From 1981863df90d36019f6887391bd4d782de13acfb Mon Sep 17 00:00:00 2001
From: Bailey Parker <b@ileyparker.com>
Date: Sat, 14 Mar 2015 13:19:07 -0400
Subject: [PATCH 1/2] Color coded monitor for code, PC, read/write, special
 locations, and display

---
 simulator/assembler.js | 386 +++++++++++++++++++++++++++--------------
 simulator/style.css    |  28 +++
 2 files changed, 286 insertions(+), 128 deletions(-)

diff --git a/simulator/assembler.js b/simulator/assembler.js
index b6b9c8e..33f4a49 100644
--- a/simulator/assembler.js
+++ b/simulator/assembler.js
@@ -197,37 +197,70 @@ function SimulatorWidget(node) {
     }
 
     function updatePixel(addr) {
-      ctx.fillStyle = palette[memory.get(addr) & 0x0f];
+      ctx.fillStyle = getPixelColor(addr);
       var y = Math.floor((addr - 0x200) / 32);
       var x = (addr - 0x200) % 32;
       ctx.fillRect(x * pixelSize, y * pixelSize, pixelSize, pixelSize);
     }
 
+    function getPixelColor(addr) {
+
+      return palette[memory.get(addr) & 0x0f];
+    }
+
     return {
       initialize: initialize,
       reset: reset,
-      updatePixel: updatePixel
+      updatePixel: updatePixel,
+      getPixelColor: getPixelColor
     };
   }
 
   function Memory() {
-    var memArray = new Array(0x600);
+    var memArray = new Array(0x600),
+        lastAccessAddress = null,
+        lastAccessIsRead = false;
+
+    function set(addr, val, forProgram) {
+
+      // Flag set if memory is accessed by program
+      // used to indicate which memory locations instructions
+      // are setting in the monitor
+      if(typeof forProgram !== 'undefined' && forProgram) {
+
+        lastAccessAddress = addr;
+        lastAccessIsRead = false;
+      }
 
-    function set(addr, val) {
       return memArray[addr] = val;
     }
 
-    function get(addr) {
+    function get(addr, forProgram) {
+
+      // Flag set if memory is accessed by program
+      // used to indicate which memory locations instructions
+      // are getting in the monitor
+      if(typeof forProgram !== 'undefined' && forProgram) {
+
+        lastAccessAddress = addr;
+        lastAccessIsRead = true;
+      }
+
       return memArray[addr];
     }
 
+    function clearLastAccess() {
+
+      lastAccessAddress = null;
+    }
+
     function getWord(addr) {
       return get(addr) + (get(addr + 1) << 8);
     }
 
     // Poke a byte, don't touch any registers
-    function storeByte(addr, value) {
-      set(addr, value & 0xff);
+    function storeByte(addr, value, forProgram) {
+      set(addr, value & 0xff, forProgram);
       if ((addr >= 0x200) && (addr <= 0x5ff)) {
         display.updatePixel(addr);
       }
@@ -240,26 +273,97 @@ function SimulatorWidget(node) {
     }
 
     function format(start, length) {
-      var html = '';
-      var n;
+      var html = '',
+          inCode = false;
 
       for (var x = 0; x < length; x++) {
         if ((x & 15) === 0) {
           if (x > 0) { html += "\n"; }
-          n = (start + x);
-          html += num2hex(((n >> 8) & 0xff));
-          html += num2hex((n & 0xff));
-          html += ": ";
+          html += addr2hex(start + x) + ": ";
+        }
+
+        if(assembler.isCodeAddress(start + x) && !inCode) {
+
+          html += '<span class="monitor-code">';
+          inCode = true;
+        }
+
+        html += formatByte(start + x);
+
+        if((x % 16) === 15) {
+
+          if(inCode) {
+
+            html += '</span>';
+            inCode = false;
+          }
+
+        } else {
+
+          if(inCode && !assembler.isCodeAddress(start + x + 1)) {
+
+            html += '</span>';
+            inCode = false;
+          }
+
+          html += " ";
         }
-        html += num2hex(memory.get(start + x));
-        html += " ";
       }
+
       return html;
     }
 
