+#define IBMPC_PROTOCOL_NO 0
+#define IBMPC_PROTOCOL_AT 0x10
+#define IBMPC_PROTOCOL_AT_Z150 0x11
+#define IBMPC_PROTOCOL_XT 0x20
+#define IBMPC_PROTOCOL_XT_IBM 0x21
+#define IBMPC_PROTOCOL_XT_CLONE 0x22
+#define IBMPC_PROTOCOL_XT_ERROR 0x23
+
+// Error numbers