The Amstore from Northern Computers Ltd. (UK) is a 20MB hard disk for "all existing Amstrad computers" connected by a network.
Amstore was connected through a Multilink network, a token-passing multi-user ring network. The network could be used with any Amstrad machine and with IBM PC, Apricot, BBC and Apple computers. The networking software was Simplenet by Nine Tiles Ltd.
The Amstore Harddisk (and the Amstrad computers) are connected as a 'stations' to this network. There can be max 120 stations, max 3km apart.
Short review on File:ACU8512-078.jpg.
At the Centre for Computing History: