Fig. 6.17 Configuration Of Buffer Address Pointer (Bap) - Fujitsu MB90420/5 (A) Series Hardware Manual

MB90420/5 (A) SERIES F
n Buffer address pointer (BAP)
The buffer address pointer (BAP) is a 24-bit register and holds the address used at the next transfer
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performed by EI OS. Each BAP is independent of each EI
data between any address in 16 Mbytes and I/O. When the BF bit (BAP updating/fixing selection bit) of the
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EI OS status register (ISCS) indicates 'updating', BAP changes only in the lower 16 bits (BAPH, BAPL) and
does not change in the upper 8 bits (BAPH). Figure 6.17 shows the configuration of the buffer address
pointer (BAP).
BAP
R/W : Both read and write
X : Undefined
Remarks: 1. The area that can be specified by the I/O address pointer (IOA) is 000000
2. The area that can be specified by the buffer address pointer (BAP) is 000000
3. The maximum transfer count that can be specified by the data counter (DCT) is 65,536 (64
Kbytes).
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MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
bit 23 to bit 16
BAPH
(R/W)

Fig. 6.17 Configuration of Buffer Address Pointer (BAP)

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OS channel, so each EI
bit 15 to bit 8
bit 7 to bit 0
BAPM BAPL
(R/W) (R/W)
6-28
2
OS channel can transfer
Initial value
XXXXXX
B
to 00FFFF .
H H
to FFFFFF .
H H