Search found 1588 matches

by Quietust
Wed Sep 30, 2020 6:15 am
Forum: NES Hardware and Flash Equipment
Topic: Simple MMC3 CPLD not working = (( Need your help!
Replies: 10
Views: 333

Re: Simple MMC3 CPLD not working = (( Need your help!

6 bits for each prg bank register can reach 512KB prg-size. but if the prg-rom is not exactly equal to 512KB, so you need another prg_mask[18:14] to cut the high bits of all prg bank registers actually the mapped prg address outputs should be: assign prg_aout[18:13] = {prgsel[5:1] & ~prg_mask[18:14...
by Quietust
Mon Sep 28, 2020 7:20 pm
Forum: NESemdev
Topic: Bad nametable and memory access in Iceclimber
Replies: 6
Views: 313

Re: Bad nametable and memory access in Iceclimber

Disassembling the code in that region reveals that the BIT instruction is actually being used as a 3-byte NOP in order to conditionally execute an LDA #imm instruction: F3BB: A4 00 LDY $00 F3BD: A5 8D LDA $8D F3BF: 29 01 AND #$01 F3C1: D0 03 BNE $F3C6 <-- jumps into the middle of the BIT instruction...
by Quietust
Thu Sep 24, 2020 4:38 pm
Forum: Newbie Help Center
Topic: Sprites are jittery when moving, not moving smoothly
Replies: 13
Views: 445

Re: Sprites are jittery when moving, not moving smoothly

The Rook wrote:
Thu Sep 24, 2020 4:21 pm
Does the second ROM seem better than the first?
For me, the second ROM is worse (1 lag frame every 5 frames), while the first ROM is smooth.
by Quietust
Wed Sep 23, 2020 6:44 pm
Forum: General Stuff
Topic: Help to identify unknown game gun
Replies: 8
Views: 456

Re: Help to identify unknown game gun

It could also be for PC computers. Around mid to late 90s, there were graphic accelerators specifically for games with may include their own jacks for controllers. In particular, there were cards that ran Virtua Fighter, maybe Virtua Cop too, so this gun could be for one of those cards. The only 15...
by Quietust
Tue Sep 22, 2020 4:32 pm
Forum: Newbie Help Center
Topic: Having slow down after only 10 sprites on screen
Replies: 5
Views: 195

Re: Having slow down after only 10 sprites on screen

I suspect that part of the slowdown is from having to index into an array of structures - doing ship.tiles[ i ].x_offset can be very slow when you don't have multiplication instructions, especially if the size of the "ship.tiles" struct isn't a power of 2. You might consider reorganizing those struc...
by Quietust
Mon Sep 21, 2020 5:58 pm
Forum: NESdev
Topic: MMC1 acting differently on PowerPak vs Emulator, not always bankswitching
Replies: 2
Views: 161

Re: MMC1 acting differently on PowerPak vs Emulator, not always bankswitching

frantik wrote:
Mon Sep 21, 2020 5:51 pm
Is it a problem that my rom has 10 banks of CHR? Does it need to be a power of two?
Yes - unless you're using a cartridge that uses multiple ROM chips (on the same bus), the total size must be a power of 2, so I'm guessing that this is your problem.
by Quietust
Mon Sep 21, 2020 4:29 pm
Forum: Newbie Help Center
Topic: .incbin giving me an error
Replies: 11
Views: 294

Re: .incbin giving me an error

I noticed the "smart quotes" in the code sample you pasted, but I wasn't sure if it had been copied verbatim or if it'd been mangled by your web browser: 101 00:C0C4 .incbin “hellomario.chr” Incorrect string syntax! I suppose this probably counts as another " rake ", and it's one I've personally enc...
by Quietust
Mon Sep 21, 2020 4:17 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 566
Views: 229332

Re: Reverse Engineering the CIC

Mmm each time it seems to be a 0X04 that gets changed for a 0x0C, strange. That suggests a bit is getting added or dropped. Maybe I need to tweak the timing a bit. Dump A is the one with "xC", while Dump B has "x4", suggesting that the second one might be the bad one. There's only a few locations w...
by Quietust
Mon Sep 21, 2020 3:51 pm
Forum: Newbie Help Center
Topic: .incbin giving me an error
Replies: 11
Views: 294

Re: .incbin giving me an error

I don’t understand why you are including the CHR file in your entire zeropage... The zeropage starts at $0000 and runs to $0100. I strongly suspect that PRG ROM only occupies banks 0 and 1 and that bank 2 actually corresponds to the PPU's address space, which would be totally normal if NESASM was t...
by Quietust
Mon Sep 21, 2020 3:29 pm
Forum: NESemdev
Topic: Is there a logic to instruction timings?
Replies: 6
Views: 344

Re: Is there a logic to instruction timings?

It doesn’t seem that simple to me... As Dwedit said, lda #n is two cycles; it’s also 2 bytes. lda zpg is three cycles; but also 2 bytes. Oooh, you mean you’d start with 2 cycles and add 1 cycle for the byte fetched from memory. :) Though, you’d have to add another cycle for the high byte used in th...
by Quietust
Sat Sep 19, 2020 7:20 pm
Forum: NESemdev
Topic: VBL Clear time
Replies: 3
Views: 144

Re: VBL Clear time

I am a bit confused about when the VBL flag should be cleared. The wiki page on PPU registers states : cleared after reading $2002 and at dot 1 of the pre-render line. I assume they mean PPU cycle = 1 here. However the page on PPU frame timing states : it's cleared at the start of the pre-render sc...
by Quietust
Fri Sep 18, 2020 6:17 pm
Forum: General Stuff
Topic: How to limit 60 FPS in a loop?
Replies: 8
Views: 368

Re: Emulation refresh rate of 60hz?

If you want to emulate the NTSC NES at exactly 60Hz and have accurate timing, then you'll need to slow the CPU down to 1.78683MHz.
by Quietust
Tue Sep 15, 2020 3:51 pm
Forum: NESdev
Topic: Sprites will not show up
Replies: 12
Views: 509

Re: Sprites will not show up

bit $2002 @loop: bit $2002 bpl @loop lda %10010000 sta $2000 in every known location of running code. its almost laughable at this point, it just won't turn interrupts on no matter what. Is there anything you can think of that I am missing? Thnx for your help, this is so weird You're missing a # si...
by Quietust
Sun Sep 13, 2020 7:09 pm
Forum: NESemdev
Topic: SMB Title does not render on title screen
Replies: 3
Views: 272

Re: SMB Title does not render on title screen

The last 20 or so CHR tiles don't look right - I suspect you're using a pirated version of SMB1 that was hacked to remove the titlescreen logo (and the copyright notice). Incidentally (I'm not sure it's related), I also find it difficult to select 2-players on the title screen. I have to press the s...
by Quietust
Mon Sep 07, 2020 11:02 am
Forum: NESdev
Topic: Questions about NES programming and architecture
Replies: 143
Views: 13422

Re: Questions about NES programming and architecture

NewRisingSun wrote more about that here: https://forums.nesdev.com/viewtopic.php?p=243832#p243832 Indeed, the game in question was Othello by Bit Corp, though it seems the above-mentioned conversation might've happened somewhere else - the old mailing list archive only goes from January 1998 to Mar...