AT INTERFACE DESCRIPTION
5 – 2
Pin Description TablePin Description TablePin Description TablePin Description TablePin Description TablePIN NAME PIN I/O SIGNAL NAME SIGNAL DESCRIPTION
RESET - 01 I Host Reset Reset signal from the host system. Active during power up and inactive after.
DD0 17 I/O Host Data Bus 16 bit bi-directional data bus between host and drive. Lower 8 bits used for
register and ECC byte transfers. All 16 bits used for data transfers.
DD1 15 I/O
DD2 13 I/O
DD3 11 I/O
DD4 09 I/O
DD5 07 I/O
DD6 05 I/O
DD7 03 I/O
DD8 04 I/O
DD9 06 I/O
DD10 08 I/O
DD11 10 I/O
DD12 12 I/O
DD13 14 I/O
DD14 16 I/O
DD15 18 I/O
DMARQ 21 O DMA Request This signal is used with DMACK for D MA transfers . B y asser ting this s ignal, the
drive indicates that data i s r e ady to be transfered to and from the host.
DIOW -
STOP 23 I Host I/O Write Rising edge of Write strobe clocks data from the host data bus to a register on
the drive.
DIOR -
HDMARDY
-
HSTROBE
25 I Host I/O Read Read strobe enables data from a register on the drive onto the host data bus.
DMA ready during UltraDMA data in bursts.
Data strobe during UltraDMA data out bursts.
IORDY
DDMARDY
-
DSTROBE
27 O I/O Channel Ready This signal may be driven low by the drive to insert wait states into host I/O
cycles.
DMA ready during UltraDMA data out bursts.
Data strobe during UltraDMA data in bursts.
CSEL 28 C able S e lect Used for Master/Slave selection via cable. Requires special cab ling o n host
system and installation of Cable Select jumper.
DMACK - 29 I DMA Acknowledge This signal is used with DMARQ for DMA transfers. By asserting this signal, the
host is acknowledging the receipt of data or is indicating that data is available.
INTRQ 31 O H os t Int er rup t
Request Interrupt to the host asserted when the drive requires attention from the host.
IOCS16 32 Device 16 bit I/O Obsolete
PDIAG - 34 I/O Passed Diagnostic Output by drive when in Slave mode; Input to drive when in Master mode.
DA0 35 I Host Address Bus 3 bit binary address from the host to select a register in the drive.
DA1 33 I
DA2 36 I
CS0 - 37 I Host Chip Select 0 C hip sel ect fro m the host used to a ccess the C ommand Block registers in the
drive. T hi s sig na l is a d ecode o f I/O ad dresses 1F0 - 1F7 he x.
CS1 - 38 I Host Chip Select 1 Chip sele ct from the host used to acce ss the Co ntrol registe rs in the d rive. This
signal is a decode of I/O addresses 3F6 - 3F7 hex.
DASP - 39 I/O Drive Active/Drive
1 Present Time-multiplexed, open collector output which indicates that a drive is active, or
that
device 1 is present.
GND 02 N/A Ground Signal ground.
19
22
24
26
30
40
KEY 20 N/A K ey Pin us e d for k e ying the i nterfa c e connec t or .