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4.2 Chip Select Area
4.2 Chip Select Area

A total of six types of chip select area are prepared for the bus interface.

Setting Chip Select Areas
Each area can be optionally located in units of at least 64 ki lobytes in a 4 gi gabyte area usi ng
the area select registers (ASR1 to ASR5) and area mask reg isters (AMR1 to AMR5).
If an attempt is made to access the area specified by these registers via the external bus, the
corresponding chip select signals CS0X to CS5X becom e active "L".
When the registers are reset, these pins excluding CS0X b ecome inactive and are set to "H."
<Note>
Area 0 is allocated to a space other than the areas specified by ASR1 to ASR5.
At reset time, the external area other than 00010000H to 0005FFFFH become s area 0.
Figure 4.2.1 (a) shows an example of area 1 to area 5 lo cated in units of 64 kilobytes from
00100000H to 0014FFFFH. Figure 4.2.1 (b) shows an example of area 1 located in 512
kilobytes from 00000000H to 0007FFFFH and area 2 to area 5 locat ed in 1 mega byte u nits from
00100000H to 004FFFFFH.
Figure 4.2-1 Example of Setting Chip Select Areas
00000000
H
00000000
H
CS1X(512K)
00080000
H
CS0X(512K)
00080000
H
CS0X(1Mbyte) 000FFFFF
H
CS2X(1Mbyte)
000FFFFF
H
001FFFFF
H
0010FFFF
H
CS1X(64kbyte) CS3X(1Mbyte)
0011FFFF
H
CS2X(64kbyte) 002FFFFF
H
0012FFFF
H
CS3X(64kbyte) CS4X(1Mbyte)
0013FFFF
H
CS4X(64kbyte) 003FFFFF
H
0014FFFF
H
CS5X(64kbyte) CS5X(1Mbyte)
004FFFFF
H
CS0X CS0X
(a) (b)