“Tomorrow’s mobile library” went on sale in Japan in July 1990 and was an immediate hit with the gadget-hungry Japanese.

Sony’s Data Discman was a portable CD player with an LCD screen and small Qwerty keyboard. It played 8cm Electronic Books with 200 Megabyte capacity. There was a choice of 35 reference text books and foreign language dictionaries.

DD hit the USA and mainland Europe the next year, with 85 titles including such un-missables as an information disc on US Presidents. By 1992, 100,000 players had been sold, but only 200,000 discs.

Discman ROMs discs were incompatible with conventional PC ROM drives. Compatibility with Philips’ CD-interactive players was promised but never happened. The DD discs stored only raw data and the player had search software built into its on-board electronics. To prevent users from downloading this raw data, the player had no socket for connection to a PC.

The UK got the chance to buy DD players in April 1992 for £350, with a Dictionary of the Living World priced at £60 and Harrap’s Multilingual Dictionary costing £40. The small monochrome LCD screen was so hard on the eyes that Sony always demonstrated it connected to a TV monitor.

“I tried reading the works of Mark Twain,” said one American user, “but very soon gave up.” Sony countered that DD was ideal for finding out how many times Sherlock Holmes said “elementary” or how to say “gasket” in German if you break down on the Autobahn. A deal with BT to put telephone directories on DD discs fell through.

Divided by incompatibility, and trounced by PC ROMs, DD flopped. But in 1997 a batch of brand new, boxed, Data Discmen appeared in the window of a Tottenham Court Road shop. They were labelled as if the format were new and the latest thing in portable computing.