NTWO(4) BSD Programmer's Manual NTWO(4)NAMEntwo - SDL Communications RISCom/N2 high-speed synchronous interface
SYNOPSIS
ntwo0 at isa? port 0x220 iomem 0xe0000 iosiz 32768
ntwo0 at pci?
DESCRIPTION
The ntwo interface provides two point-to-point bit-synchronous serial
connections with speeds up to 5 Mb/s using HDLC frame format. Both ISA
and PCI bus interface versions are supported. All boards have two chan-
nels although some may have one channel de-populated. ISA boards use a
switch-selectable block of 8 I/O ports in the range 0x200 through 0x3f0.
The block must be aligned on a 16 port boundary. The jumper-selectable
interrupt level is detected at auto-configuration time or alternatively
can be specified in the system configuration file. Supported IRQs are:
3, 4, 5, 10, 11, 12 and 15. ISA boards require a 32, 64, or 256 Kb I/O
memory window aligned at a 16 KB boundary (the base address and size
should be specified in the system configuration file). The window size
should be set equal to half the memory on the board; this is because the
two channels on the board are only mapped one at a time. ISA boards
should be installed in a 16-bit slot.
PCI boards use the PCI bus mechanism to configure their IRQ and base ad-
dress. Some systems require a separate PCI BIOS configuration menu be run
to configure each bus slot. System memory is used by the PCI board and
the amount may be specified in the system configuration file. The default
is 128Kb with the memory divided evenly between the two channels on the
board. PCI boards have pluggable front-end physical interfaces.
Supported synchronous serial encapsulation protocols are described in
p2p(4).
VARIATIONS
The following variations of the ISA version of this board are currently
supported:
N2 This is the standard two channel card. These are up to T1 speed
DSU ports.
N2S This is the standard card with only one set of drivers/receivers
populated. There is no reasonable way to tell the two cards apart.
Therefore the single channel card will show up with two channels,
only the first of which is operational.
N2CSU This is a dual channel card. The first channel is the same as
found on other N2 cards. The second channel is a T1 port with a
built-in CSU. The CSU requires initialization before the channel
can be utilized (see n2setup(8)).
The built-in CSU will switch to loopback mode upon receipt of loop
up codes from the network provider. Loopback mode is indicated by
the status lights described below.
The N2CSU card has four status lights which indicate the status of
the built-in CSU on the second channel (from top to bottom):
Color Description
RED Loss of Signal if on steady
RED Loss of Frame if on steady
AMBER Loopback mode if on steady
GREEN Firmware running if flashing
N2DDS This is a dual channel card. The first channel is the same as
found on other N2 cards. The second channel has a 56K CSU built-
in. The CSU requires initialization before the channel can be uti-
lized (see n2setup(8)).
The CSU will switch to loopback mode upon receipt of reversed
ceiling current from the network provider. Loopback mode is indi-
cated by the status lights described below.
The N2DDS card has four status lights which indicate the status of
the built-in CSU on the second channel (from top to bottom):
Color Description
RED Receive Loss of Signal if on steady
RED Not Used
AMBER Loopback mode if on steady
GREEN Firmware running if flashing
The RISCom/N2pci is a dual channel card with pluggable front-end physical
interfaces. The following front-end types are currently supported:
N2RS232 This front-end interface has RS-232 drivers and receivers.
N2RS422 This front-end interface has RS-422 drivers and receivers.
N2V35 This front-end interface has V.35 drivers and receivers.
FLAGS
While setting parameters via the flags field is still supported the
n2setup(8) program is the preferred method. Configuration flags are used
to ignore DCD, become quiet about data line errors, and gate the receive
clock to the transmit clock. The low order 16 bits (0xffff) are used for
channel 0 and the high order 16 bits (0xffff0000) for channel 1. Current-
ly only 3 bits from each half are used. The low order bit (0x00010001)
is used to ignore DCD on the respective channel. The next bit
(0x00020002) is used to cause the driver to be silent about communication
errors. The final bit (0x00040004) gates the receive clock to the trans-
mit clock, this is needed with X.21 modems using standard cables rather
than the SDL specified cross over cables.
SEE ALSOintro(4), inet(4), p2p(4), ifconfig(8), n2setup(8)BSDI BSD/OS June 28, 1996 2
