Product manual

Preliminary CompactFlash Memory Card Product Manual
SanDisk CompactFlash Memory Card Product Manual Rev. 8 © 2001 SANDISK CORPORATION
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4.5 I/O Transfer Function
4.5.1 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.
The CompactFlash Memory Card may request the
host to extend the length of an input cycle until
data is ready by asserting the -WAIT signal at the
start of the cycle.
Table 4-15 I/O Function
Function Code -REG -CE2 -CE1 A0 -IORD -IOWR D15-D8 D7-D0
Standby Mode
X H H X X X High Z High Z
Byte Input Access
(8 bits)
L
L
H
H
L
L
L
H
L
L
H
H
High Z
High Z
Even-Byte
Odd-Byte
Byte Output Access
(8 bits)
L
L
H
H
L
L
L
H
H
H
L
L
Don't Care
Don't Care
Even-Byte
Odd-Byte
Word Input Access
(16 bits)
L L L L L H Odd-Byte Even-Byte
Word Output Access
(16 bits)
L L L L H L Odd-Byte Even-Byte
I/O Read Inhibit
H X X X L H Don't Care Don't Care
I/O Write Inhibit
H X X X H L High Z High Z
High Byte Input Only
(8 bits)
L L H X L H Odd-Byte High Z
High Byte Output Only
(8 bits)
L L H X H L Odd-Byte Don't Care