SanDisk CompactFlash, Руководство по эксплуатации продукта

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CompactFlash Memory Card Product Manual
SanDisk CompactFlash Memory Card Product Manual © 1998 SANDISK CORPORATION 43
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 - R E G - C E 2 - C E 1 A0 - I O R D - I O W R 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
A c c e s s
(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
A c c e s s
( 1 6 b i t s ) L L L L L H Odd-Byte Even-Byte
Word Output
A c c e s s
( 1 6 b i t s ) 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