Slight optimizations, more centered center

src/main/java/net/brokenmoon/BasicMonitorDriver.java

@@ -13,6 +13,7 @@ import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.IOException;
 import java.net.URISyntaxException;
+import java.util.Arrays;
 import java.util.Objects;
 
 import static com.simon816.j65el02.device.RPMonitor.HEIGHT;
@@ -21,15 +22,12 @@ import static com.simon816.j65el02.device.RPMonitor.WIDTH;
 public class BasicMonitorDriver implements MonitorDriver, KeyListener {
 
     BufferedImage display;
-    final int width = 8;
-    final int height = 8;
-    int rows = 16;
-    int cols = 16;
     JLabel[] lines = new JLabel[HEIGHT];
     Machine emu;
+    byte[][] windowDataOld = new byte[HEIGHT][WIDTH];
 
-    int xoffset = 32;
-    int yoffset = 27;
+    int xoffset = 30;
+    int yoffset = 26;
     public BasicMonitorDriver(Machine emu) {
         this.emu = emu;
         try{
@@ -102,11 +100,14 @@ public class BasicMonitorDriver implements MonitorDriver, KeyListener {
     public void update(byte[][] windowData) {
         for(int y = windowData.length - 1; y >= 0; y--){
             String text = "";
-            for(int x = 0; x<windowData[y].length; x++){
-                int temp = Math.floorMod(windowData[y][x] , 256);
-                text += (char)((temp + 0xDED0));
+            if(!Arrays.equals(windowData[y], windowDataOld[y])) {
+                for (int x = 0; x < windowData[y].length; x++) {
+                    int temp = Math.floorMod(windowData[y][x], 256);
+                    text += (char) ((temp + 0xDED0));
+                }
+                lines[y].setText(text);
+                System.arraycopy(windowData[y], 0, windowDataOld[y], 0, windowData[y].length);
             }
-            lines[y].setText(text);
         }
     }