HT6576A
Address 1: Initiator command register
WRITE
7
6
5
4
ASSERT
RST
TRI–STATE RESERVED
ASSERT
ACK
3
ASSERT
BSY
2
ASSERT
SEL
1
ASSERT
ATN
0
ASSERT
DATA
• BIT 7: ASSERT RST
WHEN SET, THE RST SIGNAL IS ASSERTED ON THE SCSI BUS
• BIT 6: TRI–STATE (TEST MODE)
• BIT 5: RESERVED (0)
• BIT 4: ASSERT ACK
WHEN SET, THE ACK SIGNAL IS ASSERTED ON THE SCSI BUS
• BIT 3: ASSERT BSY
WHEN SET, THE BSY SIGNAL IS ASSERTED ON THE SCSI BUS
• BIT 2: ASSERT SEL
WHEN SET, THE SEL SIGNAL IS ASSERTED ON THE SCSI BUS
• BIT 1: ASSERT ATN
WHEN SET, THE ATN SIGNAL IS ASSERTED ON THE SCSI BUS
• BIT 0: ASSERT DATA
WHEN SET, This bit allows the contents of the output data register to be enabled as chip outputs
on SCSI signal DB0–DB7
READ
7
RET
6
ARBIT
PROGRESS
5
LOST
ARBIT
4
ACK
3
BSY
2
SEL
1
ATN
0
ASSERT
DATA
Address 2: Mode register
READ/WRITE
7
6
5
LOCK
DMA
TARGET ENABLE
MODE PARITY
4
ENABLE
PARITY
3
2
ENABLE
EOP
MONITOR
CHECK
BUSY
1
DMA
IRQ
MODE
• BIT 7: BLOCK MODE DMA
• BIT 6: TARGET MODE
When set, the chip operates as an SCSI bus target device.
• BIT 5: ENABLE PARITY CHECKING
When set, data received on the SCSI data bus is checked for odd parity.
0
ARBIT
4
14th July ’97