diff --git a/sketches/simulator-sketch-v3.js b/sketches/simulator-sketch-v3.js
new file mode 100644
index 0000000..c5771d0
--- /dev/null
+++ b/sketches/simulator-sketch-v3.js
@@ -0,0 +1,213 @@
+// NOTES:
+//
+// - instructions are two bytes long:
+//   one byte for the opcode, one for the argument
+
+// STATE
+
+const CPU = {
+  running: false,
+  IP: 0,
+  CF: 0,
+  Acc: 0,
+  memory: null,
+  loadMemory: (data) => { // data: Uint8Array
+    // TODO: check length of data
+    CPU.memory = data;
+  },
+}
+
+
+// FUNCTIONS THAT MODIFY STATE
+
+const Instructions = {
+  end: () => {
+    console.log('END');
+    CPU.running = false;
+  },
+
+  store_lit: (lit) => {
+    console.log('STO lit#');
+    CPU.memory[lit] = CPU.Acc;
+    logTableTitled(CPU.memory, 'Current memory');
+    CPU.IP = CPU.IP += 2;
+  },
+
+  store_addr: (addr) => {
+    console.log('STO addr');
+    CPU.memory[CPU.memory[addr]] = CPU.Acc;
+    logTableTitled(CPU.memory, 'Memory');
+    CPU.IP = CPU.IP += 2;
+  },
+
+  load_lit: (lit) => {
+    console.log('LDA lit#');
+    CPU.Acc = lit;
+    CPU.IP = CPU.IP += 2;
+  },
+
+  load_addr: (addr) => {
+    console.log('LDA addr');
+    console.log('mem at addr: ', CPU.memory[addr]);
+    CPU.Acc = CPU.memory[addr];
+    CPU.IP = CPU.IP += 2;
+  },
+
+  add_lit: (lit) => {
+    console.log("ADD lit");
+    let sum = CPU.Acc + lit;
+    if (sum > 15) {
+      CPU.CF = 1;
+      CPU.Acc = (sum % 15) - 1;
+    } else {
+      CPU.CF = 0;
+      CPU.Acc = sum;
+    }
+    CPU.IP = CPU.IP += 2;
+  },
+
+  add_addr: (addr) => {
+    console.log("ADD addr");
+    let sum = CPU.Acc + CPU.memory[addr];
+    if (sum > 15) {
+      CPU.CF = 1;
+      CPU.Acc = (sum % 15) - 1;
+    } else {
+      CPU.CF = 0;
+      CPU.Acc = sum;
+    }
+    CPU.IP = CPU.IP += 2;
+  },
+
+  sub_lit: (lit) => { // TODO: carry flag
+    console.log("SUB lit");
+    CPU.Acc = CPU.Acc - lit;
+    CPU.IP = CPU.IP += 2;
+  },
+
+  sub_addr: (addr) => { // TODO: carry flag
+    console.log("SUB addr");
+    CPU.Acc = CPU.Acc - CPU.memory[addr];
+    CPU.IP = CPU.IP += 2;
+  },
+
+  hop_lit: (lit) => {
+    console.log("HOP lit");
+    console.log(` ↳ Memory at IP+2 and +3: ${CPU.memory[CPU.IP+2]}, ${CPU.memory[CPU.IP+3]}`);
+    if (CPU.Acc === lit) {
+      CPU.IP += 4;
+    } else {
+      CPU.IP += 2;
+    }
+  },
+
+  hop_addr: (addr) => {
+    console.log("HOP addr");
+    if (CPU.Acc === CPU.memory[addr]) {
+      CPU.IP += 4;
+    } else {
+      CPU.IP += 2;
+    }
+  },
+
+  jump_lit: (lit) => {
+    console.log("JMP lit");
+    CPU.IP = lit;
+  },
+
+  jump_addr: (addr) => {
+    console.log("JMP addr");
+    CPU.IP = CPU.memory[addr];
+  },
+
+  carry_clear: () => {
+    console.log("CFC");
+    CPU.CF = 0;
+    CPU.IP += 2;
+  },
+
+  carry_hop: () => {
+    console.log("CHP");
+    console.log(` ↳ Memory at IP+2 and +3: ${CPU.memory[CPU.IP+2]}, ${CPU.memory[CPU.IP+3]}`);
+    console.table(CPU.memory);
+    if (CPU.CF != 0) {
+      CPU.IP += 4;
+    } else {
+      CPU.IP += 2;
+    }
+  },
+}
+
+const opcodes2mnemonics = {
+  0: (arg) => Instructions.end(arg),
+  1: (arg) => Instructions.store_lit(arg),
+  2: (arg) => Instructions.store_addr(arg),
+  3: (arg) => Instructions.load_lit(arg),
+  4: (arg) => Instructions.load_addr(arg),
+  5: (arg) => Instructions.add_lit(arg),
+  6: (arg) => Instructions.add_addr(arg),
+  7: (arg) => Instructions.sub_lit(arg),
+  8: (arg) => Instructions.sub_addr(arg),
+  9: (arg) => Instructions.hop_lit(arg),
+  10: (arg) => Instructions.hop_addr(arg),
+  11: (arg) => Instructions.jump_lit(arg),
+  12: (arg) => Instructions.jump_addr(arg),
+  13: (arg) => Instructions.carry_clear(arg),
+  14: (arg) => Instructions.carry_hop(arg),
+};
+
+function stepCPU() {
+  console.group("Step CPU");
+  let opcode = CPU.memory[CPU.IP];
+  let argument = CPU.memory[CPU.IP+1];
+
+  console.log(`OP: ${opcode}   ARG: ${argument}`);
+
+  let instruction = opcodes2mnemonics[opcode];
+  instruction(argument);
+
+  logCPUState();
+  console.groupEnd("Step CPU");
+}
+
+exports.runProgram = (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
+  console.log();
+  console.log("————————————————————————————————————————");
+  let time = new Date();
+  console.log( `Running at ${time.toLocaleTimeString('en-US')}` );
+  console.log("————————————————————————————————————————");
+  logCPUState();
+
+  CPU.running = true;
+  for (let i = 0; i < 255; i++) { // FIXME: temporary limit as a lazy way to halt infinite loops
+    if (!CPU.running) break;
+    if (CPU.IP >= CPU.memory.length) break;
+    stepCPU();
+  };
+}
+
+
+// FUNCTIONS THAT PULL INFO FROM STATE TO DISPLAY
+
+function logCPUState() {
+  console.log();
+  console.group('CPU state');
+  console.log( `Acc: ${CPU.Acc}   IP: ${CPU.IP}   CF: ${CPU.CF}   ${CPU.running ? "running" : "halted" }` );
+  console.log();
+  console.groupEnd('CPU state');
+};
+
+
+// FUNCTIONS FOR DISPLAYING DATA
+
+function num2hex(num) { return num.toString(16) };
+function hex2num(hex) { return parseInt(hex, 16) };
+
+logTableTitled = (memory, tableTitle) => {
+  console.log();
+  console.group(tableTitle);
+  console.table(memory);
+  console.groupEnd(tableTitle);
+};
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