Enum Mmc3Variant 

pub enum Mmc3Variant {
    Standard,
    Mmc6,
    HardwiredMirroring,
    McAcc,
}

Which chip or board wiring an Mmc3 models, beyond the IRQ revision (the NES 2.0 submappers of mapper 4, NES_2_0_submappers.md). v2.9.6.

Variants

Standard

A standard MMC3 board (submappers 0 and 4).

Mmc6

Submapper 1, the MMC6 (MMC6.md): 1 KiB of internal PRG-RAM at $7000-$7FFF, enabled by $8000 bit 5, with separate read and write enables for each 512-byte half in $A001 bits 4-7.

HardwiredMirroring

Submapper 2: an MMC3C with hard-wired mirroring; $A000 does nothing.

McAcc

Submapper 3, Acclaim’s MC-ACC (MMC3.md, “IRQ Specifics”): the scanline counter is clocked by FALLING edges of PPU A12 through a divide-by-8 prescaler instead of the M2 filter. The page gives only that. The two details used here come from the forum measurement it links (forums.nesdev.org, p=242427): writing $C001 resets the prescaler, and the counter clocks on the first edge of each group of eight. That evidence is forum-level, so mapper 4 submapper 3 is BestEffort in tier.rs.

Trait Implementations

impl Clone for Mmc3Variant

fn clone(&self) -> Mmc3Variant

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Mmc3Variant

impl Debug for Mmc3Variant

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Mmc3Variant

fn default() -> Mmc3Variant

Returns the “default value” for a type.

impl Eq for Mmc3Variant

impl PartialEq for Mmc3Variant

fn eq(&self, other: &Mmc3Variant) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Mmc3Variant