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3.5.1. I/O Function
The I/O transfer to or from the CompactFlash Memory Card can be either 8 or 16 bits. When a 16-bit accessible port
is addressed, the signal -IOIS16 is asserted by the CompactFlash Card. Otherwise, the -IOIS16 signal is de-asserted.
When a 16-bit transfer is attempted, and the -IOIS16 signal is not asserted by the CompactFlash Card, the system
must generate a pair of 8-bit references to access the word's even byte and odd byte. The CompactFlash Card
permits both 8 and 16 bit accesses to all of its I/O addresses, so -IOIS16 is asserted for all addresses to which the
CompactFlash Card responds.
Function Code
Standby Mode
Byte Input Access (8 bits)
Byte Output Access (8 bits)
Word Input Access (16 bits)
Word Output Access (16 bits)
I/O Read Inhibit
I/O Write Inhibit
High Byte Input Only (8 bits)
High Byte Output Only (8 bits)
3.6. Common Memory Transfer Function
This section contains valuable information o n the Common Memory Transfer function.
3.6.1. Common Memory Function
The Common Memory transfer to or from the CompactFlash Memory Card can be either 8 or 16 bits.
The CompactFlash Memory Card permits both 8 and 16 bit accesses to all of its Common Memory address es.
®
CompactFlash
Memory Card Product Manual, Rev. 10.0 © 2002 SANDISK CORPORATION
Table 3-22. I/O Function
-REG
-CE2
-CE1
X
H
H
L
H
L
L
H
L
L
H
L
L
H
L
L
L
L
L
L
L
H
X
X
H
X
X
L
L
H
L
L
H
CompactFlash Memory Card Interface Description
A0
-IORD
-IOWR
X
X
X
L
L
H
H
L
H
L
H
L
H
H
L
L
L
H
L
H
L
X
L
H
X
H
L
X
L
H
X
H
L
D15-D8
D7-D0
High Z
High Z
High Z
Even-Byte
High Z
Odd-Byte
Do not care
Even-Byte
Do not care
Odd-Byte
Odd-Byte
Even-Byte
Odd-Byte
Even-Byte
Do not care
Do not care
High Z
High Z
Odd-Byte
High Z
Odd-Byte
Do not care
3-23
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