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Register: 0x3c–0x3f – Avago Technologies LSI53C876E User Manual

Page 166

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4-72

Registers

other than

Interrupt Status (ISTAT)

, this register cannot

be accessed except by a SCRIPTS instruction during
SCRIPTS execution. For more information on the use of
this bit in interrupt handling, see

Chapter 2, “Functional

Description.”

COM

LSI53C700 Family Compatibility

0

When the COM bit is cleared, the LSI53C876 SCSI
function behaves in a manner compatible with the
LSI53C700 family; selection/reselection IDs are stored in
both the

SCSI Selector ID (SSID)

and

SCSI First Byte

Received (SFBR)

registers. This bit is not effected by a

software reset.

If the COM bit is cleared, do not access this register
using SCRIPTS operation as nondeterminate operations
may occur. (This includes SCRIPTS Read/Write
operations and conditional transfer control instructions
that initialize the

SCSI First Byte Received (SFBR)

register.)

When the COM bit is set, the ID is stored only in the

SCSI Selector ID (SSID)

register, protecting the SFBR

from being overwritten if a selection/reselection occurs
during a DMA register-to-register operation.

Register: 0x3C–0x3F

Adder Sum Output (ADDER)
Read Only

ADDER

Adder Sum Output

[31:0]

This register contains the output of the internal adder,
and is used primarily for test purposes. The power-up
value for this register is indeterminate.

31

0

ADDER

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x