4-72
Registers
Register: 0x42
SCSI Interrupt Status Zero (SIST0)
Read Only
Reading the
SCSI Interrupt Status Zero (SIST0)
register returns the
status of the various interrupt conditions, whether they are enabled in the
SCSI Interrupt Enable Zero (SIEN0)
register or not. Each bit set indicates
occurrence of the corresponding condition. Reading the SIST0 clears the
interrupt status.
Reading this register clears any bits that are set at the time the register
is read, but does not necessarily clear the register because additional
interrupts may be pending; the LSI53C1000 stacks interrupts. SCSI
interrupt conditions are individually masked through the
register.
When performing consecutive 8-bit reads of the
,
SCSI Interrupt Status Zero (SIST0)
, and
registers (in any order), insert a delay equivalent to 12 clock
periods between the reads to ensure the interrupts clear properly. Also,
if reading the registers when both the
Interrupt Status Zero (ISTAT0)
SIP
and DIP bits may not be set, read the SIST0 and SIST1 registers before
the DSTAT register to avoid missing a SCSI interrupt. For more
information on interrupts refer to
Chapter 2, “Functional Description.”
M/A
Initiator Mode: Phase Mismatch; Target Mode:
SATN/ Active
7
In the initiator mode, this bit is set if the SCSI phase
asserted by the target does not match the instruction.
The phase is sampled when SREQ/ is asserted by the
target. In the target mode, this bit is set when the SATN/
signal is asserted by the initiator.
CMP
Function Complete
6
This bit is set when an arbitration only or full arbitration
sequence is completed.
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
Содержание LSI53C1000
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 28: ...1 12 Introduction...
Страница 234: ...4 124 Registers...
Страница 314: ...6 40 Specifications This page intentionally left blank...
Страница 318: ...6 44 Specifications This page intentionally left blank...
Страница 344: ...6 70 Specifications This page intentionally left blank...
Страница 350: ...6 76 Specifications Figure 6 42 LSI53C1000 329 Ball Grid Array Bottom view...
Страница 352: ...6 78 Specifications...
Страница 360: ...A 8 Register Summary...
Страница 376: ...IX 12 Index...