+    function formatByte(addr) {
+
+      var hex = num2hex(memory.get(addr)),
+          title = 'title="$' + addr2hex(addr) + '"';
+
+      if(0x0200 <= addr && addr <= 0x05ff) {
+        var rgba = toTransparentRGBA(display.getPixelColor(addr));
+
+        return '<span style="background:' + rgba + ';" ' + title + '>' + hex + '</span>'
+      }
+
+      var classes = '';
+
+      if(addr === lastAccessAddress) {
+
+        classes = lastAccessIsRead ? 'monitor-read ' : 'monitor-write ';
+      }
+
+      if(addr === 0x00fe) {
+
+        classes += 'monitor-random ';
+      }
+
+      if(addr === 0x00ff) {
+
+        classes += 'monitor-lastkey ';
+      }
+
+      if(addr === simulator.getCurrentPC()) {
+
+        classes += 'monitor-pc';
+      }
+
+      return '<span class="' + classes + '" ' + title + '>' + hex + '</span>';
+    }
+
+    function toTransparentRGBA(hex) {
+
+      var r = parseInt(hex.substr(1, 2), 16),
+          g = parseInt(hex.substr(3, 2), 16),
+          b = parseInt(hex.substr(5, 2), 16);
+
+      var opacity = (r != 0 && g != 0 && b != 0) ? '.85' : '.15';
+
+      return 'rgba(' + r + ', ' + g + ', ' + b + ', ' + opacity + ')';
+    }
+
     return {
       set: set,
       get: get,
+      clearLastAccess: clearLastAccess,
       getWord: getWord,
       storeByte: storeByte,
       storeKeypress: storeKeypress,
@@ -360,18 +464,18 @@ function SimulatorWidget(node) {
     }
 
     function DEC(addr) {
-      var value = memory.get(addr);
+      var value = memory.get(addr, true);
       value--;
       value &= 0xff;
-      memory.storeByte(addr, value);
+      memory.storeByte(addr, value, true);
       setNVflags(value);
     }
 
     function INC(addr) {
-      var value = memory.get(addr);
+      var value = memory.get(addr, true);
       value++;
       value &= 0xff;
-      memory.storeByte(addr, value);
+      memory.storeByte(addr, value, true);
       setNVflags(value);
     }
 
@@ -499,23 +603,23 @@ function SimulatorWidget(node) {
       i01: function () {
         var zp = (popByte() + regX) & 0xff;
         var addr = memory.getWord(zp);
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA |= value;
         ORA();
       },
 
       i05: function () {
         var zp = popByte();
-        regA |= memory.get(zp);
+        regA |= memory.get(zp, true);
         ORA();
       },
 
       i06: function () {
         var zp = popByte();
-        var value = memory.get(zp);
+        var value = memory.get(zp, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
-        memory.storeByte(zp, value);
+        memory.storeByte(zp, value, true);
         ASL(value);
       },
 
@@ -536,16 +640,16 @@ function SimulatorWidget(node) {
       },
 
       i0d: function () {
-        regA |= memory.get(popWord());
+        regA |= memory.get(popWord(), true);
         ORA();
       },
 
       i0e: function () {
         var addr = popWord();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ASL(value);
       },
 
@@ -558,22 +662,22 @@ function SimulatorWidget(node) {
       i11: function () {
         var zp = popByte();
         var value = memory.getWord(zp) + regY;
-        regA |= memory.get(value);
+        regA |= memory.get(value, true);
         ORA();
       },
 
       i15: function () {
         var addr = (popByte() + regX) & 0xff;
-        regA |= memory.get(addr);
+        regA |= memory.get(addr, true);
         ORA();
       },
 
       i16: function () {
         var addr = (popByte() + regX) & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ASL(value);
       },
 
