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SWITCH.DOC
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1989-12-09
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The G8BPQ AX25 Networking Package.
1. Introduction.
This software allows an IBM PC, or similar machine, equiped with suitable
Communications hardware, to act as a Node in a NET/ROM compatible AX25
network, and/or to support a multiuser Mailbox, or other similar applications.
It supports multiple AX25 links, limited only by the connectivity of the
hardware and available storage. The interface to other software in the PC
(Mailbox, application, or other terminal programs) is equivalent to a number
(max 16, but possibly limited by memory requrements) of TNC's, accessed via
the COMBIOS interface. One virtual TNC may be configured to run in a mode
similar to the PK88 Host mode (for use with the UFQ BBS), others provide an
interface similar to the TNC2.
Note the software is NOT Public Domain. It may be used only by licenced
Radio Amateurs in Amateur Packet Radio systems.
2 Hardware Requirements.
The system is written in 8086 assembler, and is currently only available for
the MSDOS/PCDOS environment, although once loaded it makes no use of operating
system facilities. It has been tested on IBM PC and XT machines, and a number
of similar machines. (AST Premium, Toshiba T1100+, OPUS). The software needs
about 48 - 80k RAM, varying with number of buffers, comms links and COMBIOS
ports configured.
Drivers are available for the following comms hardware:
PAC-COM PC120 card
DRSI PCPA card
Software Forge HDLC card for the Toshiba T1100 (with external modem).
KISS mode TNC via a standard PC ASYNC card or QUADRAM Quadport .
Link to NET/ROM or TheNet Async port.
RLC100 4 port HDLC card.
The system has been tested up to 38400 bps on a DRSI card
The software should by modifyable to run on any system with the following:
8086/88/186/286 Processor
64k RAM
32k ROM or Bootstrap ROM plus disk
Timer interrupt with resolution of at most 50ms (better 10ms)
Interrupt driven SCC comms port(s) with suitable modems
3. Networking Facilities.
The system is designed to be operationally compatible with existing NET/ROM
or TheNet nodes, but there are a few minor differences. As it can support
an integrated BBS, it has 2 Callsign/Alias pairs, one for accessing the node,
and the other the BBS. Note, however, that a multiport node does not need a
different callsign for each port. Because of the multiport support, the
'Downlink' connect command needs a port number as the first parameter (eg
C 2 G8BPQ). A connect to another Node doesnt need this - the system selects
the 'best' port as found from the NODEs and ROUTEs lists.
Although multiple applications are allowed, only one (BBS) has its own
Callsign/Alias pair. Others are accessed by connecting to the switch, then
entering the service name.
There are extra commands for normal use (BBS, or other application name, to
connect to the applications, and PORTS to display available port descriptions),
and 2 commands intended primarily for the system operator (STATS and LINKS).
Two extra commands PACLEN and L4T1 are available to set Paclen for NODE
generated messages (nodes lists, etc), and the Transport timeout. At the
moment these are primarily for me to experiment with, but feel free to fiddle.
The system is also able to link to the 'back end' async port on a normal
NET/ROM or TheNet node.
4. Mailbox/Application Support Facilities.
The system may be configured to run multiple copies of WA7MBL/W0RLI/G4YFB
BBS software, (or others designed to talk to a standard TNC using the COMBIOS
interface) running under DesqView, or one copy of G8UFQ or AA4RE BBS,
supporting up to 9 users via a single virtual 'Host Mode' TNC. The Mailbox
callsign and alias are included in 'NODES' broadcasts, allowing level 4
connects direct to the BBS (ie it is not necessary to connect to the node,
then issue a connect to the BBS). The software has recently been tested with
BBS systems written by GW3TMH and G1NNA.
Applications other than BBS must use the COMBIOS interface. (ie not Host Mode).
5. TNC Emulation Facilities.
The Host Mode TNC emulation provides the minimum support necessary for use
with the UFQ BBS.
The TNC2 emulation code accepts the following commands:
CONOK ON/OFF - Indicates the port is available for use. By default, it
will be for the BBS application. See APPL comand.
APPL - Bit significant field, to indicate which application the
port is supporting. The first three are reserved for BBS,
connects to the SYSOP (HOST support), and remote SYSOP
facilities. The other 5 are available for you to define your
own application servers (eg DATABASE, UNIX gateway).
Default is 01, the BBS.
To allow users to connect to you (using the C command
from the switch without a param), set APPL=02, and CONOK ON
BBSMON ON/OFF - Reduces the monitor output to calls only (enough to maintain
the JA list). Place in the MBL config file startup section.
MTX ON/OFF - Monitors transmitted frames - mainly used for debugging
MONITOR ON/OFF - As in normal TNC
MALL ON/OFF
MCOM ON/OFF
MCON ON/OFF Note that to monitor whilst connected to the Node, you
need MCON ON
MMASK - Selects which (radio) ports will be monitored. A bit
significant field - setting bit 0 allows monitoring of
the first port, bit 1 the second, and so on. Default is
hex FF, monitoring all radio ports. Setting it to zero
will suppress all monitoring.
The monitor code will decode and display the network headers from messages
between nodes. This enables you to see what routes are being used between
nodes, as well as removing a lot of garbage from the monitor display!
NOMODE ON/OFF The next 2 are accepted, but are not fully implemented. In
NEWMODE ON/OFF general BBS connects assume NOMODE on, others NOMODE off.
CONNECT
To connect to the node, use the command NODE (or K). This is equivalent to
connecting to a normal node. There is a (roughly) equivalent command
C SWITCH, which returns the string *** CONNECTED to SWITCH, and is used
in MBL forward files, as the MBL software is expecting the first connect
to be at Level 2. A Connect command without a parameter returns the
current state, again mainly for use by MBL software. A connect with any other
parameter connects to the Node, then passes the command to the Node's command
processor, thus allowing you to enter a normal Connect from either TNC or NODE
command level.
CONV
TRANS
UNPROTO CALL [VIA CALL ...]
BTEXT
The CONV and TRANS command enter the appropriate state, and if not connected
to the Node, allow you to send UI frames. This is used for the MBL 'Mail for
xxxx' broadcasts, and can be used for CQ's , etc. Beaconing is not supported,
but the BTEXT text is saved, and may be send instead of the predefined ID
message at intervals. This is primarily for RLI 'MAIL' beacons.
Note that K is an abbreviation for NODE, not CONV, as in a normal TNC, as
normally you want to switch easily between TNC command and Node command modes.
SENDPAC
CPACTIME
CR - As normal TNC.
FLOW ON/OFF - Similar to normal TNC, but a bit simpler. in particular
echoing is suppressed, so if you need to use FLOW ON, I
suggest you set ECHO OFF
John Wiseman, G8BPQ
9 Dec 89.