CHAPTER 5 MEMORY ACCESS CONTROL FUNCTION
User’s Manual U12688EJ4V0UM00
132
5.2.3 On-page/off-page judgment
Whether a page ROM cycle is on-page or off-page is judged by latching the address of the previous cycle and
comparing it with the address of the current cycle.
Using the page ROM configuration register (PRC), one of the addresses (A3 to A5) is set as the masking address
(no comparison is made) according to the configuration of the connected page ROM and the number of continuously
readable bits.
Figure 5-4. On-Page/Off-Page Judgment for Page ROM Connection (1/2)
(a) In the case of 16 Mbit (1 M
××××
16) page ROM (4-word page access)
a23
a22
a21
a20
a19
a18
a5
a4
a3
A23
A22
A21
A20
A19
A18
A5
A4
A3
A2
A1
A0
A19
Internal address latch
V850E/MS1
address output
Page ROM address
A18
A17
Off-page address
On-page address
Continuous reading possible:
16-bit data bus width
×
4 words
A4
A3
A2
A1
A0
MA5
0
MA4
0
MA3
0
PRC register setting
Comparison
Содержание V850E/MS1 UPD703100
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