Hitachi H8S/2633 Hardware Manual page 187

7.4.3 Valid Strobes
Table 7-4 shows the data buses used and valid strobes for the access spaces.
In a read, the RD signal is valid without discrimination between the upper and lower halves of the
data bus.
In a write, the HWR signal is valid for the upper half of the data bus, and the LWR signal for the
lower half.
Table 7-4 Data Buses Used and Valid Strobes
Access
Area Size
8-bit access Byte
space
16-bit access Byte
space
Word
Note: Hi-Z: High impedance.
Invalid: Input state; input value is ignored.
Read/
Write Address
Read —
Write —
Read Even
Odd
Write Even
Odd
Read —
Write —
Valid Upper Data Bus
Strobe (D15 to D8)
RD
Valid
HWR
RD
Valid
Invalid
HWR
Valid
LWR
Hi-Z
RD
Valid
HWR, LWR Valid
Lower data bus
(D7 to D0)
Invalid
Hi-Z
Invalid
Valid
Hi-Z
Valid
Valid
Valid
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