162
7.4.4
Basic Timing
8-Bit 2-State Access Space: Figure 7-6 shows the bus timing for an 8-bit 2-state access space.
When an 8-bit access space is accessed, the upper half (D15 to D8) of the data bus is used.
The
LWR
pin is fixed high. Wait states cannot be inserted.
Bus cycle
T
1
T
2
Address bus
ø
AS
CSn
RD
D15 to D8
Valid
D7 to D0
Invalid
Read
HWR
LWR
D15 to D8
Valid
D7 to D0
High impedance
Write
Note: n = 0 to 7
High
Figure 7-6 Bus Timing for 8-Bit 2-State Access Space