Search found 10705 matches

by lidnariq
Thu Jan 20, 2022 1:33 pm
Forum: NESdev
Topic: Initial state of PRGbanks with MMC1?
Replies: 6
Views: 155

Re: Initial state of PRGbanks with MMC1?

Nintendo's leaked MMC1 datasheet says that the banks are unknown on powerup. We've had people both report random power-up banks and reliable power-up banks. Several games include multiple reset vectors, not relying on any one memory layout being reliable enough. Lots of commercial games do not succe...
by lidnariq
Thu Jan 20, 2022 12:13 pm
Forum: Reproduction
Topic: Microcontroller for switching address pins LoROM and HiROM
Replies: 1
Views: 73

Re: Microcontroller for switching address pins LoROM and HiROM

No microcontroller, no. Ordinary 74xx series multiplexers can work, however.
by lidnariq
Wed Jan 19, 2022 12:38 pm
Forum: Newbie Help Center
Topic: Question about writing to internal PPU cgram mid frame (involving overriding the bus in the cartridge))
Replies: 1
Views: 76

Re: Question about writing to internal PPU cgram mid frame (involving overriding the bus in the cartridge))

The PPU internally synchronizes things on pixel edges (it uses two biphase clocks at 5.4MHz) so you can't "just" override M2 and call it a day. Unfortunately, the PPU treats CGRAM and "normal" PPU RAM writes almost the same way, so there's still a large delay of 6-9-ish pixels af...
by lidnariq
Sun Jan 16, 2022 11:20 am
Forum: NESdev
Topic: Early Hong Kong Micro Genius version with unusual encoder
Replies: 7
Views: 375

Re: Early Hong Kong Micro Genius version with unusual encoder

Definitely! The MK5060 appears to be what's responsible for pausing the PPU after the visible field is drawn... I guess it has to move the vertical sync too.
by lidnariq
Sat Jan 15, 2022 4:36 pm
Forum: General Stuff
Topic: nes-cpu-01 mainboard
Replies: 3
Views: 135

Re: nes-cpu-01 mainboard

Those green jumpers are stock, correcting for a design flaw.
by lidnariq
Sat Jan 15, 2022 11:47 am
Forum: General Stuff
Topic: nes-cpu-01 mainboard
Replies: 3
Views: 135

Re: nes-cpu-01 mainboard

Redherring recently managed to borrow and reverse-engineer the differences in the rev 1 and 2 NES mainboards. In his github: https://github.com/Redherring32/OpenTen ... -01_02.pdf

As far as scarcity: the first, and quite rare. As far as that being interesting? Not at all.
by lidnariq
Fri Jan 14, 2022 12:44 pm
Forum: Other Retro Dev
Topic: DOS VGA Tricks
Replies: 51
Views: 24165

Re: DOS VGA Tricks

According to VGA.TXT, you should be able to get fine X scrolls from 0 to 3 by writing 0/2/4/6 to 3c0h/13h, not 4...
by lidnariq
Thu Jan 13, 2022 5:01 pm
Forum: NESemdev
Topic: Count Errors Test ROM and some new DMC glitch info
Replies: 56
Views: 2633

Re: Count Errors Test ROM and some new DMC glitch info

Relatedly, here is the tiny test ROM that Fiskbit specified to record bus activity of: ;;; public domain (fiskbit+lidnariq 2022) ;;; assemble with cl65 -t none -o colliding-dma.bin colliding-dma.asm .setcpu "6502x" .CODE .org $E000 .include "constants.ca65.inc" reset: lda #$0F st...
by lidnariq
Thu Jan 13, 2022 4:55 pm
Forum: NESemdev
Topic: Count Errors Test ROM and some new DMC glitch info
Replies: 56
Views: 2633

Re: Count Errors Test ROM and some new DMC glitch info

On the NES, the controller ports are directly connected to the CPU - the signal is true for the entire time that the address bus is stable, and φ0/φ2/M2 aren't a factor. On the Famicom, the same signal is instead shaped by M2 - the joypads' CLOCK inputs are connected to the 40H368 that drives NOT(M2...
by lidnariq
Thu Jan 13, 2022 11:46 am
Forum: NES Hardware and Flash Equipment
Topic: Help to program 16 bit EPROMs on a 8 bit programmer
Replies: 5
Views: 310

Re: Help to program 16 bit EPROMs on a 8 bit programmer

Maybe the multiplexers I'm using, 74HC257 aren't bi-directional, are they? Correct. Does such multiplex exist? Yes, an analog multiplexer such as the 74'3257, 4053, or 4551. Should I add a 78L05 to the VPP pin to select the direction or there's some better way to do it? Normal voltage regulators wo...
by lidnariq
Wed Jan 12, 2022 1:24 pm
Forum: Other Retro Dev
Topic: DOS VGA Tricks
Replies: 51
Views: 24165

Re: DOS VGA Tricks

I wouldn't have expected 3d4/C and D to have worked - after all, there'd be less point in 3d4/18h if so. But it does sound like, based on what you're saying, that 3c0/13h is working... if not particularly interesting.
by lidnariq
Wed Jan 12, 2022 10:39 am
Forum: Other Retro Dev
Topic: DOS VGA Tricks
Replies: 51
Views: 24165

Re: DOS VGA Tricks

I have a real VGA to test, I might try later. EDIT: This is not going to work, documentation says it is used to calculate the start address at the top left of the screen, and it adds this to the start address register. start address registers are only updated once per frame :(. That feels weird to ...
by lidnariq
Tue Jan 11, 2022 10:32 pm
Forum: phpBB Issues
Topic: Animations (such as 'new post glow') eat up CPU/GPU resources
Replies: 4
Views: 261

Re: Animations (such as 'new post glow') eat up CPU/GPU resources

The only other ones I saw were in font-awesome.min.css (ugh)

has .fa-spin and .fa-pulse animations
by lidnariq
Tue Jan 11, 2022 11:10 am
Forum: Other Retro Dev
Topic: DOS VGA Tricks
Replies: 51
Views: 24165

Re: DOS VGA Tricks

On that copper demo, they use a rare VGA card which lets you change start address every scan line, but very few VGA cards and monitors will cope with that. Copper by Surprise! doesn't do that - VGA registers don't provide any interface to that. At best, it might be possible to update the fine X scr...
by lidnariq
Mon Jan 10, 2022 7:56 pm
Forum: NES Hardware and Flash Equipment
Topic: Need advice buying a NES-101 and a flash cart
Replies: 39
Views: 1199

Re: Need advice buying a NES-101 and a flash cart

Looks fine, but I can't figure out the "why" part...