On Oct 5, 18:20, Tony Duell wrote:
> Does anyone have any experience with Acorn Econet (Acorn's low-cost,
> fairly low-speed network)?
I used to install Econet systems, and upgrade and repair Beebs with
Econet. I must have installed or re-installed a few hundred Econet
interfaces. A certain large dealer once tried to save money by farming
out BBC Model Bs for Econet upgrade jobs to his local ITeC (a sort of
training centre of out-of-work youngsters). An upgrade includes lots
of 10K, 100K, and 1M resistors, a handful of capacitors, and a bunch of
ICs, and on early BBCs most of the passive components get fitted
vertically in very tight spaces; not surprisingly, the majority of
those upgrades didn't work. I got to be very good at faultfinding on
those things before the dealer finally conceded that it would be
considerably cheaper to just get me to fit the upgrades in the first
place :-)
> Digging in my junk box (well, more like junk room :-)), I've found a
> couple of Econet clock boxes (one Acorn, one SJ, these supply the
data
> clock for the network), a terminator, various connector boxes, etc.
> Cabling shouldn't be a real problem either, I assume the right cable
is 2
> twisted pairs with an overall screen.
Ideally, twisted quad stranded with an overall screen and stranded
drain wire, but Cat 3 or better is fine so long as you have the fifth
(ground) wire and a half-decent screen. The original Econet in Acorn's
Market Hill office in Cambridge ran on telephone cable. You do need
the ground connection, though -- two pairs isn't enough on their own.
> I believe I need a fileserver (== a machine set up as such). Assume I
> have Beebs (with Econet interfaces), 6502 and Z80 second processors,
A310
> (but no backplane, therefore no expansion), A3000 (no expansion
either),
> A3010 (in bits, but probably repairable), a couple of Systems (one
with
> an Exonet interface), and not a lot else. I think I could find the
Acorn
> SASI/SCSI host interface for the Beeb if pushed, and I have a Beeb
with
> the Torch SCSI card and SCSIFS. Oh, and an Acorn Econet bridge, but
> that's fairly useless at the moment...
There are six Acorn file servers, and some from SJ Research. I don't
know much about the SJ ones (except that early ones had some
compatibility problems) but the Acorn ones (in date order) are:
The original Econet Fileserver -- runs on a System 5, uses 2 x 80-track
DS SD floppies, formatted in a unique way. I've not got the software
for that, and I've never used it.
Level 1 Fileserver -- provides LOAD, SAVE, etc for files, and some
utilities such as sending messages, viewing screens, etc, but not much
more in the way of file services. Runs on an ordinary Model B with
disk^Wdisc interface and normally uses two double-sided 80-track drives
(but will work with any drive that supports DFS). Limited to whatever
the standard DFS floppies hold (ie subject to the normal DFS file
limits).
Level 2 Filserver -- runs on a Beeb with a 6502 Second Processor, uses
one or two DSSD 80-track drives, same disc format as the System 5
server. Not subject to the DFS number-of-files limits, supports
random-access files, etc.
Level 3 Fileserver -- runs on a Beeb with Beeb with a 6502 Second
Processor, ADFS, and a 10MB or 30MB winchester. The winchester is
partitioned, and the Econet Fileserver partitiion has a unique
filestructure. Needs a dongle, which is also a TOD clock. Most
dongles are now dead (and weren't Y2K compliant) but there's a patch to
bypas that. It also came with a modified version of CommunITeL
viewdata bulleting board software.
Stacking Filestore -- a box that looks like the disc unit from a Master
Compact (or a Communicator), with a brown smoked Perspex front flap
covering twin 3.5" floppies, basically a revamped Level 3 but able to
use floppies or a winchester. The flap is also a control switch; open
it to shut down the server, close it to restart. It also includes
printer server software. The matching winchester is just a small SCSI
drive (yes, real SCSI, not SASI) in a matching box, normally a 3.5"
20MB Rodime drive; you can have up to six IIRC.
Level 4 Fileserver -- software application that runs on an Archimedes
under RISC OS 2 or later. It really wants an A440 or better, but
should just about run on an A310. Uses whatever filing systems/media
are available to RISC OS, and can act as an Econet/Ethernet bridge.
