#define CMD_PREFIX 0x5a
#define CMD_MD_SEND 0xc1 /* send to MD: addr[3], len[3], data[] */
#define CMD_MD_RECV 0xc2 /* recv from MD: addr[3], len[3], data[] */
+#define CMD_JUMP 0xc3 /* jump to addr: addr[3] */
+#define CMD_TEST 0xc4 /* test code */
+#define CMD_FIRST CMD_MD_SEND
+#define CMD_LAST CMD_TEST