Dma mode (dmode), Scratch register a (scratcha), Register: 0x38 – Avago Technologies LSI53C1010R User Manual
Page 181
SCSI Registers
4-63
Version 2.2
Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
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
Base Address Register One (BAR1) (MEMORY)
in bits [31:10]. Bits [9:0] of SCRATCH A always returns
zero in this mode. Writes to the SCRATCHA register have
no effect. 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
LSI53C1010R SCSI function asserts the Bus Request
(PCIREQ/) output when the DMA FIFO can
accommodate a transfer of at least one burst threshold of
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