rc2014: make SIO actually work on real hardware

my previous commit was only tested in emulation, I had init wrong.

blk/590

@@ -6,7 +6,7 @@
     0x18 _ ( CMD3 )
     0x24 _ ( CMD2/PTR4 ) 0b11000100 _ ( WR4/64x/1stop/nopar )
     0x03 _ ( PTR3 ) 0b11000001 _ ( WR3/RXen/8char )
-    0x05 _ ( PTR5 ) 0b11001000 _ ( WR5/TXen/8char )
+    0x05 _ ( PTR5 ) 0b01101000 _ ( WR5/TXen/8char )
     0x21 _ ( CMD2/PTR1 ) 0b00011000 _ ( WR1/Rx INT all chars )
     (im1)
 ;