Enum ConsoleModel 

pub enum ConsoleModel {
    Nes,
    Famicom,
}

v2.9.8 — which console wires the PPU’s /RESET line.

The 2C02 is the same chip in every NTSC console; what differs is the board around it. The NESdev “PPU power up state” page (§Famicom, and its closing note on front- and top-loaders) documents two wirings:

• NES (front-loader, NES-001) — the CPU and PPU are reset together. At power-on and on every press of Reset the PPU spends about 29,658 CPU cycles (NTSC) in its warm-up state, ignoring writes to $2000, $2001, $2005 and $2006, and Reset clears PPUCTRL, PPUMASK, the scroll/address latch and the read buffer.
• Famicom — the PPU’s /RESET is tied to 5 V and only the CPU’s rides a 0.47 µF capacitor. At power-on the PPU therefore starts initialising roughly one frame before the CPU leaves reset, which is longer than the warm-up window, so the CPU’s first instructions can already write the masked registers. The Reset button reaches only the CPU: the PPU keeps running and keeps its register state.

What this models, and what it does not:

• Power-on under Self::Famicom closes the warm-up window before the first instruction (rustynes_ppu::Ppu::end_warmup). NESdev gives the lead as “approximately one frame … the exact timing has not been measured, and may vary”, so the PPU’s frame position is left where the NES model puts it rather than advanced by a guessed amount.
• A warm reset under Self::Famicom leaves the PPU untouched. The APU, DMA unit and cartridge reset exactly as under Self::Nes.
• The NES-101 top-loader shares the Famicom’s reset wiring, but NESdev does not document its power-on lead, so it is not offered as a separate model.

Off by default. Self::Nes is the model every release before v2.9.8 emulated, so the default build is byte-identical. The selection is a host/config knob, never derived from the ROM: NES 2.0 has no console type that distinguishes a Famicom from an NES, and the project does not guess a console from a per-game list. It is not part of the save-state (the warm-up counter it acts on already is), and like the other hardware knobs on Nes it is re-applied by the host after a load or power-cycle.

Variants

Nes

Default. Front-loading NES: the CPU and PPU share the reset line.

Famicom

Famicom: the PPU is never held in reset, so it leaves its warm-up before the CPU starts and ignores the Reset button.

Trait Implementations

impl Clone for ConsoleModel

fn clone(&self) -> ConsoleModel

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ConsoleModel

impl Debug for ConsoleModel

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

Formats the value using the given formatter.

impl Default for ConsoleModel

fn default() -> ConsoleModel

Returns the “default value” for a type.

impl Eq for ConsoleModel

impl Hash for ConsoleModel

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ConsoleModel

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ConsoleModel