BBK Emulator

// Bank-switched memory bus
// BBK uses flash banking for ROM

pub struct MemoryBus {
    flash: Vec<u8>,       // 2 MiB flash
    ram: [u8; 0x10000],    // 64 KiB RAM
    bank_regs: [u8; 8],    // bank registers
}

impl MemoryBus {
    pub fn read(&self, addr: u16) -> u8 {
        match addr {
            0x0000..=0x3FFF => {
                // Banked ROM region
                let bank = self.bank_regs[...];
                self.flash[bank_offset + addr]
            }
            0x4000..=0x7FFF => self.ram[addr],
            // ... hardware registers
        }
    }
}

// 159×96 monochrome LCD framebuffer
// with ghosting effect simulation

pub struct Lcd {
    buffer: [bool; 159 * 96],
    prev_buffer: [bool; 159 * 96],
    contrast: u8,
}

impl Lcd {
    pub fn set_pixel(&mut self,
        x: usize, y: usize, on: bool
    ) {
        if x < 159 && y < 96 {
            self.buffer[y * 159 + x] = on;
        }
    }

    pub fn render_rgb565(&self,
        out: &mut [u8],
    ) {
        // Green-tinted monochrome
        // LCD ghosting via prev_buffer
    }
}