SCSI Registers
4-61
Registers: 0x34–0x37
Scratch Register A (SCRATCHA)
Read/Write
SCRATCHA
Scratch Register A
[31:0]
This is a general purpose, user-definable scratch pad
register. Apart from CPU access, only register read/write
and Memory Moves into the SCRATCH register alter its
contents. The power-up value of this register is
indeterminate.
A special mode of this register is enabled by setting the
PCI Configuration Info Enable bit in the
register. If this bit is set,
returns bits [31:10] of the PCI
Address Register One (BAR1) (MEMORY)
in bits [31:10].
Bits [9:0] of SCRATCH A will always return zero in this
mode. Writes to the SCRATCHA register are unaffected.
Clearing the PCI Configuration Info Enable bit causes the
SCRATCH A register to return to normal operation.
Register: 0x38
DMA Mode (DMODE)
Read/Write
BL[1:0]
Burst Length
[7:6]
These bits control the maximum number of Dwords
transferred per bus ownership, regardless of whether the
transfers are back-to-back, burst, or a combination of
both. This value is also independent of the width (64-bit
or 32-bit) of the data transfer on the PCI bus. The
LSI53C1000 asserts the Bus Request (PCIREQ/) output
when the DMA FIFO can accommodate a transfer of at
least one burst threshold of data. Bus Request
(PCIREQ/) is also asserted during start-of-transfer and
31
0
SCRATCHA
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
7
6
5
4
3
2
1
0
BL[1:0]
SIOM
DIOM
ERL
ERMP
BOF
MAN
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...