Yeah, where do I start?  Tandata Design Consultants was running as a modem 
designer back before '84, when I first was introduced by a colleague at uni 
who had worked there for a while. I remember someone saying that all the 
honest people from Tangerine went to Tandata, and everyone else formed Oric!

By '84, a project had just been conceived called "Minerva". It was a 
desktop comms station, with a hands-free phone, nice keyboard, modem, 
TV/Monitor, a little LCD panel, and tons of battery-backed RAM. It had a 
word processor, address book, spreadsheet, etc ... precursor of a PDA, 
really.  It was a very ambitious project, but with enough comms emphasis 
that the company had the expertise to build it.

I worked there for the three summer vacations during my degree. Over that 
time, more and more people got sucked into Minerva, until, by '86, I and 
one colleague were about the only people *not* working on it!

By that time, the machines were all built, and they worked, and they were 
being sold, and it was wonderful ... except that there was a bug. After a 
week, or a month, but sometime, your Tandata PA (as the product was called) 
would crash and require a cold boot, losing all your addresses and docs 
which were held in the battery-backed RAM.  And there was no backup 
facility, so you tended to lose everything -  a fact that meant that there 
was *absolutely* no room for bugs.

It took months and months for the problem to be solved, because it was so 
intermittent - long after I'd left, it turned out there was something 
special about the ROM's ZIF sockets, and they would fail over time 
(corrosion maybe? can't remember).  Of course, I imagine that there were 
lots of other "candidate" bugs that were swept up in the process. But as a 
result, the product started well, but never really sold once this problem 
became an issue. The ICL "One-per-desk" came out, too, and did more or less 
the same stuff, but it had a (ZX-style) microdrive built in, so it didn't 
need to be as robust.

The PA never recouped its development costs, and by about '87/'88 it killed 
the company, which ended up being bought out by the firm that fabricated 
its products (AB Electronics, in Wales).  The commercial office (Tandata 
Marketing Ltd), in Malvern, kept going for a while, I think.