diff --git a/testcode/assembler/illegal.s b/testcode/assembler/illegal.s
new file mode 100644
index 000000000..53b9ec5b0
--- /dev/null
+++ b/testcode/assembler/illegal.s
@@ -0,0 +1,43 @@
+
+        .setcpu         "6502X"
+
+
+.macro  test    opc
+
+        opc     $00
+        opc     $00,x
+        opc     ($00,x)
+        opc     ($00),y
+        opc     $1234
+        opc     $1234,x
+        opc     $1234,y
+
+.endmacro
+
+
+        test    slo
+        test    rla
+        test    sre
+        test    rra
+        test    dcp
+        test    isc
+
+        sax     $00
+        sax     $00,y
+        sax     ($00,x)
+        sax     $1234
+
+        lax     $00
+        lax     $00,y
+        lax     ($00,x)
+        lax     ($00),y
+        lax     $1234
+        lax     $1234,y
+
+        anc     #$55
+        alr     #$55
+        arr     #$55
+        axs     #$55
+
+        las     $1234,y
+