NESBank now has a getBase64() method that can get the base64 string of the bank at any size without interrupting the access_mode and access_offset settings. Also now has a eq() method which will return true if the given object is a NESBank containing the same data.

app/js/models/NESBank.js

   }
 
   get base64(){
-    var b = "";
-    var data = this.chr;
-    for (var i = 0; i < data.length; i++) {
-      b += String.fromCharCode(data[i]);
-    }
-    return window.btoa(b);
+    return this.getBase64(this.__AccessMode, this.__AccessOffset);
+    //var b = "";
+    //var data = this.chr;
+    //for (var i = 0; i < data.length; i++) {
+    //  b += String.fromCharCode(data[i]);
+    //}
+    //return window.btoa(b);
   }
 
   set base64(s){
   }
 
 
+  getBase64(mode, offset){
+    var b = "";
+    var data = this.getCHR(mode, offset);
+    for (var i = 0; i < data.length; i++) {
+      b += String.fromCharCode(data[i]);
+    }
+    return window.btoa(b);
+  }
+
   getCHR(mode, offset){
     this.__emitsEnabled = false;
     var oam = this.access_mode;
     comp(this.__RP, 256, ignoreTileZero);
     return this;
   }
+
+  eq(b){
+    if (b instanceof NESBank){
+      if (this.getBase64(NESBank.ACCESSMODE_8K, 0) === b.getBase64(NESBank.ACCESSMODE_8K, 0))
+        return true;
+    }
+    return false;
+  }
 }