CHAPTER 5 MEMORY ACCESS CONTROL FUNCTION
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User’s Manual U14359EJ4V0UM
5.2.4 Page ROM configuration register (PRC)
This register specifies whether page ROM cycle on-page access is enabled or disabled. If on-page access is
enabled, the masking address (no comparison is made) out of the addresses (A3 to A6) corresponding to the
configuration of the connected page ROM and the number of bits that can be read continuously, as well as the
number of waits corresponding to the internal system clock, are set.
This register can be read/written in 16-bit units.
Caution
Write to the PRC register after reset, and then do not change the set value. Also, do not
access an external memory area other than the one for this initialization routine until the
initial setting of the PRC register is complete. However, it is possible to access external
memory areas whose initialization settings are complete.
15
0
PRC
Address
FFFFF49AH
After reset
7000H
14
PRW2
13
PRW1
12
PRW0
11
0
10
0
9
0
8
0
7
0
6
0
5
0
4
0
3
MA6
2
MA5
1
MA4
0
MA3
Bit position
Bit name
Function
Page-ROM On-page Wait Control
Sets the number of waits corresponding to the internal system clock.
The number of waits set by these bits is inserted only for on-page access. For off-page
access, the waits set by registers DWC0 and DWC1 are inserted.
PRW2
PRW1
PRW0
Number of inserted wait cycles
0
0
0
0
0
0
1
1
0
1
0
2
0
1
1
3
1
0
0
4
1
0
1
5
1
1
0
6
1
1
1
7
14 to 12
PRW2 to
PRW0
Mask Address
Each respective address (A6 to A3) corresponding to MA6 to MA3 is masked (by 1). The
masked address is not subject to comparison during on/off-page judgment, and is set
according to the number of continuously readable bits.
MA6
MA5
MA4
MA3
Number of continuously readable bits
0
0
0
0
4 words
×
16 bits (8 words
×
8 bits)
0
0
0
1
8 words
×
16 bits (16 words
×
8 bits)
0
0
1
1
16 words
×
16 bits (32 words
×
8 bits)
0
1
1
1
32 words
×
16 bits (64 words
×
8 bits)
1
1
1
1
64 words
×
16 bits (128 words
×
8 bits)
Other than above
Setting prohibited
3 to 0
MA6 to
MA3