Specifications

3.1 Signal / Pin descriptions
Note. Not all Seagate drives support the full complement of ATA signals
listed below. To determine the complete set of signals that are
supported by a particular Seagate drive, see the product manual
for that drive.
Pin # Signal name Description
01 RESET– Reset signal from the host.
02 Ground Grounding pin
03–18 Host Data 0
through
Host Data 15
Data lines to and from host. These comprise
the 16-bit tristate, bidirectional data bus
between host and drive. The lower 8-bits of
host data (0–7) are used for register and ECC
access. All 16 bits are used for data transfers.
19 Ground Grounding pin
20 Key An unused pin, which is clipped off at the
drive to allow keyed cable attachment.
21 DMARQ DMA Request (optional)
22 Ground Grounding pin
23 DIOW– Drive I/O write strobe. Rising edge clocks
data from the host data bus to a drive register
or data port.
24 Ground Grounding pin
25 DIOR– Drive I/O read strobe. Falling edge enables data
from a drive register or data port to host data bus.
26 Ground Grounding pin
27 IORDY I/O Channel Ready (optional); a tristate signal.
28 SPSYNC
or
CSEL
(optional) SPSYNC is an interdrive clock
signal sent from the master drive to the slave
drive to allow the slave to synchronize its
spindle motor to the master drive’s spindle
motor. CSEL is used to differentiate master
from slave in a two-drive system.
29 DMACK– DMA Acknowledge (optional)
30 Ground Grounding pin
10 ATA Interface Reference Manual, Rev. C