Level 1
The Level 1 server operated on a BBC microcomputer and offered little more than a networked DFS
emulation.
Level 2
Using a BBC microcomputer with a co-processor, the Level 2 server introduced the concept of
users and passwords.
Level 3
Using a BBC microcomputer with a co-processor, this was the first complete server. It
offered many of the features of the FileStore, but only required a dedicated computer.
FileStore
This was a dedicated machine based around a 6502, and housed in a Master Compact style box. By
Acorn standards, it was quite a compentent server although it suffered from serious
lethargy. This was not so noticable with BBC micros as they tended to transfer small amounts of
data; and so a built in printer server, two 3.5" floppy discs and connection for a harddisc,
it was quite a reasonable device ... provided you disabled the on-board clock!
SJ Research MDFS
The MDFS offered it all, and then some. With two printer ports, capability to add four floppy
discs and a chain of SCSI harddiscs, the hardware facilities were impressive.
The server side, just as impressive. 'Private' directories, good control over what users
could/could not do, accounting, printer servers that could hold or spool printouts, and from the
supervisor side - the ability to print a real-time report of what was going on at a level of
logging you choose.
The MDFS was SJ's crowning achievement. Single Z80, fully multi-tasking (I'm not sure if any of the earlier SJ servers were), serial and parallel printer spooling, heirachical filing system. Came as a main box and a load of connectors, into which you could plug up to four double density floppy drives and SCSI discs and tape drives. Server version 1.10 supported up to 8 partitions of 35MB each - individual SCSI discs could have one or more partitions on them. 2.00 increased the partition size to 59MB. The limit in the disc format is 64MB, but it was kept to 59 to ensure two partitions fitted on a 120MB backup tape.
Level 4
Acorn's wander into serving from a RiscOS machine. It offers pretty much the same facilities as
the FileStore, only it does it about 10 times faster. Level 4 operates as a multitasking
application, but can (if necessary) work in a single-tasking mode.
awServer
Written by Alan Williams between 1989 and 1991, this is quite a reasonable attempt at emulating
a FileStore on a RiscOS machine - and it multitasks!
There are some bugs, but as a free server it is invaluable for a quick'n'easy network. Several
machines, Econet interfaces for each, a few bits of wire and a clockbox. Run awServer on one of
the machines, away you go.
Advanced Level 4
Released at the end of 1997, somebody somewhere still thinks there is commercial viability in
Econet. This is an upgrade on Level 4 which offers many new facilities and makes it a little
more like the MDFS. It does offer a 32bit NetFS (existing versions are 24bit) which speeds up
communications across the network, though making it incompatible with 6502 machines and the
MDFS. A 24/32bit version is planned.
It seems expensive (in my largely-ignored opinion), but luckily you can try before you buy: find
out more at http://www.planet.demon.co.uk/.
SJ Research HDFS (Hard Disc File Server)
This was a monstrous beast needing two people to lift safely - containing one or two 10 to 30MB
ESDI discs and a 60 MB tape drive. The fan sounded like an aircraft taking off. It�was
excruciatingly expensive at the time, but the only competition was Acorn Level 2 so people
bought it anyway. The PCB was huge and was a twin Z80 design. Started as a flat filing system
but became heirachical and gained a printer spooler process during it's lifetime. Very few of
these (if any) are still in use.
SJ Research FDFS (Floppy Disc File Server)
The FDFS was a fairly successful attempt to reduce the price point of SJ networking. It had
enough ports to connect 4 double sided Quad Density floppies, though most people used Double
Density. It had a heirachical filing system and a printer spooler and used a single Z80.
Few/none still in use since no option for adding a hard disc.
Nucleus
Nucleus (also known as Level 5 for a while) is the fileserver that sank two companies - Digital
Services and Cumana. It was an all singing all dancing server on a Risc PC using a DMA SCSI card
and a custom filesystem (to get around the 512Mb disc limit). It was basically meant to be as
sophisticated as an MDFS, but it foundered on the rocks of taking too long to write without
making any money. Some schools had beta test copies that they speak quite highly of. The
original 32 bit NetFS work (old versions of NetFS have a 24 bit filesize limit) was done for
Nucleus.
And...
It appears that other people have written their own servers. I, myself, have begun coding
"LevelFive" (which can just about serve a file - if you ask it REALLY nicely).
Other servers (one also apparently called Level5!) seem little more than rumours, but I'm sure
they exist.
If you have a server you would like me to mention here, please send me a copy so I can see it in action. If your server has a sufficient number of users, I shall include it in the main menu under "Servers". Email me!