
SCSI Registers
5-51
CIO
Congured as I/O (Read only)
5
This bit is dened as the Conguration I/O Enable Status
bit. This read-only bit indicates if the chip is currently
enabled as I/O space.
Note:
Both bits 4 and 5 may be set if the chip is dual mapped.
CM
Congured as Memory (Read only)
4
This bit is dened as the conguration memory enable
status bit. This read-only bit indicates if the chip is cur-
rently enabled as memory space.
Note:
Both bits 4 and 5 may be set if the chip is dual-mapped.
BSRTCH
SCRATCHA/B Operation
33
This bit controls the operation of the SCRATCHA and
SCRATCHB registers. When it is set, SCRATCHB
contains the RAM base address value from the PCI
Conguration RAM Base address Register. This is the
base address for the 4 Kbytes internal RAM. In addition,
the SCRATCHA register displays the memory-mapped
based address of the chip operating registers. When this
bit is clear, the SCRATCHA and SCRATCHB registers
return to normal operation.
Bit 3 is the only writable bit in this register. All other bits
are read only. When modifying this register, all other bits
must be written to zero. Do not execute a Read-Modify-
Write to this register.
TEOP
SCSI True End of Process (Read only)
2
This bit indicates the status of the SYM53C895 internal
TEOP signal. The TEOP signal acknowledges the
completion of a transfer through the SCSI portion of the
SYM53C895. When this bit is set, TEOP is active. When
this bit is clear, TEOP is inactive.
DREQ
Data Request Status (Read only)
1
This bit indicates the status of the SYM53C895 internal
Data Request signal (DREQ). When this bit is set, DREQ
is active. When this bit is clear, DREQ is inactive.
DACK
Data Acknowledge Status (Read only)
0
This bit indicates the status of the SYM53C895 internal
Data Acknowledge signal (DACK/). When this bit is set,
DACK/ is inactive. When this bit is clear, DACK/ is active.