made mapper module to support the various NES cartridge types in the furyte, MMC1 support added

src/bus.rs

@@ -23,7 +23,7 @@ impl Bus for NesBus {
             0x2000..=0x3FFF => 0, //PPU registers stub, temporal
             0x4000..=0x401F => 0, //APU controller stub, temporal
             0x4020..=0x5FFF => 0, //Expansion ROM stub. temporal
-            0x6000..=0x7FFF => 0, //SRAM stub, no reading saves for you :3
+            0x6000..=0x7FFF => self.cart.read_prg_ram(address), // SRAM reads from the cartridge
             0x8000..=0xFFFF => self.cart.read_prg(address), // this is te space PRG Rom gets "loaded" to in real hardware
         }
     }
@@ -31,6 +31,8 @@ impl Bus for NesBus {
     fn write(&mut self, address: u16, value: u8) {
         match address {
             0x0000..=0x1FFF => self.ram[(address & 0x07FF) as usize] = value,
+            0x6000..=0x7FFF => self.cart.write_prg_ram(address, value),
+            0x8000..=0xFFFF => self.cart.write_prg(address, value),
             _ => {} // Everything else dropped for now
         }
     }