first public release

ed_undefined_nop_test.go

@@ -0,0 +1,15 @@
+package z80
+
+import "testing"
+
+// ED 80..9F (mostly undefined) act as NOP with 8 cycles per the implementation.
+// We probe one byte to cement the contract.
+func TestED_UndefinedActsAsNOP8Cycles(t *testing.T) {
+	cpu, mem, _ := testCPU()
+	// Use ED 80
+	loadProgram(cpu, mem, 0x0000, 0xED, 0x80)
+	pc := cpu.PC
+	c := mustStep(t, cpu)
+	assertEq(t, c, 8, "undefined ED opcode should be 8 cycles")
+	assertEq(t, cpu.PC, pc+2, "PC advanced over ED xx")
+}