Fix SRAM addressable range

src/emulator/cart.rs

@@ -28,14 +28,14 @@ impl Cart {
 
         let sram = if sram_file.metadata()?.len() == 0 {
             // new SRAM file, randomize the contents
-            let mut sram = vec![0; 8 * 1024];
+            let mut sram = vec![0; 16 * 1024];
             let mut rng = rand::rng();
             for dst in sram.iter_mut().step_by(2) {
                 *dst = rng.random();
             }
             sram
         } else {
-            let mut sram = Vec::with_capacity(8 * 1024);
+            let mut sram = Vec::with_capacity(16 * 1024);
             sram_file.read_to_end(&mut sram)?;
             sram
         };