replies: 15
Views: 26486

Not necessarily. I've been collecting 8x8 pixel fonts, and though the ones in Super Mario Bros., Tetris (Tengen), Tetris (Nintendo), and Lode Runner look rather similar, the one in the Mega Man series looks somewhat different, and the one used in Tetris for Game Boy is totally different. http://pics...
by tepples
Wed Dec 15, 2004 11:45 pm
Forum: NES Music
Topic: Festalon
Replies: 6
Views: 9702

How would one play multiple-chip music on a real Famicom? If it involves soldering a custom cart together, then I might as well solder a serial port interface onto a Famicom board, hook it up to a CD player, and then call MP3s NSFs :P
by tepples
Wed Dec 15, 2004 4:05 pm
Forum: NESdev
Topic: OAM and palette decay
Replies: 7
Views: 6299

Thanks. I ought to make a demo for measuring how long the PPU's internal OAM and palette RAM maintain their contents during forced blank (lda #0 sta $2001). Are there any special considerations for preparing a ROM to run on Squeedo, other than that it uses CHR RAM and 4-screen mirroring?