@@ -583,22 +687,22 @@ function SimulatorWidget(node) {
 
       i19: function () {
         var addr = popWord() + regY;
-        regA |= memory.get(addr);
+        regA |= memory.get(addr, true);
         ORA();
       },
 
       i1d: function () {
         var addr = popWord() + regX;
-        regA |= memory.get(addr);
+        regA |= memory.get(addr, true);
         ORA();
       },
 
       i1e: function () {
         var addr = popWord() + regX;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ASL(value);
       },
 
@@ -614,7 +718,7 @@ function SimulatorWidget(node) {
       i21: function () {
         var zp = (popByte() + regX) & 0xff;
         var addr = memory.getWord(zp);
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA &= value;
         AND();
       },
@@ -634,11 +738,11 @@ function SimulatorWidget(node) {
       i26: function () {
         var sf = carrySet();
         var addr = popByte();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
         value |= sf;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROL(value);
       },
 
@@ -661,12 +765,12 @@ function SimulatorWidget(node) {
       },
 
       i2c: function () {
-        var value = memory.get(popWord());
+        var value = memory.get(popWord(), true);
         BIT(value);
       },
 
       i2d: function () {
-        var value = memory.get(popWord());
+        var value = memory.get(popWord(), true);
         regA &= value;
         AND();
       },
@@ -674,11 +778,11 @@ function SimulatorWidget(node) {
       i2e: function () {
         var sf = carrySet();
         var addr = popWord();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
         value |= sf;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROL(value);
       },
 
@@ -691,24 +795,24 @@ function SimulatorWidget(node) {
       i31: function () {
         var zp = popByte();
         var value = memory.getWord(zp) + regY;
-        regA &= memory.get(value);
+        regA &= memory.get(value, true);
         AND();
       },
 
       i35: function () {
         var addr = (popByte() + regX) & 0xff;
-        regA &= memory.get(addr);
+        regA &= memory.get(addr, true);
         AND();
       },
 
       i36: function () {
         var sf = carrySet();
         var addr = (popByte() + regX) & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
         value |= sf;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROL(value);
       },
 
@@ -718,14 +822,14 @@ function SimulatorWidget(node) {
 
       i39: function () {
         var addr = popWord() + regY;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA &= value;
         AND();
       },
 
       i3d: function () {
         var addr = popWord() + regX;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA &= value;
         AND();
       },
@@ -733,11 +837,11 @@ function SimulatorWidget(node) {
       i3e: function () {
         var sf = carrySet();
         var addr = popWord() + regX;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit7(value);
         value = value << 1;
         value |= sf;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROL(value);
       },
 
@@ -750,23 +854,23 @@ function SimulatorWidget(node) {
       i41: function () {
         var zp = (popByte() + regX) & 0xff;
         var value = memory.getWord(zp);
-        regA ^= memory.get(value);
+        regA ^= memory.get(value, true);
         EOR();
       },
 
       i45: function () {
         var addr = popByte() & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA ^= value;
         EOR();
       },
 
       i46: function () {
         var addr = popByte() & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         LSR(value);
       },
 
@@ -793,17 +897,17 @@ function SimulatorWidget(node) {
 
       i4d: function () {
         var addr = popWord();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA ^= value;
         EOR();
       },
 
       i4e: function () {
         var addr = popWord();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         LSR(value);
       },
 
@@ -816,22 +920,22 @@ function SimulatorWidget(node) {
       i51: function () {
         var zp = popByte();
         var value = memory.getWord(zp) + regY;
-        regA ^= memory.get(value);
+        regA ^= memory.get(value, true);
         EOR();
       },
 
       i55: function () {
         var addr = (popByte() + regX) & 0xff;
-        regA ^= memory.get(addr);
+        regA ^= memory.get(addr, true);
         EOR();
       },
 
       i56: function () {
         var addr = (popByte() + regX) & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         LSR(value);
       },
 
@@ -843,24 +947,24 @@ function SimulatorWidget(node) {
 
       i59: function () {
         var addr = popWord() + regY;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA ^= value;
         EOR();
       },
 
       i5d: function () {
         var addr = popWord() + regX;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         regA ^= value;
         EOR();
       },
 
       i5e: function () {
         var addr = popWord() + regX;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         LSR(value);
       },
 
