SMC Networks SMC91C95 User Manual

Page 39

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39

BANK SELECT REGISTER

OFFSET

NAME

TYPE

SYMBOL

E

BANK SELECT

REGISTER

READ/WRITE

BSR

HIGH

BYTE

0

0

1

1

0

0

1

1

0

0

1

1

0

0

1

1

LOW

BYTE

BS2

BS1

BS0

X

X

X

X

X

0

0

0

BS2, BS1, BS0 - Determine the bank presently in
use.

The BANK SELECT REGISTER is always
accessible except in PCMCIA powerdown mode
and is used to select the register bank in use.

The upper byte always reads as 33h and can be
used to help determine the I/O location of the
SMC91C95.

The BANK SELECT REGISTER is always
accessible regardless of the value of BS0-BS2.

The SMC91C95 implements only four banks in
ISA mode, therefore, accesses to non-existing
banks (BS2=1) are ignored. All six banks are
accessible in PCMCIA mode.

BS2

BS1

BS0

BANK#

0
0
0
0
1

0
0
1
1

X

0
1
0
1

X

0
1
2
3

None

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