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Bit bus width – FUJITSU MB91460 SERIES FR60 User Manual

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Chapter 31 External Bus

4.Endian and Bus Access

Figure 4-16 Relationship between Internal Register and External Data Bus for Byte Access

Data Bus Width

The following shows the relationships between the internal register and external data bus for each data bus width.

32-bit bus width

Figure 4-17 Relationship between Internal Register and External Bus Data for 32-bit Bus Width

16-bit bus width

Figure 4-18 Relationship between Internal Register and External Bus Data for 16-bit Bus Width

D31

D15

D23

D7

D0

AA

D31

D15

D23

D7

D0

AA

D31

D15

D23

D7

D0

AA

D31

D15

D23

D7

D0

AA

D31

D15

D23

D7

D0

AA

D31

D15

D23

D7

D0

AA

D31

D15

D23

D7

D0

AA

D31

D15

D23

D7

D0

AA

(3) Halfword access (when executing the LDUB/STB instructions)

a) Output address b) Output address c) Output address d) Output address
low-orderdigits "00" low-order digits "01" low-order digits "10" low-order digits "11"

Internal External Internal External Internal External Internal External
register bus register bus register bus register bus

D07

D15

D23

D31

External bus

Internal resistor

AA

BB

CC

DD

Read/Write

DD

CC

BB

AA

D07

D15

D23

D31

D07

D15

D23

D31

D23

D31

"00" "10"

External bus

Internal register

Output address low-order digits

AA

BB

CC

DD

BB

AA

DD

CC

read/write