+/* all data is big endian */
+
#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_PC_SEND 0xc1 /* send to MD: addr[3], len[3], data[] */
+#define CMD_PC_RECV 0xc2 /* recv from MD: addr[3], len[3], data[] */
+#define CMD_JUMP 0xc3 /* jump to addr: addr[3] */
+#define CMD_IOSEQ 0xc4 /* perform i/o ops: count[2], [type[1], addr[3], data[{0,1,2,4}]]* */
+#define CMD_LOADSTATE 0xc5 /* load PD state: vram[64k], cram[128], vsram[128], vdp[32] */
+#define CMD_VRAM_RECV 0xc6 /* recv from MD: vram[64k] */
+#define CMD_TEST 0xc7 /* test code */
+
+#define CMD_FIRST CMD_PC_SEND
+#define CMD_LAST CMD_TEST
+#define IOSEQ_R8 0xb0
+#define IOSEQ_R16 0xb1
+#define IOSEQ_R32 0xb2
+#define IOSEQ_W8 0xb3
+#define IOSEQ_W16 0xb4
+#define IOSEQ_W32 0xb5