drive (hard disk) for the E01 base unit; later expansions in the form of the E40S and E60S provided 40 MB and 60 MB storage respectively for the E01S base unit. The "S" suffix reportedly signifies that the units are "stacking". Fileserver Acorn also offered the Level 1, Level 2 and Level 3 Fileserver solutions running on sufficiently upgraded BBC Micro or BBC Master computers. The Level 1 product offered access to existing Acorn DFS discs via a BBC Model B with Econet, a disc interface and single or dual drives. Printer sharing was also possible. This was intended for small networks, typically in an educational setting, to solve a narrowly defined problem of sharing what were at the time expensive peripherals. An Econet upgrade originally cost significantly less than a disk drive. The only available access control mechanism was that files for each station (client) on the network could be isolated from each other but anyone with physical access to the relevant station could access the files. Typically each station would only be able to access a small number of files, with only 31 files being stored in total on a side of one floppy disk and split between all of the stations. Level 2 delivered significant enhancements over level 1 but elevated the system requirements for the file server host machine to necessitate a 6502 second processor unit with 64K RAM. Hierarchical directories were possible with the number of files limited only by the amount of storage available, enhanced access controls, random access to data files, and authentication support. Level 3 introduced Winchester hard drive support. With the release of the Level 4 Fileserver software providing a means to "extend the life of existing Acorn computers, such as the A310", allowing "any Archimedes computer to act as a fileserver", the emphasis had evidently shifted away from the Filestore and towards the Level 4 product at the start of the 1990s. A base Filestore E01S unit had a price inclusive of VAT of £1148.85 in February 1989, whereas an Archimedes 310 with 1 MB of RAM cost only £958.00 and an Econet module £56.35, illustrating the pricing considerations for potential buyers. By 1991, the Filestore was apparently no longer offered in Acorn's pricing (nor was the A310), but the Level 4 software was priced at £233.83 and an Archimedes 410/1 with 1 MB of RAM at £1049.33. Unix system