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Avago Technologies LSI53C1010R User Manual

Page 282

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5-34

SCSI SCRIPTS Instruction Set

Version 2.2

Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.

CD

Compare Data

18

When this bit is set, the first byte received from the SCSI
data bus (contained in the

SCSI First Byte Received (SFBR)

register) is compared

with the Data to be Compared Field in the Transfer Control
instruction. The Wait for Valid Phase bit controls when this
compare occurs. The Jump if True/False bit determines
the condition (true or false) to branch on.

CP

Compare Phase

17

When the LSI53C1010R is in the initiator mode, this bit
controls phase compare operations. When this bit is set,
the SCSI phase signals (latched by SREQ/) are compared
to the Phase Field in the Transfer Control instruction. If
they match, the comparison is true. The Wait for
Valid Phase bit controls when the compare occurs. When
the LSI53C1010R is operating in the target mode and this
bit is set, it tests for an active SCSI SATN/ signal.

VP

Wait for Valid Phase

16

If the Wait for Valid Phase bit is set, the LSI53C1010R
waits for a previously unserviced phase before comparing
the SCSI phase and data.

If the Wait for Valid Phase bit is cleared, the LSI53C1010R
compares the SCSI phase and data immediately.

MC

Data Compare Mask

[15:8]

The Data Compare Mask allows a SCRIPT to test certain
bits within a data byte. During the data compare, if any
mask bits are set, the corresponding bit in the

SCSI First Byte Received (SFBR)

data byte is ignored.

For instance, a mask of 0b01111111 and data compare
value of 0b1XXXXXXX allows the SCRIPTS processor to
determine whether or not the high order bit is set while
ignoring the remaining bits.

Bit 19

Result of
Compare

Action

0

False

Jump Taken

0

True

No Jump

1

False

No Jump

1

True

Jump Taken