Path: utzoo!attcan!uunet!mcvax!unido!infbs!hafer
From: hafer@infbs (Udo Hafermann)
Newsgroups: comp.sys.atari.st
Subject: Re: mx2v230 (in comp.binaries/sources.atari.st)
Summary: There is at least *one* operational Atari network
Keywords: Atari ST Networks
Message-ID: <116@infbsgr.infbs>
Date: 4 Jan 89 13:43:54 GMT
References: <5860@saturn.ucsc.edu> <1280@atari.UUCP> <471@bdt.UUCP>
Reply-To: hafer@infbsgr.UUCP (Udo Hafermann)
Organization: TU Braunschweig,Informatik,West Germany
Lines: 90

In article <471@bdt.UUCP> david@bdt.UUCP (David Beckemeyer) writes:
>
>BEWARE! *NONE* of these networks have been even close to being real.
>
>[...] This is just
>a warning to would-be "believers" - be wary of ST network claims.

This puts me in a difficult position - but nevertheless: 

We have a transputer-based network connecting (at this time) seven STs
to (at this time) two servers up and running for over a year now.  A
short description follows:

Introduction
------------

The Atari network described here has been heavily used in our own
projects for a year.  It provides multi-user access to shared disk space
using the familiar TOS interface. 

The network utilises Inmos transputers with their fast link connections. 
Work is currently being done to integrate IBM-compatible PCs into the
network and to implement an interface to the inter-user communication
facilities. 

Hardware
--------

The network requires at least one server.  A server is an Atari ST (512
Kbytes of RAM are sufficient) with a harddisk (although in principle any
drive, including large RAM disks, could be used).  It has the sole task
of handling requests from the network, thus managing access to its disk
data.  A server Atari cannot be used otherwise while the network is in
operation. 

There may be many servers in the network.  All other network
participants are called users.  A user thus is an Atari with or without
a local (non-server) harddisk, connected to the network via a so-called
Adapter Box which plugs into the ROM port.  An RS424 line connects the
Adapter Box to a transputer.  In this manner, the network can be
extended to almost any size. 

Software
--------

From a user's view, the network provides additional TOS drives, for
which the drive specifiers P downto minimally G are used.  Drive
specifiers are assigned to disks or partitions of servers independently
(and dynamically) for each user.  The icon-driven desktop user interface
is fully operational.  A single file can be opened for reading by any
number of users (if no-one has write access); however, a file can be
opened for writing only if no other user is accessing it. 

The user's computer gains network access by loading a resident program
which redirects TOS requests for network drives.  All TOS calls are
supported; BIOS calls for network drives are not possible (and
protection mechanisms therfore cannot be by- passed).  A few new TOS
calls for internal network purposes have been added.  Network access can
be dynamically de-installed. 

Programs can be loaded and run from network drives (although they are
actually executed on the local computer).  Hierarchical inheritance of
I/O-redirection and current paths are implemented in the usual manner. 

If a user program crashes (bombs etc.), the network remains operational
for other users.  The crashed computer must simply be rebooted.  It may
however be necessary to explicitly close files which were opened on a
server but not closed.  Software support for this is provided. 

Two additional programs allow users to have temporary exclusive access
to the printer connected to the Boot Server.  All printer output via DOS
calls is then redirected to the boot server's printer. 

---------

As said, the network is *operational* (and, incidentally, will be on
display at the CeBiT Hannover Fair this year), and we are quite happy
with it.  Mail me for more details.


	Udo Hafermann
	Abteilung fuer Theoretische Informatik
	Bueltenweg 74/75
	Techn. Univ. Braunschweig
	D-3300 Braunschweig
	W. Germany

email:
	hafer@dbsinf6.bitnet		(preferred)
	hafer@infbs.uucp