Valid Strobes - Hitachi H8S/2646 Hardware Manual

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.
160
Read/ Valid
Write Address Strobe
RD
Read —
HWR
Write —
RD
Read Even
Odd
HWR
Write Even
LWR
Odd
RD
Read —
HWR, LWR Valid
Write —
Upper Data Bus Lower data bus
(D15 to D8) (D7 to D0)
Valid Invalid
Hi-Z
Valid Invalid
Invalid Valid
Valid Hi-Z
Hi-Z Valid
Valid Valid
Valid