SMCXXXBF Datasheet, PDF (39/91 Pages) STMicroelectronics – 32MByte, 64MByte, 128MByte, 256MByte, 512MByte, 1GByte, 2GByte, and 4GByte 3.3/5V Supply CompactFlash™ Card

SMCxxxBF
Card Configuration
6.6
I/O Transfer Function
The I/O transfer to or from the Card can be either 8 or 16 bits. When a 16 bit accessible
port is addressed, the –IOIS16 signal is asserted by the Card, otherwise it is de-asserted.
When a 16 bit transfer is attempted, and the –IOIS16 signal is not asserted, the system must
generate a pair of 8 bit references to access the Word’s even and odd Bytes. The Card
permits both 8 and 16 bit accesses to all of its I/O addresses, so –IOIS16 is asserted for all
addresses (see Table 33).
.
Table 33. I/O Function
Function Code –REG –CE2 –CE1 A0 –IORD –IOWR D15 to D8
Standby Mode
X
H
HX X
Byte Input Access L
H
LL
L
(8 bits)
L
H
LH L
Byte Output Access L
H
LL
H
(8 bits)
L
H
LH H
Word Input Access
L
L
LL
L
(16 bits)
Word Output Access
L
L
LL
H
(16 bits)
I/O Read Inhibit
H
X
XX
L
I/O Write Inhibit
H
X
XX H
High Byte Input Only
L
L
HX
L
(8 bits)
High Byte Output
Only
L
L
HX H
(8 bits)
X
High Z
H
High Z
H
High Z
L Don’t Care
L Don’t Care
H
Odd Byte
L
Odd Byte
H Don’t Care
L
High Z
H
Odd Byte
L
Odd Byte
D7 to D0
High Z
Even Byte
Odd Byte
Even Byte
Odd Byte
Even Byte
Even Byte
Don’t Care
High Z
High Z
Don’t Care
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