Technical data

SunOS 5.5 Devices ncrs(7D)
NAME ncrs − low-level module for NCR 53C710, 53C810, 53C815, 53C820, and 53C825 host bus
adapters
SYNOPSIS ncrs@ioaddr,0
AVAILABILITY x86
DESCRIPTION The ncrs module provides low-level interface routines between the common disk/tape
I/O subsystem and the NCR 53C710, 53C810, 53C815, 53C820, and 53C825 SCSI (Small
Computer System Interface) controllers.
The ncrs module can be configured for disk and streaming tape support for one or more
host bus adapter boards. Each host bus adapter board must be the sole initiator on a SCSI
bus. Auto configuration code determines if the adapter is present at the configured
address and what types of devices are attached to it.
The WideSCSI Bus option (16 bit) on adapters using the 53C820 and 53C825 is not sup-
ported. These adapters are operated in their 53C810 compatible mode.
CONFIGURATION The driver attempts to initialize itself in accordance with the information found in the
configuration file, ncrs.conf. The relevant user configurable items in this file are as fol-
lows:
reg This represents the slot id. The slot id corresponds to the PCI (Peri-
pheral Component Interconnect) hardware slot assigned to the
53C8xx adapter or the EISA base address assigned to the 53C710
adapter.
reg consists of a 3-tuple of integers. The first integer is a unique
identifier for this device. The second and third integer are nor-
mally 0. See sysbus(4).
scsi-initiator-id The initiator target id is used by the adapter to communicate with
devices on theSCSI bus. It must not conflict with any target id
value assigned to any disk, tape, or other SCSI devices connected to
the adapter. The valid values are 0 to 7. If this property is omitted
or if the value isn’t valid, the adapter will use target id 7 by
default.
clock The synchronous I/O clock frequency. The clock frequency pro-
perty should match the frequency of the oscillator used to drive
the adapter. All the existing implementations use a 40 Mhz clock.
However, values between 16 and 75 can be specified. If this pro-
perty is omitted or if the value specified is less than 16 or greater
than 75, theSCSI bus will operate in AsynchronousI/O mode.
max-sync-rate The maximum synchronous I/O transfer rate property can be used
to limit the maximum I/O rate for each target device on theSCSI
bus. This property consists of a comma separated list of values.
The list specifies in order the maximum synchronous I/O rates for
modified 14 Mar 1995 7D-223