Registers: 0x3C–0x3F

Adder Sum Output (ADDER)

Read Only

31

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ADDER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

0

0

0

0

0

0

 

0

0

0

0

0

0

0

0

 

0

0

 

0

0

 

0

0

0

0

0

0

0

 

0

0

0

0

 

0

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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. It is used to

 

 

 

 

 

 

 

 

 

 

 

 

 

 

determine if the correct memory address was calculated

 

 

 

 

 

 

 

 

 

 

 

 

 

for a relative jump SCRIPTS instruction.

 

 

 

 

 

 

 

 

Register:

0x40

 

 

 

 

 

 

 

SCSI Interrupt Enable Zero (SIEN0)

 

 

 

 

Read/Write

 

 

 

 

 

 

 

7

 

6

 

5

4

 

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

M/A

 

CMP

 

SEL

RSL

 

SGE

UDC

RST

PAR

 

 

 

 

 

 

 

 

 

 

 

0

 

0

 

0

0

 

0

0

0

0

 

 

 

 

 

 

 

 

 

 

 

This register contains the interrupt mask bits corresponding to the interrupting conditions described in the SCSI Interrupt Status Zero (SIST0) register. An interrupt is masked by clearing the appropriate mask bit. For more information on interrupts, see Chapter 2, “Functional Description.”

M/ASCSI Phase Mismatch - Initiator Mode;7 SCSI ATN Condition - Target Mode

In the initiator mode, this bit is set when the SCSI phase asserted by the target and sampled during SREQ/ does not match the expected phase in the SCSI Output Control Latch (SOCL) register. This expected phase is automatically written by SCSI SCRIPTS. In target mode, this bit is set when the initiator asserts SATN/. See the Disable Halt on Parity Error or SATN/ Condition bit in the SCSI Control One (SCNTL1) register for more information on when this status is actually raised.

SCSI Registers

4-73

Page 165
Image 165
LSI 53C875A technical manual Registers 0x3C-0x3F, 0x40, Adder