39
Pin Name
Pin #
Type
Description
HD15
HD14
HD13
HD12
HD11
HD10
HD9
HD8
HD7
HD6
HD5
HD4
HD3
HD2
HD1
HD0
76
78
80
82
86
88
90
94
95
91
89
87
85
81
79
77
HD7=I/O
Host Data Bus (ATAPI & SCSI DMA Modes)
HWR#/
STOP/
DBWR#
72
I
PU
ATA Write Strobe (ATAPI Mode):
During PIO and DMA transfers, the host
uses this signal to write data to the device.
ATA Stop Ultra DMA Burst (ATAPI Mode):
During Ultra DMA transfers,
the host uses this signal to halt a burst transfer. Bit SUDMA (0C3h.7)
enables UDMA mode.
O
SCSI DMA Write Strobe (SCSI DMA Mode):
The SCSI protocol controller
latches data from the OTI-9797 on the rising edge of DBWR#, which is
driven by the OTI-9797 and derives its timing from the SCSICLK signal.
HRD# /
HDMARDY# /
HSTROBE /
DBRD#
71
I
PU
ATA Read Strobe (ATAPI Mode):
During PIO and DMA transfers, the host
uses this signal to read data from the device.
ATA Ultra DMA Host Ready / Host Data Strobe (ATAPI Mode):
The host
uses this signal to indicate it is ready to begin an Ultra DMA read data
transfer. During an Ultra DMA write transfer, the host uses this signal to
strobe data to the device.
O
SCSI DMA Read Strobe (SCSI DMA Mode):
The OTI-9797 latches data
from the SCSI protocol controller on the rising edge of DBRD#, which is
driven by the OTI-9797 and derives its timing from the SCSICLK signal.
ATAPI/SCSI PASS-THROUGH HOST INTERFECE