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4.5
I/O Transfer Function
4.5.1
I/O Function
The I/O transfer to or from the SDP3B FlashDisk
can be either 8 or 16 bits. When a 16-bit accessible
port is addressed, the signal -IOIS16 is asserted
by the SDP3B FlashDisk. Otherwise, the -IOIS16
signal is de-asserted. When a 16 bit transfer is
attempted, and the -IOIS16 signal is not asserted
by the SDP3B FlashDisk, the system must
generate a pair of 8-bit references to access the
word's even byte and odd byte. The SDP3B
Table 4-15 I/O Function
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)
SanDisk SDP3B FlashDisk Product Manual © 1998 SANDISK CORPORATION
-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
SDP3B FlashDisk Product Manual
FlashDisk permits both 8- and 16-bit accesses to
all of its I/O addresses, so -IOIS16 is asserted for
all addresses to which the SDP3B FlashDisk
responds.
The SDP3B FlashDisk 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.
A0
- I O R D
- I O W R
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
Don't Care
Even-Byte
Don't Care
Odd-Byte
Odd-Byte
Even-Byte
Odd-Byte
Even-Byte
Don't Care
Don't Care
High Z
High Z
Odd-Byte
High Z
Odd-Byte
Don't Care
43
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