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Response id one (respid1), Register: 0x4b (0xcb), Register: 0x4c (0xcc) – Avago Technologies LSI8751D User Manual

Page 186

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5-70

SCSI Operating Registers

Register: 0x4B (0xCB)

Response ID One (RESPID1)
Read/Write

RESPID1

Response ID One

[15:8]

RESPID0 and RESPID1 contain the selection or
reselection IDs. In other words, these two 8-bit registers
contain the ID that the chip responds to on the SCSI bus.
Each bit represents one possible ID with the most
significant bit of RESPID1 representing ID 15 and the
least significant bit of RESPID0 representing ID 0. The

SCSI Chip ID (SCID)

register still contains the chip ID

used during arbitration. The chip can respond to more
than one ID because more than one bit can be set in the

Response ID One (RESPID1)

and

Response ID Zero

(RESPID0)

registers. However, the chip can arbitrate with

only one ID value in the

SCSI Chip ID (SCID)

register.

Register: 0x4C (0xCC)

SCSI Test Zero (STEST0)
Read Only

SSAID

SCSI Selected As ID

[7:4]

These bits contain the encoded value of the SCSI ID that
the LSI53C875 is selected or reselected as during a
SCSI selection or reselection phase. These bits are read
only and contain the encoded value of 0–15 possible IDs
that are used to select the LSI53C875. During a SCSI
selection or reselection phase, when a valid ID has been
put on the bus, and the LSI53C875 responds to that ID,
the “selected as” ID is written into these bits. These bits
are used with the RESPID registers to allow response to
multiple IDs on the bus.

15

8

ID

x

x

x

x

x

x

x

x

7

4

3

2

1

0

SSAID

SLT

ART

SOZ

SOM

0

0

0

0

0

x

1

1

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