11 March 2016 - Forum Rules
Started by Polinym, November 17, 2019, 01:49:57 AM
QuoteHow do mappers/switching banks work?
LDA #$06STA $8000 ; by writing 6, we're saying we want to configure $8000-9FFF slot ; if we wrote 7, we'd be configuring the $A000-BFFF slotLDA #$03STA $8001 ; This will put page 3 (ROM offset $06010) into the $8000-9FFF slotLDA $8010 ; reads from .nes file offset $06020 ... $10 bytes into page 3
Quote from: Cyneprepou4uk on November 17, 2019, 03:57:14 PMLike I said before, sram in fceux works without that register.
4E 45 53 1A 08 08 40 00 00 ... original4E 45 53 1A 08 08 42 00 00 ... new ^ | This is all you change
QuoteAny tips on how to find a good JMP routine to change to reroute to new SRAM-saving code?
QuoteAlso, I tried adding code to Pop Star Debut from a JSR that wrote #80 to $A001, set A to whatever I skipped, then JSR'd to the original address
Quote from: Disch on November 18, 2019, 12:43:01 AMI know Cynepropou4k is telling you not to worry about $A001, but I strongly disagree with that advice.
Quote from: KingMike on November 18, 2019, 02:12:07 AMAs I understand there are variations of MMC3 (and the Namco and Tengen mappers are related in that I THINK it was Namco that made the first variants and then they licensed it out to Tengen and Nintendo, or something like that), in that some supported SRAM, some did not, and with SRAM some had an enable switch and some always enabled).
Quoteemulators should error on the side of compatibility (allow SRAM unless disabled by code), while writing code should error on the side of being precise (enable and disable SRAM as needed)?
Quote from: Disch on November 18, 2019, 12:43:01 AMThat header is... not right. You're changing the mapper from a standard MMC3 (mapper 4) to .... mapper 206? Some weird Tengen/Namco mapper that mimics an MMC3? No wonder you're having issues. Aside from not having on-board PRG RAM, mapper 206 doesn't control mirroring or have IRQs, so I can't imagine this would work.
Quote from: Supper on November 18, 2019, 11:02:00 AMSee this topic involving the mentioned problem with glitched graphics. The short version is that this game (LaSalle Ishii no Childs Quest) depends on having the correct hardwired nametable mirroring setup, and as it does in fact use mapper 206, I recommended changing both the header's mapper number and nametable mirroring bit to reflect the correct values for the cartridge.
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