Datasheet

Rev.6.00 Oct.28.2004 page 127 of 1016
REJ09B0138-0600H
6.4.3 Valid Strobes
Table 6-4 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 6-4 Data Buses Used and Valid Strobes
Area
Access
Size
Read/
Write Address
Valid
Strobe
Upper Data Bus
(D
15
to D
8
)
Lower data bus
(D
7
to D
0
)
8-bit access Byte Read — RD Valid Invalid
space
Write — HWR Hi-Z
16-bit access Byte Read Even RD Valid Invalid
space
Odd Invalid Valid
Write Even HWR Valid Hi-Z
Odd LWR Hi-Z Valid
Word Read — RD Valid Valid
Write — HWR, LWR Valid Valid
Legend:
Hi-Z: High impedance
Invalid: Input state; input value is ignored.