SCSI Registers
4-21
Register: 0x00
SCSI Control Zero (SCNTL0)
Read/Write
ARB[1:0]
Arbitration Mode Bits 1 and 0
[7:6]
Simple Arbitration
1.
The LSI53C896 SCSI function waits for a bus free
condition to occur.
2.
It asserts SBSY/ and its SCSI ID (contained in the
register) onto the SCSI bus. If
the SSEL/ signal is asserted by another SCSI
device, the LSI53C896 SCSI function deasserts
SBSY/, deasserts its ID and sets the Lost Arbitration
bit (bit 3) in the
register.
3.
After an arbitration delay, the CPU should read the
register to check if a
higher priority SCSI ID is present. If no higher
priority ID bit is set, and the Lost Arbitration bit is not
set, the LSI53C896 SCSI function wins arbitration.
4.
Once the LSI53C896 SCSI function wins arbitration,
SSEL/ must be asserted using the
for a bus clear plus a bus
settle delay (1.2
µ
s) before a low level selection is
performed.
7
6
5
4
3
2
1
0
ARB[1:0]
START
WATN
EPC
R
AAP
TRG
1
1
0
0
0
x
0
0
ARB1
ARB0
Arbitration Mode
0
0
Simple arbitration
0
1
Reserved
1
0
Reserved
1
1
Full arbitration, selection/reselection
*
Summary of Contents for LSI53C896
Page 6: ...vi Preface...
Page 16: ...xvi Contents...
Page 88: ...2 62 Functional Description...
Page 112: ...3 24 Signal Descriptions...
Page 306: ...6 38 Specifications This page intentionally left blank...
Page 310: ...6 42 Specifications This page intentionally left blank...
Page 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Page 340: ...6 72 Specifications...
Page 346: ...A 6 Register Summary...
Page 362: ...IX 12 Index...