Not another new company with a personal computer

Branding itself as a "new" company, ITT had actually been around for a while. It was already famous for its ITT 2020 microcomputer of 1979 - the first official clone of the Apple II for the European market.

However, after its initial stash of Apple-supplied motherboards ran out, it was stiffed by Apple when the latter decided to build its own European computers in Ireland, cutting ITT out of both the Apple II market and its follow up, the Apple III.

ITT followed up with the ITT 3030 - a completely-unrelated bog-standard but expensive Z80A system which could run CP/M, MP/M, BOS 5 or the UCSD p System.

By the time of this advert it's the era of the IBM PC, and so ITT's machine is - unsurprisingly - an IBM compatible. However, unlike quite a few clones of the time, it's fully compatible with IBM's latest model, the XT. 

This meant it could actually run Lotus 1-2-3[source: https://www.atarimagazines.com/creative/v10n12/71_ITT_Xtra_an_IBM_PC_compa.php] the spreadsheet-cum-database application suite which was at the time something of an "acid test" - along with Microsoft's Flight Simulator - for software compatibility.

The Xtra was built for ITT by STC - originally Standard Telephones and Cables Ltd, and which had founded in 1883 as a London outpost of Western Electric. This company was sold to ITT in the mid 1920s, but became independent in 1982, before disappearing into Nortel in the early 1990s. 

Using the STC branding prominently probably helped give the machine some "made in Britain" credibility.
