diff --git a/assemble-and-run.js b/assemble-and-run.js
index 4594a3a..0899f90 100644
--- a/assemble-and-run.js
+++ b/assemble-and-run.js
@@ -1,12 +1,15 @@
-// Usage: `node assemble-and-run.js assembly.asm`
+// Run:   `node assemble-and-run.js run assembly.asm`
+// Debug: `node assemble-and-run.js debug assembly.asm`
 
 const fs = require('fs');
 const computer = require('./simulator.js');
 const assembler = require('./assembler.js');
 const printMemory = require('./print-memory.js');
 
+const mode = process.argv[2];
+
 // console.log(`Reading ${filename}`);
-const filename = process.argv[2];
+const filename = process.argv[3];
 const inputFile_str = fs.readFileSync(filename, 'utf8');
 let machineCode = assembler.assemble(inputFile_str);
 
@@ -14,5 +17,8 @@ let machineCode = assembler.assemble(inputFile_str);
 // printMemory.printTable(machineCode);
 // console.groupEnd('Machine code output');
 
-computer.debugProgram(machineCode);
-//computer.displayProgram(machineCode);
\ No newline at end of file
+if (mode === "debug") {
+  computer.runProgram(machineCode, true);
+} else {
+  computer.runProgram(machineCode, false);
+}
\ No newline at end of file
diff --git a/package.json b/package.json
index 8471f39..bf83aa5 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,8 @@
 {
   "name": "paper-computer",
   "scripts": {
-    "assemble-and-run": "node assemble-and-run.js",
+    "display": "node assemble-and-run.js run",
+    "debug":   "node assemble-and-run.js debug",
     "assemble": "node assemble.js"
   }
 }
diff --git a/simulator.js b/simulator.js
index 1d76aca..00480ea 100644
--- a/simulator.js
+++ b/simulator.js
@@ -174,49 +174,25 @@ function stepCPU() {
   // console.groupEnd("Step CPU");
 }
 
-exports.debugProgram = (code) => {
-  console.log();
-  let time = new Date();
-  console.log( `┌─────────────────────┐`);
-              // Running at 11:48:15 AM
-  console.log( `│ Running at ${time.toLocaleTimeString('en-GB')} │` );
-  console.log( `└─────────────────────┘`);
+exports.runProgram = async (code, debug = false) => {
+  if (debug) logRunningHeader();
 
   CPU.loadMemory(code);
-  const initialMemory = JSON.parse(JSON.stringify(CPU.memory)); // Hack to make a copy-by-value -- https://stackoverflow.com/questions/18829099/copy-a-variables-value-into-another
-  logCPUState();
+  if (debug) logCPUState();
   CPU.running = true;
   let step = 0;
   while (true) {
     step = step + 1;
-    // FIXME: temporary limit as a lazy way to halt infinite loops:
-    if (CYCLE_LIMIT && (step > CYCLE_LIMIT)) { break; }
+    if (CYCLE_LIMIT && (step > CYCLE_LIMIT)) { break; } // Temporary limit as a lazy way to halt infinite loops:
     if (!CPU.running) break;
     if (CPU.IP >= CPU.memory.length) break;
+
+    if (!debug) console.clear();
     console.group('Display')
     display.printDisplay(CPU.memory);
-    console.log();
     console.groupEnd('Display');
-  };
-}
-
-exports.displayProgram = async (code) => {
-  CPU.loadMemory(code);
-  const initialMemory = JSON.parse(JSON.stringify(CPU.memory)); // Hack to make a copy-by-value -- https://stackoverflow.com/questions/18829099/copy-a-variables-value-into-another
-  CPU.running = true;
-
-  let step = 0;
-  while (true) {
-    step = step + 1;
-    // FIXME: temporary limit as a lazy way to halt infinite loops:
-    if (CYCLE_LIMIT && (step > CYCLE_LIMIT)) { break; }
-    if (!CPU.running) break;
-    if (CPU.IP >= CPU.memory.length) break;
-    stepCPU();
-    console.clear();
-    display.printDisplay(CPU.memory);
     logCPUState();
-    await new Promise(resolve => setTimeout(resolve, 75));
+    if (!debug) await new Promise(resolve => setTimeout(resolve, 75));
   };
 }
 
@@ -240,4 +216,12 @@ logTableTitled = (memory, tableTitle) => {
   console.group(tableTitle);
   console.table(memory);
   console.groupEnd(tableTitle);
-};
\ No newline at end of file
+};
+
+function logRunningHeader() {
+  console.log();
+  let time = new Date();
+  console.log( `┌─────────────────────┐`);
+  console.log( `│ Running at ${time.toLocaleTimeString('en-GB')} │` );
+  console.log( `└─────────────────────┘`);
+}
\ No newline at end of file