diff --git a/cpu.js b/cpu.js
index eef820f..012594b 100644
--- a/cpu.js
+++ b/cpu.js
@@ -124,7 +124,8 @@ function CPU_65816() {
                       0x7e : ROR_absolute_indexed_x,
                       0x76 : ROR_direct_page_indexed_x,
                       0x48 : PHA , 0x68 : PLA, 0x5a : PHY, 0x7a : PLY,
-                      0xda : PHX, 0xfa : PLX, 0x08 : PHP, 0x28 : PLP };
+                      0xda : PHX, 0xfa : PLX, 0x08 : PHP, 0x28 : PLP, 
+                      0xf4 : PEA, 0xd4 : PEI };
 
   /**
    * Take a raw hex string representing the program and execute it.
@@ -203,6 +204,29 @@ var MMU = {
   }
 };
 
+var PEA = {
+  bytes_required:function() {
+    return 3;
+  },
+  execute:function(cpu, bytes) {
+    cpu.mmu.store_byte(cpu.r.s--, bytes[0]);
+    cpu.mmu.store_byte(cpu.r.s--, bytes[1]);    
+  }
+};
+
+var PEI = {
+  bytes_required:function() {
+    return 2;
+  },
+  execute:function(cpu, bytes) {
+    var location = bytes[0]+cpu.r.d;
+    var low_byte = cpu.mmu.read_byte(location);
+    var high_byte = cpu.mmu.read_byte(location+1);
+    cpu.mmu.store_byte(cpu.r.s--, high_byte);
+    cpu.mmu.store_byte(cpu.r.s--, low_byte); 
+  }
+};
+
 var PHP = {
   bytes_required:function() {
     return 1;
@@ -244,7 +268,7 @@ var PHX = {
       var low_byte = cpu.r.x & 0x00ff;
       var high_byte = cpu.r.x >> 8;
       cpu.mmu.store_byte(cpu.r.s--, high_byte);
-      cpu.mmu.store_byte(cpu.r.s--, high_byte);
+      cpu.mmu.store_byte(cpu.r.s--, low_byte);
     }
   }
 };
@@ -283,7 +307,7 @@ var PHY = {
       var low_byte = cpu.r.y & 0x00ff;
       var high_byte = cpu.r.y >> 8;
       cpu.mmu.store_byte(cpu.r.s--, high_byte);
-      cpu.mmu.store_byte(cpu.r.s--, high_byte);
+      cpu.mmu.store_byte(cpu.r.s--, low_byte);
     }
   }
 };