The multiuser systems that also networks IBM PCs

Here's an apparently short-lived advert for the Ultraframe multi-user systems from Synamics Business Systems Ltd of London.

Actually built by OEM manufacturer IBS Incorporated of the US, and assembled under licence in the UK by Synamics, the Ultraframe was one of a group of "desktop" multiuser systems which included competition from [@Bromcom], [@Altos], [@Hotel Microsystems]/HM and [@Jarogate].

All of these systems were based on the concept popular at the time where a host computer housed individual processor cards each of which supported a smaller number of users, typically two to four. It was not unlike a blade server, albeit aimed at one-to-one direct local connections rather than cloud usage.

In this case, the Ultraframe could host either 12 or 20 such cards on its S-100 bus - each of which could run either an 8-bit Zilog [!Z80|Z80B] or a 16-bit Intel [!80186] - supporting up to a maximum of 36 users. 

The 36 individual 25-pin serial ports which these users connected to via a terminal can even be seen in the advert above, in the photo marked "back".

It was also possible to network up IBM PCs to the Ultraframe over ARCnet, in a move which in hindsight looked like inviting the wolf to look after the sheep.

Originally developed when hard disks were significantly expensive and so were worth sharing, it was the commoditisation of IBM PCs, thanks largely to the rise of the clones, and the decreasing cost of Ethernet local-area networks that effectively killed off desktop multi-user machines such as this.