> Any ideas as to what I should use, and where to get the necessary
> software. Has anyone ever hacked a PC to work as an Econet
fileserver?
> The hardware wouldn't be too bad, I think.
Level 1, 2 and 3 fileserver software isn't hard to come by if you know
someone who has it (hint: you do :-)) The discs are copyable. Level 3
is only useful if you have a suitable winchester amd copro on a Beeb,
and you'll need the installer discs (I forget whether it's one or two)
*and* the anti-dongle patch (unless you want to reverse engineer one of
my resin-encapsulated dongles -- but be warned, I've been told by Those
Who Know Such Things that the necessary chips haven't been available
for many years).
You might be able to download Level 4 from the net somewhere. I think
I have a copy -- but not a very good one. It went through a few
iterations!
> Has anyone ever hacked a PC to work as an Econet fileserver?
> The hardware wouldn't be too bad, I think.
Nope. The Ecolink ISA card only works under MS-DOS 3.21 (or some
similar version) and an 8086 machine hasn't the oomph to make much of
an Econet system. It even needs a (6502 -- what else?) processor on
the Ecolink card to handle basic network operations. Ecolink cards are
genuinely rare -- I have one, Jules R has one, and I know of only a
couple of others.
> Anything else I should be aware of?
By convention, an Econet address is two octets, the upper octet is
network number ("0" means "the local net"), the lower is the station
number. On Beebs, Atoms, Systems, you set the station number with
molex links; on later machines you set it in the CMOS. On Master
Series machines, you need a special utility because it's in a protected
memory area. Address 255 is the broadcast address; 0 is invalid (sound
familiar?). By convention, the fileserver is station 254, and the
printer server is 235. In some versions of the NFS or ANFS software,
stations above 128 (? memory check) are privileged and can force
certain operations on unpriv'd stations. Normal stations can *PROTECT
themselves from various ops except from priv'd stations (operations
include read/write memory blocks, jump to an execution address, force a
file load/save etc -- remember this was designed for classroom use).
There are Econet interfaces for Systems, Atoms, Beebs (A, B, B+),
Master Series (including Compact), ABCs/Scientifics (built in as you've
discovered), Electrons (from HCCS, not Acorn, though), and all of the
Archimedes/RISC PC range. The A/B/B+ interfaces are a bag of
components. The System one is a Eurocard, the Atom one is a plug-on
module (as is the Electron one). The later Master Series and RISC
machines ones are a small module. There are two versions of the
module: originally Acorn designed it with full collision-detect
circuitry, then someone decided it would work fine without, at least on
an Arc where the faster processor could do some extra work. Sadly,
that wasn't borne out in real life, so after a while they reverted to
the original design with CD.
Issue 2 and 3 Beebs have a lot of the components mounted vertically to
save space; they also have provision for clock and/or terminators on
the BBC board. This is not a good idea; the original terminator design
was an active device, and doesn't work if there's no power (and neither
does the clock, obviously!). Issue 2/3 also need a few track
cut/rewires. Issue 4/7 have the components laid out horizontally (more
sensible) and no provision for clock or terminator on board.
The speed of the net depends on the length, the longer the slower. Max
speed is obtained with a short network and an asymmetric mark-space
ratio on the clock. Early Acorn clock boxes use a square wave; later
ones, and SJ ones, have variable mark/space. Early terminator boxes
(small light+dark grey Veroboxes) match the clock boxes and provide
active termination. Later terminators, and SJ terminators, are
passive: DIN plugs with a few resistors, and inferior. Arcs and later
RISC-based machines can, not surprisingly, handle faster networks (up
to about 500kHz clock) than Atoms/Systems/Beebs (250kHz clock).
Torchnet runs on the same hardware as Econet, but uses its own
nearly-compatible protocols.
The Acorn Printer Server is a 2732 sideways ROM; it doesn't do queueing
or anything fancy (ie it can only handle one job at a time) but works
with most printers, from dot-matrix to laserjet. The XOB advanced
version handles queueing, as does a later one from Acorn for RISC OS.
If the server isn't too busy, FS and PS can be on the same machine.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Mon Oct 06 2003 - 15:40:03 BST