User Manual

CompactFlash Memory Card Interface Description
CompactFlash
®
Memory Card Product Manual, Rev. 10.0 © 2002 SANDISK CORPORATION 3-23
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.
Table 3-22. 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
Do not care
Do not 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 Do not care Do not 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 Do not care
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.