EBTEL Discussion Document 1 - EBTEL.DOCS.Intro01
Update 0.02, Author J.G.Harston, Date 14-01-1997
Since the discussions at the Not The Acorn User Show about setting up a
network system that can be accessed over the telephone, there has been
some discussions about its implementation, and some questions about how it
will work. This introductory discussion document is intended to flesh out
the progress so far and clarify some confusions.
Chris Richardson has suggested that this project be called the EBTEL
network, standing for Eight-Bit TELephone network. This seems reasonable
enough for this particular network and in the absence of any other name,
that's what I'll call it from now on. We'll have to think up a generic
name for this process at some other point. EBTEL is seen as a system
where somebody can dial in to a site and read information presented in a
similar way to the monthly magazine disks, read messages, send messages
and download programs, ideally as part of an automated process so that the
user is using the phone line for as short a period of time as possible.
So far, this is a standard BBS. However, the next step is to make EBTEL
an extension of NFS such that somebody could actually log onto a remote
fileserver and load and save programs, list catalogues, etc., just as
though it was a local disk. That is, EBTEL would form a gateway between
the phone line and a file server at the remote site.
Rather than write some sort of remote access file server program, it is
much more sensible to just write a program that sits between the phone
line and a local Econet system and have any Econet file server plugged
into that Econet. It also doesn't have to be specifically a telephone
connection, just any serial connection connected through the serial port,
so from here on, I'll refer to it as an Econet-Serial Gateway. A bridge,
such as an Econet Bridge, connects two similar networks together, such as
Econet to Econet. A gateway connects two dissimliar networks together,
such as Econet to Ethernet. EBTEL contains an Econet to Serial gateway.
The BBS Part of EBTEL
This stage was already at a quite advanced stage at the NAUS in July when
we started discussing it. I had already written most of a simple BBS
program, but hadn't fully got round to fully implementing it. In the
EBTEL system, the BBS will run in the foreground, and the Econet-Serial
Gateway will run in the background. Any incoming serial data will be
checked to see if it is a network packet, and if so it will be passed on to
the network. Non-network packets will be passed on to the serial input
buffer as normal. Serial output will be transfered from the output buffer
to the serial port as normal. Serial network transmission will send the
packet out through the serial port bypassing the output buffer. As far as
any foreground program (such as the BBS) using the serial I/O routines is
concerned there is no difference.
The actual implementation of the EBTEL BBS is intended to make it as easy
as possible to call in, get any information, and hang up as quickly as
possible so as to reduce the amount of time actually using the phone line.
Answers to Some Questions
Q: Will users of the filing system be able to hook up to any Econet
gateway server on any telephone number? (AGN)
A: Yes, just as a user of NFS with Econet can connect to a file server at
any station on any network.
Q: Will the RNFS have to respond to Econet calls from programs that have
been downloaded from a network via the RNFS? If so how can we make
sure that Econet based programs can run via the link just as if the
user was at a local station on the network? (AGN)
A: The RNFS doesn't respond to Econet calls from programs. It responds to
network calls from the NFS. As far as the program is concerned, it
is just another filing system. Or rather, just another part of the
Q: If someone was logged on to a network via the RNFS or link software and
a program contained a call, say, to read the logged on user name;
the RNFS would have to intercept the call and pass it on to the
file server via the link and NOT send the call to the user's
machine at home!! (am I right????) (AGN)
A: The call to read the logged-on user name is OSWORD &14,32. This is sent
to the current file-server. The NFS doesn't care where the
fileserver is. If the current file-server is one connected by
telephone, it will be sent there.
Q: Could every modem user of 8-Bit Software be given a user area to
receive or send 8-Mail and or to store files etc at a remote
location eg. the 8-Bit Software Econet file server. An example of
this could be that a list of your computer equipment and serial
numbers could be stored so in the event of loss there is still a
copy of the document on the file server. (AGN)
A: Yes, this is just a standard file-server set-up.
Q: It would be excellent if the three of us all had gateway servers on our
Econets then any one with RNFS could just dial up and use The Beeb
Developments Network or The 8-Bit Software Network not to mention
the Harston Econet!! (AGN)
A: Yes, I agree entirely.
Q: Will the Gateway server software be compatible with Acorn or SJ
Research File Servers? (AGN)
Q: No, as I keep saying, it is an alternative network, not a filing
system. What gets sent over the network is irrelevent. Any
program that works correctly with a fileserver connected directly
through a local Econet will work correctly with a remote
Q: Does this mean I will have to spend money on software to let me
connect? Isn't that a bit like Microsoft tying you in to
A: Any standard terminal program will be able to access EBTEL to use it as
a bulletin board; reading and sending messages and downloading and
NETWORK: A network is a system of connecting similar items together.
8-Bit software currently has a postal network of BBC users with a maximum
data transmission rate of about 400k per month. The Econet network uses
ADLC protocols to connect computers together over a five-wire balanced
ADLC: The Advanced Data Link Controller. The IC used in Econet interfaces
for communicating over the network.
Bulletin Board System (BBS): A system that can be dialled into to access
information. Most BBSs include facilities for reading and writing public
information, private messages to other users and files and programs.
BRIDGE: A bridge joins two similar networks together. An Econet bridge
joins two Econet networks together, passing data between each side.
GATEWAY: A gateway joins two dissimilar networks together. Any Archimedes
with an Econet interface and an Ethernet interface can operate as an
NETWORK FILING SYSTEM (NFS): The NFS is the software interface between
programs and networks. It translates, for instance, an OSFILE &FF call to
load a file into the correct calls to the network routines to communicate
with a file server. The NFS in BBC and Master computers can only use the
Econet network. The NFS in Archimedes can currently use Econet or
Ethernet. The important thing is to remember that NFS is concerned with
the file system, not with the hardware or the wires or the file servers.
FILE SERVER: A file server is a shared resource that provides access to
files, and usually some form of access control and protection. File
servers used with BBCs communicate with the Acorn NFS over the Econet.
The NFS in Archimedes knows how to communicate with Acorn NFS Fileservers
and UNIX fileservers, over either Econet or Ethernet.
EBTEL.DOCS.Modems01 Information about modems, choosing them, what to
avoid, how to connect to the BBC, how to test they
work, simple Basic terminal program
EBTEL.DOCS.Net01 How networks communicate, and how they are
connected together to form larger networks.
0.01 16-10-1996 Initial draft covering everything
0.02 14-01-1997 Moved specific details to separate files; this version
delayed due to the author's arduous work schedule.