@@ -872,14 +976,14 @@ function SimulatorWidget(node) {
       i61: function () {
         var zp = (popByte() + regX) & 0xff;
         var addr = memory.getWord(zp);
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testADC(value);
         //ADC
       },
 
       i65: function () {
         var addr = popByte();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testADC(value);
         //ADC
       },
@@ -887,11 +991,11 @@ function SimulatorWidget(node) {
       i66: function () {
         var sf = carrySet();
         var addr = popByte();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
         if (sf) { value |= 0x80; }
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROR(value);
       },
 
@@ -922,7 +1026,7 @@ function SimulatorWidget(node) {
 
       i6d: function () {
         var addr = popWord();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testADC(value);
         //ADC
       },
@@ -930,11 +1034,11 @@ function SimulatorWidget(node) {
       i6e: function () {
         var sf = carrySet();
         var addr = popWord();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
         if (sf) { value |= 0x80; }
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROR(value);
       },
 
@@ -947,14 +1051,14 @@ function SimulatorWidget(node) {
       i71: function () {
         var zp = popByte();
         var addr = memory.getWord(zp);
-        var value = memory.get(addr + regY);
+        var value = memory.get(addr + regY, true);
         testADC(value);
         //ADC
       },
 
       i75: function () {
         var addr = (popByte() + regX) & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testADC(value);
         //ADC
       },
@@ -962,11 +1066,11 @@ function SimulatorWidget(node) {
       i76: function () {
         var sf = carrySet();
         var addr = (popByte() + regX) & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
         if (sf) { value |= 0x80; }
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROR(value);
       },
 
@@ -978,14 +1082,14 @@ function SimulatorWidget(node) {
 
       i79: function () {
         var addr = popWord();
-        var value = memory.get(addr + regY);
+        var value = memory.get(addr + regY, true);
         testADC(value);
         //ADC
       },
 
       i7d: function () {
         var addr = popWord();
-        var value = memory.get(addr + regX);
+        var value = memory.get(addr + regX, true);
         testADC(value);
         //ADC
       },
@@ -993,33 +1097,33 @@ function SimulatorWidget(node) {
       i7e: function () {
         var sf = carrySet();
         var addr = popWord() + regX;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         setCarryFlagFromBit0(value);
         value = value >> 1;
         if (sf) { value |= 0x80; }
-        memory.storeByte(addr, value);
+        memory.storeByte(addr, value, true);
         ROR(value);
       },
 
       i81: function () {
         var zp = (popByte() + regX) & 0xff;
         var addr = memory.getWord(zp);
-        memory.storeByte(addr, regA);
+        memory.storeByte(addr, regA, true);
         //STA
       },
 
       i84: function () {
-        memory.storeByte(popByte(), regY);
+        memory.storeByte(popByte(), regY, true);
         //STY
       },
 
       i85: function () {
-        memory.storeByte(popByte(), regA);
+        memory.storeByte(popByte(), regA, true);
         //STA
       },
 
       i86: function () {
-        memory.storeByte(popByte(), regX);
+        memory.storeByte(popByte(), regX, true);
         //STX
       },
 
@@ -1036,17 +1140,17 @@ function SimulatorWidget(node) {
       },
 
       i8c: function () {
-        memory.storeByte(popWord(), regY);
+        memory.storeByte(popWord(), regY, true);
         //STY
       },
 
       i8d: function () {
-        memory.storeByte(popWord(), regA);
+        memory.storeByte(popWord(), regA, true);
         //STA
       },
 
       i8e: function () {
-        memory.storeByte(popWord(), regX);
+        memory.storeByte(popWord(), regX, true);
         //STX
       },
 
