more sane directory name, updated binaries

src/kernal/iec/iec_check_devnum.s

@@ -0,0 +1,36 @@
+// #LAYOUT# STD *        #TAKE
+// #LAYOUT# *   KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+//
+// Checks whether device number (in .A) is a correct IEC device number
+//
+// Preserves .A, .X and .Y
+//
+
+
+#if CONFIG_IEC
+
+iec_check_devnum_lvs: // for load/verify/save
+
+	cmp #$08 // below 8 are illegal for load/save
+	bcc iec_check_devnum_failed
+
+	// FALLTROUGH
+
+iec_check_devnum_oc: // for open/close
+
+	cmp #$04 // below 4 are illegal, reserved for non-IEC devices on Commodore
+	bcc iec_check_devnum_failed
+
+	// 31 and above are illegal too, due to IEC command encoding scheme,
+	// see https://www.pagetable.com/?p=1031
+	cmp #$1F // sets carry for 31 or above
+	rts
+
+iec_check_devnum_failed:
+
+	sec // indicate non-IEC device
+	rts
+
+#endif // CONFIG_IEC