SCSI Registers
4-67
STD
Start DMA Operation
2
The LSI53C1000 fetches a SCSI SCRIPTS instruction
from the address contained in the
register when this bit is set. This bit is required if
the LSI53C1000 is in one of the following modes:
•
Manual start mode – Bit 0 in the
register is set
•
Single-step mode – Bit 4 in the
register is set
When the LSI53C1000 is executing SCRIPTS in manual
start mode, the Start DMA bit must be set to start
instruction fetches, but need not be set again until an
interrupt occurs. When the LSI53C1000 is in the
single-step mode, set the Start DMA bit to restart
execution of SCRIPTS after a single-step interrupt.
R
Reserved
1
COM
LSI53C700 Family Compatibility
0
When the COM bit is cleared, the LSI53C1000 behaves
in a manner compatible with the LSI53C700 family;
selection/reselection IDs are stored in both the
and
SCSI First Byte Received (SFBR)
registers. This bit is not affected by a software reset.
If the COM bit is cleared, do not access this register
using SCRIPTS operation as indeterminate 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
register, protecting the
from being overwritten if a
selection/reselection occurs during a DMA register-to-
register operation.
Содержание LSI53C1000
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 28: ...1 12 Introduction...
Страница 234: ...4 124 Registers...
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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...