diff --git a/src/emulator/main.rs b/src/emulator/main.rs
index f123e6c..e721ae0 100644
--- a/src/emulator/main.rs
+++ b/src/emulator/main.rs
@@ -18,6 +18,9 @@ pub struct EmulatorState {
     sp: u16,
     /// Memory pointer
     pc: u16,
+    /// Enable interrupts
+    ei: bool,
+    /// Memory map
     memory: [u8; 8000],
 }
 
@@ -86,6 +89,21 @@ fn set_register(register: Register, value: u8, state: &mut EmulatorState) {
     };
 }
 
+/// Print values of registers and flags to stdout
+fn print_state(state: &EmulatorState) {
+    // State
+    println!("\nsp\tpc\tei");
+    println!("{}\t{}\t{}", state.sp, state.pc, state.ei);
+
+    // Registers
+    println!("\nB\tC\tD\tE\tH\tL\tA");
+    println!("{}\t{}\t{}\t{}\t{}\t{}\t{}", state.b, state.c, state.d, state.e, state.h, state.l, state.a);
+
+    // Flags
+    println!("\nz\ts\tp\tc");
+    println!("{}\t{}\t{}\t{}", state.cc.z, state.cc.s, state.cc.p, state.cc.c);
+}
+
 fn main() {
     let mut state = EmulatorState {
         a: 0,
@@ -98,6 +116,7 @@ fn main() {
         sp: 0,
         cc: ConditionCodes { z: true, s: true, p: true, c: true },
         pc: 0,
+        ei: true,
         memory: [0; 8000],
     };
 
@@ -140,7 +159,18 @@ fn tick(state: &mut EmulatorState) {
         0x88..=0x8f => arithmetic::adc(register_from_num(instruction & 0xf), state), // ADC
         0xc6        => arithmetic::adi(next_byte(), state), // ADI
         0xce        => arithmetic::aci(next_byte(), state), // ACI
-        _           => not_implemented(state),
+
+
+        /* Special */
+        0xfb => state.ei = true,  // EI
+        0xf3 => state.ei = false, // DI
+        0x76 => if state.ei { todo!() } else {     // HLT
+            println!("HLT called after DI; exiting.");
+            print_state(state);
+            std::process::exit(0);
+        },
+
+        _ => not_implemented(state),
     }
 
     state.pc += 1;