diff --git a/internal/vm/exec_funcs.go b/internal/vm/exec_funcs.go
index 169d6ce..57b9e35 100644
--- a/internal/vm/exec_funcs.go
+++ b/internal/vm/exec_funcs.go
@@ -330,6 +330,15 @@ func execBPL(a *Appleone, o op) error {
 	return nil
 }
 
+// branch on C = 1                  N Z C I D V
+//                                  - - - - - -
+func execBCS(a *Appleone, o op) error {
+	if a.getCarry() != 0 {
+		a.branch(o)
+	}
+	return nil
+}
+
 // X - M                            N Z C I D V
 //                                  + + + - - -
 func execCPX(a *Appleone, o op) error {
diff --git a/internal/vm/opcodes.go b/internal/vm/opcodes.go
index ea87c3c..9178632 100644
--- a/internal/vm/opcodes.go
+++ b/internal/vm/opcodes.go
@@ -336,7 +336,7 @@ var opcodes = map[uint8]op{
 	// addressing    assembler    opc  bytes  cyles
 	// --------------------------------------------
 	// relative      BCS oper     B0   2      2**
-	0xB0: newOp("BCS", 0xB0, 2, relative, todo),
+	0xB0: newOp("BCS", 0xB0, 2, relative, execBCS),
 
 	// CPX Compare Memory and Index X
 	// addressing    assembler    opc  bytes  cyles