4-40
Registers
REQ
SREQ/ Status
7
ACK
SACK/ Status
6
BSY
SBSY/ Status
5
SEL
SSEL/ Status
4
ATN
SATN/ Status
3
MSG
SMSG/ Status
2
C_D
SC_D/ Status
1
I_O
SI_O/ Status
0
Register: 0x0C
DMA Status (DSTAT)
Read Only
Reading this register clears any bits that are set at the time the register
is read, but does not necessarily clear the register in case additional
interrupts are pending (the LSI53C895A stacks interrupts). The DIP bit
in the
Interrupt Status Zero (ISTAT0)
register is also cleared. It is possible
to mask DMA interrupt conditions individually through the
register.
When performing consecutive 8-bit reads of the DSTAT,
and
SCSI Interrupt Status One (SIST1)
registers (in
any order), insert a delay equivalent to 12 CLK periods between the
reads to ensure that the interrupts clear properly. See
for more information on interrupts.
DFE
DMA FIFO Empty
7
This status bit is set when the DMA FIFO is empty. It is
possible to use it to determine if any data resides in the
FIFO when an error occurs and an interrupt is generated.
This bit is a pure status bit and does not cause an
interrupt.
7
6
5
4
3
2
1
0
DFE
MDPE
BF
ABRT
SSI
SIR
R
IID
1
0
0
0
0
0
x
0
Содержание LSI53C895A
Страница 1: ...S14028 B LSI53C895A PCI to Ultra2 SCSI Controller TECHNICAL MANUAL A p r i l 2 0 0 1 Version 2 2...
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 222: ...4 114 Registers...
Страница 260: ...5 38 SCSI SCRIPTS Instruction Set...
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