Hitachi H8/3937 Series Hardware Manual page 219

1. Write access
Write access to the upper byte results in transfer of the upper-byte write data to TEMP. Next,
write access to the lower byte results in transfer of the data in TEMP to the upper register byte,
and direct transfer of the lower-byte write data to the lower register byte.
Figure 9-4 shows an example in which H'AA55 is written to TCF.
Write to upper byte
CPU
(H'AA)
Write to lower byte
CPU
(H'55)
Bus
interface
Bus
interface
Figure 9-4 Write Access to TCF (CPU → TCF)
Module data bus
TEMP
(H'AA)
TCFH TCFL
( ) (
Module data bus
TEMP
(H'AA)
TCFH TCFL
(H'AA) (H'55)
)
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