@@ -1059,22 +1163,22 @@ function SimulatorWidget(node) {
       i91: function () {
         var zp = popByte();
         var addr = memory.getWord(zp) + regY;
-        memory.storeByte(addr, regA);
+        memory.storeByte(addr, regA, true);
         //STA
       },
 
       i94: function () {
-        memory.storeByte((popByte() + regX) & 0xff, regY);
+        memory.storeByte((popByte() + regX) & 0xff, regY, true);
         //STY
       },
 
       i95: function () {
-        memory.storeByte((popByte() + regX) & 0xff, regA);
+        memory.storeByte((popByte() + regX) & 0xff, regA, true);
         //STA
       },
 
       i96: function () {
-        memory.storeByte((popByte() + regY) & 0xff, regX);
+        memory.storeByte((popByte() + regY) & 0xff, regX, true);
         //STX
       },
 
@@ -1085,7 +1189,7 @@ function SimulatorWidget(node) {
       },
 
       i99: function () {
-        memory.storeByte(popWord() + regY, regA);
+        memory.storeByte(popWord() + regY, regA, true);
         //STA
       },
 
@@ -1096,7 +1200,7 @@ function SimulatorWidget(node) {
 
       i9d: function () {
         var addr = popWord();
-        memory.storeByte(addr + regX, regA);
+        memory.storeByte(addr + regX, regA, true);
         //STA
       },
 
@@ -1108,7 +1212,7 @@ function SimulatorWidget(node) {
       ia1: function () {
         var zp = (popByte() + regX) & 0xff;
         var addr = memory.getWord(zp);
-        regA = memory.get(addr);
+        regA = memory.get(addr, true);
         LDA();
       },
 
@@ -1118,17 +1222,17 @@ function SimulatorWidget(node) {
       },
 
       ia4: function () {
-        regY = memory.get(popByte());
+        regY = memory.get(popByte(), true);
         LDY();
       },
 
       ia5: function () {
-        regA = memory.get(popByte());
+        regA = memory.get(popByte(), true);
         LDA();
       },
 
       ia6: function () {
-        regX = memory.get(popByte());
+        regX = memory.get(popByte(), true);
         LDX();
       },
 
@@ -1150,17 +1254,17 @@ function SimulatorWidget(node) {
       },
 
       iac: function () {
-        regY = memory.get(popWord());
+        regY = memory.get(popWord(), true);
         LDY();
       },
 
       iad: function () {
-        regA = memory.get(popWord());
+        regA = memory.get(popWord(), true);
         LDA();
       },
 
       iae: function () {
-        regX = memory.get(popWord());
+        regX = memory.get(popWord(), true);
         LDX();
       },
 
@@ -1173,22 +1277,22 @@ function SimulatorWidget(node) {
       ib1: function () {
         var zp = popByte();
         var addr = memory.getWord(zp) + regY;
-        regA = memory.get(addr);
+        regA = memory.get(addr, true);
         LDA();
       },
 
       ib4: function () {
-        regY = memory.get((popByte() + regX) & 0xff);
+        regY = memory.get((popByte() + regX) & 0xff, true);
         LDY();
       },
 
       ib5: function () {
-        regA = memory.get((popByte() + regX) & 0xff);
+        regA = memory.get((popByte() + regX) & 0xff, true);
         LDA();
       },
 
       ib6: function () {
-        regX = memory.get((popByte() + regY) & 0xff);
+        regX = memory.get((popByte() + regY) & 0xff, true);
         LDX();
       },
 
@@ -1198,7 +1302,7 @@ function SimulatorWidget(node) {
 
       ib9: function () {
         var addr = popWord() + regY;
-        regA = memory.get(addr);
+        regA = memory.get(addr, true);
         LDA();
       },
 
@@ -1210,19 +1314,19 @@ function SimulatorWidget(node) {
 
       ibc: function () {
         var addr = popWord() + regX;
-        regY = memory.get(addr);
+        regY = memory.get(addr, true);
         LDY();
       },
 
       ibd: function () {
         var addr = popWord() + regX;
-        regA = memory.get(addr);
+        regA = memory.get(addr, true);
         LDA();
       },
 
       ibe: function () {
         var addr = popWord() + regY;
-        regX = memory.get(addr);
+        regX = memory.get(addr, true);
         LDX();
       },
 
