MOS CIA Interrupt control/mask mechanics in place.

src/MOSCIA.js

       cia.__CTA = BITM.clear(cia.__CTA, 0);
     }
 
+    // Setting the interrupt bit for timer A
+    cia.__IC = BITM.set(cia.__IC, 0);
+
     // Check to see if timer modifies the PORT B bit 6.
     // If so, determine if it's a pulse or an toggle.
     if (BITM.isOn(cia.__CTA, 1))
       cia.__CTB = BITM.clear(cia.__CTB, 0);
     }
 
+    cia.__IC = BITM.set(cia.__IC, 1);
+
     if (BITM.isOn(cia.__CTB, 1))
       cia.__PDB = (BITM.isOn(cia.__CTB, 2) === 0) ? BITM.set(cia.__PDB, 7) : BITM.toggle(cia.__PDB, 7);
   }
 
     this.__CTA = 0;
     this.__CTB = 0;
+
     this.__IC = 0;
+    this.__ICMask = 0;
 
     this.__timerA = 0;
     this.__timerALatch = 0;
       case 0x0C: // Serial Data
         break;
       case 0x0D: // Interrupt Control
-        break;
+        let v = this.__IC;
+        this.__IC = 0;
+        return v; break;
       case 0x0E: // Control Timer Reg A
         val = this.__CTA; break;
       case 0x0F: // Control Timer Reg B
       case 0x0C: // Serial Data
         break;
       case 0x0D: // Interrupt Control
+        if (BITM.isOn(d & 0xFF, 7)){
+          for (let i=0; i < 5; i++){
+            if (BITM.isOn(d & 0xFF, i))
+              this.__ICMask = BITM.set(this.__ICMask, i);
+          }
+        } else {
+          for (let i=0; i < 5; i++){
+            if (BITM.isOn(d & 0xFF, i))
+              this.__ICMask = BITM.clear(this.__ICMask, i);
+          }
+        }
         break;
       case 0x0E: // Control Timer Reg A
         this.__CTA = d & 0xFF;