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DISK DRIVE OPERATION
SpinPoint V40 Product Manual
94
6.7.3 Multiword DMA data transfer
Figure 6-3 defines the timings associated with Multiword DMA transfers.
For Multiword DMA modes 1 and above, the minimum value of t
0
is specified by word 65 in the IDENTIFY
DEVICE parameter list. Table 6-18 defines the minimum value that shall be placed in word 65.
Devices shall power up with mode 0 as the default Multiword DMA mode.
NOTE −
1 To prevent the transmission of another word of data, the Device shall negate DMARQ within the t
L
specified time once DMACK- is asserted and reassert it again at a later time to resume the DMA
operation. Alternatively, if the device is able to continue the transfer of data, the device may leave
DMARQ asserted and wait for the host to reassert DMACK-.
2 This signal may be negated by the Host to suspend the DMA transfer in process.
3 This figure shows the transfer of two words. The actual transfer for a given assertion of DMARQ ma
y
be any number of words from one to the remaining number of words to be transferred.
t
H
t
G
Write
DD(15:0)
t
F
t
G
Read
DD(15:0)
t
Z
t
E
DIOR-/DIOW-
t
J
t
K
t
D
t
I
DMACK-
(See note 2)
t
L
DMARQ
(See note 1)
t
0
t
N
t
M
CS0-/CS1-
Figure 6-3 Multiword DMA data transfer