@@ -1235,19 +1339,19 @@ function SimulatorWidget(node) {
       ic1: function () {
         var zp = (popByte() + regX) & 0xff;
         var addr = memory.getWord(zp);
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         doCompare(regA, value);
         //CPA
       },
 
       ic4: function () {
-        var value = memory.get(popByte());
+        var value = memory.get(popByte(), true);
         doCompare(regY, value);
         //CPY
       },
 
       ic5: function () {
-        var value = memory.get(popByte());
+        var value = memory.get(popByte(), true);
         doCompare(regA, value);
         //CPA
       },
@@ -1276,13 +1380,13 @@ function SimulatorWidget(node) {
       },
 
       icc: function () {
-        var value = memory.get(popWord());
+        var value = memory.get(popWord(), true);
         doCompare(regY, value);
         //CPY
       },
 
       icd: function () {
-        var value = memory.get(popWord());
+        var value = memory.get(popWord(), true);
         doCompare(regA, value);
         //CPA
       },
@@ -1301,13 +1405,13 @@ function SimulatorWidget(node) {
       id1: function () {
         var zp = popByte();
         var addr = memory.getWord(zp) + regY;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         doCompare(regA, value);
         //CMP
       },
 
       id5: function () {
-        var value = memory.get((popByte() + regX) & 0xff);
+        var value = memory.get((popByte() + regX) & 0xff, true);
         doCompare(regA, value);
         //CMP
       },
@@ -1324,14 +1428,14 @@ function SimulatorWidget(node) {
 
       id9: function () {
         var addr = popWord() + regY;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         doCompare(regA, value);
         //CMP
       },
 
       idd: function () {
         var addr = popWord() + regX;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         doCompare(regA, value);
         //CMP
       },
@@ -1350,20 +1454,20 @@ function SimulatorWidget(node) {
       ie1: function () {
         var zp = (popByte() + regX) & 0xff;
         var addr = memory.getWord(zp);
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testSBC(value);
         //SBC
       },
 
       ie4: function () {
-        var value = memory.get(popByte());
+        var value = memory.get(popByte(), true);
         doCompare(regX, value);
         //CPX
       },
 
       ie5: function () {
         var addr = popByte();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testSBC(value);
         //SBC
       },
@@ -1390,14 +1494,14 @@ function SimulatorWidget(node) {
       },
 
       iec: function () {
-        var value = memory.get(popWord());
+        var value = memory.get(popWord(), true);
         doCompare(regX, value);
         //CPX
       },
 
       ied: function () {
         var addr = popWord();
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testSBC(value);
         //SBC
       },
@@ -1416,14 +1520,14 @@ function SimulatorWidget(node) {
       if1: function () {
         var zp = popByte();
         var addr = memory.getWord(zp);
-        var value = memory.get(addr + regY);
+        var value = memory.get(addr + regY, true);
         testSBC(value);
         //SBC
       },
 
       if5: function () {
         var addr = (popByte() + regX) & 0xff;
-        var value = memory.get(addr);
+        var value = memory.get(addr, true);
         testSBC(value);
         //SBC
       },
@@ -1440,14 +1544,14 @@ function SimulatorWidget(node) {
 
       if9: function () {
         var addr = popWord();
-        var value = memory.get(addr + regY);
+        var value = memory.get(addr + regY, true);
         testSBC(value);
         //SBC
       },
 
       ifd: function () {
         var addr = popWord();
-        var value = memory.get(addr + regX);
+        var value = memory.get(addr + regX, true);
         testSBC(value);
         //SBC
       },
@@ -1537,6 +1641,7 @@ function SimulatorWidget(node) {
       if (!codeRunning && !debugging) { return; }
 
       setRandomByte();
+      memory.clearLastAccess();
       executeNextInstruction();
 
       if ((regPC === 0) || (!codeRunning && !debugging)) {
@@ -1615,9 +1720,15 @@ function SimulatorWidget(node) {
       }
     }
 
