Hitachi H8/3008 Hardware Manual page 590

TDR—Transmit Data Register
7
Bit
Initial value 1
Read/Write R/W
574
6 5
1 1
R/W R/W
Serial transmit data
H'FFFB3
4 3
1 1
R/W R/W
SCI0
2 1
1 1
R/W R/W
0
1
R/W