diff --git a/src/emu/i8088.rs b/src/emu/i8088.rs
index c36c578..c5408fb 100644
--- a/src/emu/i8088.rs
+++ b/src/emu/i8088.rs
@@ -298,8 +298,10 @@ impl i8088 {
           0x2e => nop[seg=cs, prefix] / 2,
           0x36 => nop[seg=ss, prefix] / 2,
           0x3e => nop[seg=ds, prefix] / 2,
-          0x60 => show[cpu] / 0,           // Fake opcode for debugging
-          0x61 => peek[seg=ds, addr] / 0,  // Fake opcode for debugging
+          0x60 => show[cpu] / 0,               // Fake opcode for debugging
+          0x61 => peek[seg=ds, addr] / 0,      // Fake opcode for debugging
+          0x62 _ => assert[modrm8, d8] / 0,    // Fake opcode for debugging
+          0x63 _ => assert[modrm16, d16] / 0,  // Fake opcode for debugging
           0x88 _ => mov[modrm8, r8] / "2/13+",
           0x89 _ => mov[modrm16, r16] / "2/13+",
           0x8A _ => mov[r8, modrm8] / "2/12+",
diff --git a/src/emu/operations.rs b/src/emu/operations.rs
index d0c9118..9f52bc4 100644
--- a/src/emu/operations.rs
+++ b/src/emu/operations.rs
@@ -1,3 +1,5 @@
+use std::fmt::Debug;
+
 use emu::byteorder::{ByteOrder, LittleEndian};
 use emu::dos;
 use emu::i8088::i8088;
@@ -5,6 +7,12 @@ use emu::operands::{Addr, Address, LValue, Reg, RValue};
 use emu::pc::Bus;
 use emu::util::segoff_to_addr;
 
+pub fn assert<T: Debug + Eq>(loc: &impl RValue<T>, val: &impl RValue<T>) {
+  assert_eq!(loc.read(), val.read(),
+             "ASSERT instruction failed: {:#2X?} != {:#2X?}", loc.read(), val.read());
+  println!("ASSERT pass: {:#2X?} == {:#2X?}", loc.read(), val.read());
+}
+
 pub fn show(cpu: &mut i8088) {
   println!("{:#X?}", cpu);
 }