4-68
Registers
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, the
register returns bits [31:10] of the PCI
Base Address Register One (MEMORY)
in bits [31:10] of
the SCRATCH A register when read. 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
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 or
32 bits) of the data transfer on the PCI bus. The
LSI53C896 SCSI function asserts the Bus Request
(REQ/) output when the DMA FIFO can accommodate a
transfer of at least one burst threshold of data. Bus
31
0
SCRATCHA
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
7
6
5
4
3
2
1
0
BL
SIOM
DIOM
ERL
ERMP
BOF
MAN
0
0
0
0
0
0
0
0
*
Содержание LSI53C896
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 88: ...2 62 Functional Description...
Страница 112: ...3 24 Signal Descriptions...
Страница 306: ...6 38 Specifications This page intentionally left blank...
Страница 310: ...6 42 Specifications This page intentionally left blank...
Страница 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Страница 340: ...6 72 Specifications...
Страница 346: ...A 6 Register Summary...
Страница 362: ...IX 12 Index...