+    function getCurrentPC() {
+
+      return regPC;
+    }
+
     // reset() - Reset CPU and memory.
     function reset() {
       display.reset();
+      memory.clearLastAccess();
       for (var i = 0; i < 0x600; i++) { // clear ZP, stack and screen
         memory.set(i, 0x00);
       }
@@ -1645,7 +1756,8 @@ function SimulatorWidget(node) {
       gotoAddr: gotoAddr,
       reset: reset,
       stop: stop,
-      toggleMonitor: toggleMonitor
+      toggleMonitor: toggleMonitor,
+      getCurrentPC: getCurrentPC
     };
   }
 
@@ -1818,10 +1930,25 @@ function SimulatorWidget(node) {
       ["STY", null, 0x84, 0x94, null, 0x8c, null, null, null, null, null, null, null],
       ["---", null, null, null, null, null, null, null, null, null, null, null, null]
     ];
+
+    function getCodeStartAddress() {
+
+      return 0x600;
+    }
+
+    function getCodeEndAddress() {
+
+      return getCodeStartAddress() + codeLen;
+    }
+
+    function isCodeAddress(addr) {
+
+      return getCodeStartAddress() <= addr && addr<= getCodeEndAddress();
+    }
     
     // Assembles the code into memory
     function assembleCode() {
-      var BOOTSTRAP_ADDRESS = 0x600;
+      var BOOTSTRAP_ADDRESS = getCodeStartAddress();
   
       simulator.reset();
       labels.reset();
@@ -2546,7 +2673,10 @@ function SimulatorWidget(node) {
         return defaultCodePC;
       },
       hexdump: hexdump,
-      disassemble: disassemble
+      disassemble: disassemble,
+      getCodeStartAddress: getCodeStartAddress,
+      getCodeEndAddress: getCodeEndAddress,
+      isCodeAddress: isCodeAddress,
     };
   }
 
diff --git a/simulator/style.css b/simulator/style.css
index 9dd1529..0f9d8b6 100644
--- a/simulator/style.css
+++ b/simulator/style.css
@@ -76,6 +76,34 @@
   display: none;
 }
 
+.monitor-code {
+  background: rgba(255, 235, 0, .4);
+}
+
+.monitor-read, .monitor-write {
+  font-weight: bold;
+}
+
+.monitor-read {
+  color: #000;
+}
+
+.monitor-write {
+  color: #080;
+}
+
+.monitor-random {
+  color: #FA33FA;
+}
+
+.monitor-lastkey {
+  color: #8C008C;
+}
+
+.monitor-pc {
+  color: #C86400;
+}
+
 .messages {
   margin: 0;
   padding: 6px;

From 663887ea4b526e73d238868096df9a03005aa0ce Mon Sep 17 00:00:00 2001
From: Bailey Parker <b@ileyparker.com>
Date: Sat, 14 Mar 2015 13:33:13 -0400
Subject: [PATCH 2/2] Adds notes to clarify new behavior

---
 _includes/end.html    | 2 ++
 _includes/widget.html | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/_includes/end.html b/_includes/end.html
index cf041b3..099c341 100644
--- a/_includes/end.html
+++ b/_includes/end.html
@@ -50,5 +50,7 @@
 $d: Light green
 $e: Light blue
 $f: Light grey
+
+In the monitor, when a byte in memory is read it is displayed in bold. If a byte in memory is written, it is displayed in bold and colored green. The special random byte is pink and the last keypress byte is purple. The memory locations corresponding to the display have a transparent highlight that match their color. The compiled program in memory is highlighted with yellow and the memory location of the PC is colored orange.
     </div>
 </div>
diff --git a/_includes/widget.html b/_includes/widget.html
index cc6ff3b..3288a12 100644
--- a/_includes/widget.html
+++ b/_includes/widget.html
@@ -59,5 +59,7 @@
 $d: Light green
 $e: Light blue
 $f: Light grey
+
+In the monitor, when a byte in memory is read it is displayed in bold. If a byte in memory is written, it is displayed in bold and colored green. The special random byte is pink and the last keypress byte is purple. The memory locations corresponding to the display have a transparent highlight that match their color. The compiled program in memory is highlighted with yellow and the memory location of the PC is colored orange.
     </div>
 </div>