Search found 223 matches

by aquasnake
Mon Apr 05, 2021 11:19 pm
Forum: NES Hardware and Flash Equipment
Topic: Mapper emulation accuracy on N8 PRO
Replies: 1
Views: 303

Re: Mapper emulation accuracy on N8 PRO

At present, FPGA emulation is mostly based on behavior level, rather than circuit netlist and gate level The combinational logic based on signal interconnection is more accurate than the sequential logic based on SRAM look-up and latch, and the sequential logic will add more duplicated/redundant reg...
by aquasnake
Mon Apr 05, 2021 4:15 am
Forum: NES Hardware and Flash Equipment
Topic: Mapper227's multi-menu display
Replies: 12
Views: 3178

Re: Mapper227's multi-menu display

The wiki article says "Bit 11 of the address written activates the menu list selection.", but the bitfield shows the "m" bit, described as "Menu list (see below)", as bit 10 rather than 11. With no public dump of a multi-menu mapper 227 cart available, none of this information can be verified. dip_...
by aquasnake
Sun Apr 04, 2021 8:21 pm
Forum: NES Hardware and Flash Equipment
Topic: Mapper227's multi-menu display
Replies: 12
Views: 3178

Re: Mapper227's multi-menu display

Mapper242 is a subset of mapper227. The difference between them is the power on value of "S". Mapper242 is initialized to BxROM like mode by default. (Write registers at the odd address only??) Mapper227/mapper242 they can be directly compatible if the 16KB granularity page is copied from bank0 to b...
by aquasnake
Sat Apr 03, 2021 5:35 am
Forum: NES Hardware and Flash Equipment
Topic: Mapper227's multi-menu display
Replies: 12
Views: 3178

Re: Mapper227's multi-menu display

CRAM write protection only affects the cart without memory saving function, while Chinese RPG games such as Waixing / Nanjing all have backup batteries, so it can be judged heuristically by identifying the battery flag bit of ines header. These carts only work in 32K mode, and "O = 1" conflicts with...
by aquasnake
Sat Apr 03, 2021 1:28 am
Forum: NES Hardware and Flash Equipment
Topic: Mapper227's multi-menu display
Replies: 12
Views: 3178

Re: Mapper227's multi-menu display

Instead of reading the dip switch, most emulators just set a counter and accumulate after each reset to switch the menu.Or do not emulate this part of logic at all, just display the default menu For single-cart games, they have no menulist, dip switch accessing can be completely ignored Waixing's ma...
by aquasnake
Fri Apr 02, 2021 10:16 pm
Forum: NES Hardware and Flash Equipment
Topic: Mapper227's multi-menu display
Replies: 12
Views: 3178

Re: Mapper227's multi-menu display

To ensure that when reading the dip setting, it is recommended to access $8000 - $BFFF only. If the read address is in the vfixrom segment, it will cause a crash. Another method is to copy the menu loader to xram ($5000 - $5fff) and execute from there, and then read DIP setting from any address of $...
by aquasnake
Fri Apr 02, 2021 10:08 pm
Forum: NES Hardware and Flash Equipment
Topic: Mapper227's multi-menu display
Replies: 12
Views: 3178

Re: Mapper227's multi-menu display

NewRisingSun wrote:
Fri Apr 02, 2021 9:52 am
Which Nanjing game use mapper 227?
Xiang Shuai Chuan Qi (NJxxx) (Ch).nes

Mei Guo Fu Hao (Waixing) (Ch) [a1].nes
by aquasnake
Fri Apr 02, 2021 6:05 am
Forum: NES Hardware and Flash Equipment
Topic: Mapper227's multi-menu display
Replies: 12
Views: 3178

Re: Mapper227's multi-menu display

Banks CPU $5000-$5FFF: 4 KiB extra PRG-RAM, for manu loader use only CPU $6000-$7FFF: 8 KiB unbanked PRG-RAM, battery-backed for Nanjing games CPU $8000-$FFFF: 16/32 KiB switchable PRG-ROM bank PPU $0000-$1FFF: 8 KiB unbanked CHR-RAM Nametable mirroring: mapper setting Registers When reset/power on...
by aquasnake
Mon Mar 22, 2021 8:41 am
Forum: NES Hardware and Flash Equipment
Topic: NES RP2A03 Logic Threshold
Replies: 16
Views: 3132

Re: NES RP2A03 Logic Threshold

HC/LS can be compatible with 5V TTL level, it may need pull up/down resistors to ensure that the logic is not disordered when power on or off. Generally, the weak pull-up/down resistance should be 47K, the strong pull-up/down one is 10K, and the strong pull-up/down resistance can be 4.7K in the cas...
by aquasnake
Sun Mar 21, 2021 10:19 pm
Forum: NES Hardware and Flash Equipment
Topic: NES RP2A03 Logic Threshold
Replies: 16
Views: 3132

Re: NES RP2A03 Logic Threshold

HC/LS can be compatible with 5V TTL level, it may need pull up/down resistors to ensure that the logic is not disordered when power on or off. Generally, the weak pull-up/down resistance should be 47K, the strong pull-up/down one is 10K, and the strong pull-up/down resistance can be 4.7K in the case...
by aquasnake
Wed Mar 17, 2021 5:15 am
Forum: NES Hardware and Flash Equipment
Topic: a databus conflict between OAM DMA and PRG-ROM.
Replies: 4
Views: 1105

Re: a databus conflict between OAM DMA and PRG-ROM.

If I'm understanding right, it sounds like you're talking about the behavior discussed in this thread, which affects the FDS RAM adapter, some flash carts, and some modern carts: Graphical glitches on the Everdrive (page 3) . If you mean something else, please disregard this post. These glitches do...
by aquasnake
Tue Mar 16, 2021 10:29 pm
Forum: NES Hardware and Flash Equipment
Topic: a databus conflict between OAM DMA and PRG-ROM.
Replies: 4
Views: 1105

Re: a databus conflict between OAM DMA and PRG-ROM.

At present, I guess that after setting $4014 in vblank, the databus during φ1 period will be occupied by DMA. If prg-ram is written in vblank interrupt, there will be a certain time overlapping drive between φ1 and φ2 due to the inaccurate M2 timing, which will lead to bus competition. Need to avoid...
by aquasnake
Mon Mar 15, 2021 9:53 pm
Forum: NES Hardware and Flash Equipment
Topic: a databus conflict between OAM DMA and PRG-ROM.
Replies: 4
Views: 1105

a databus conflict between OAM DMA and PRG-ROM.

One theory is that when 6502 is doing OAM DMA, there will be interferences/glitches on the CPU databus. If the external memory is ROM (flash or mask-ROM), there is usually no problem due to the long setup time of ROM accessing. If we use ram instead of ROM (such as ROM emulator device or FDS RAM ada...
by aquasnake
Wed Mar 10, 2021 12:44 am
Forum: NESdev
Topic: NFT/Blockchain ROMS
Replies: 24
Views: 1829

Re: NFT/Blockchain ROMS

For the manufacturing of industrial products, it is not necessary to seek the permission of all customers who have sold before for each product produced again, because producers always want unlimited production. If you make a game product with limited distribution, and then use blockchain technolog...
by aquasnake
Tue Mar 09, 2021 11:48 pm
Forum: NESdev
Topic: NFT/Blockchain ROMS
Replies: 24
Views: 1829

Re: NFT/Blockchain ROMS

For the manufacturing of industrial products, it is not necessary to seek the permission of all customers who have sold before for each product produced again, because producers always want unlimited production. If you make a game product with limited distribution, and then use blockchain technology...