164
Table 8.12
Bus Cycle States when Accessing Address Spaces
CPU Read Cycle, DMAC Dual Mode Read Cycle, DMAC
Single Mode Memory Read/Write Cycle
Address Space
Corresponding Bits in
WCR1 and WCR2 = 0
Corresponding Bits in
WCR1 and WCR2 = 1
External memory (areas 1, 3–5, 7)
1 state fixed;
WAIT
signal
ignored
2 wait states from
WAIT
signal
External memory (Areas 0, 2, 6;
long wait avail-able)
1 state + long wait state
*
,
WAIT
signal ignored
1 state + long wait state
*
+
wait
states from
WAIT
signal
DRAM space (area 1)
Column address cycle:
1 state,
WAIT
signal ignored
(short pitch)
Column address cycle:
2 wait states from
WAIT
signal (long pitch)
Multiplexed I/O space (area 6)
4 wait states from
WAIT
signal
On-chip supporting module space
(area 5)
3 states fixed,
WAIT
signal ignored
On-chip ROM (area 0)
1 state fixed,
WAIT
signal ignored
On-chip RAM (area 7)
1 state fixed,
WAIT
signal ignored
CPU Write Cycle, DMAC Dual Mode Memory Write Cycle
(WW1 of WCR1)
Address Space
WW1 of WCR1=0
WW1 of WCR1=1
External memory (area 1)
Setting prohibited
2 wait state from
WAIT
signal
External memory (areas 3–5, 7)
2 wait states from
WAIT
signal
External memory (Areas
0, 2, 6; long wait available)
1 state + long wait state
*
+
wait states from
WAIT
signal
DRAM space (area 1)
Column address cycle:
1 state,
WAIT
signal
ignored (short pitch)
Column address cycle:
2 wait states from
WAIT
signal (long pitch)
Multiplexed I/O space (area 6)
4 wait states from
WAIT
signal
On-chip peripheral module space
(area 5)
3 states fixed,
WAIT
signal ignored
On-chip ROM (area 0)
1 state fixed,
WAIT
signal ignored
On-chip RAM (area 7)
1 state fixed,
WAIT
signal ignored
Note:
*
The number of long wait states (1 to 4) is set in WCR3.
For details on bus cycles when external spaces are accessed, see section 8.4, Accessing External
Memory Space, section 8.5, DRAM Interface Operation, and section 8.6, Address/Data
Multiplexed I/O Space Access.
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