I know very little about this machine or the company behind it. Scant info is available on the web so hopefully some mailing lists will come up trumps

Cambridge Systems Technology (a "backronym" apparently) was started by David Oliver and Martin Baines after they (and lots of others) left Torch in Cambridge, with Graham Priestley arriving later. They knew the Sinclair QL was a good machine at heart so they used it as a basis for their first range of machines.

• The single 720k floppy drive Thor 1F
• The dual 720k floppy drive Thor 2F
• The 20mb SCSI HD Thor 2WF

All these machines were designed round the QL motherboard, so unnecessary items like the keyboard and microdrives were discarded and a new board designed that connected to the QL's expansion port. This new board contained extra memory to take the base up to 640K, a ROM extender board and a WD disk controller to give the machine floppy and hard drive capability.

Also on the new board were an RS232 port, an AT-style (but not compatible) keyboard port, centronics port and the QL expansion port replicated out the back of the machine. Access to all the other QL ports was provided too with holes on the back of the smart and rather heavy new metal case everything lived in.

The system ran a modified QL operating system and included the TSL task sequencing language similar to the ICL OPD/Merlin Tonto so you could run up to 6 instances of the bundled Psion Xchange application suite (again as on the OPD/Merlin) and share data between them. Pretty good for its day! Pity my machine doesn't have its HDD any more so I might not get a chance to find out what the new front-end looked like :-/ I've found public domain versions of Xchange on the web however, so at least I can get that running once I get a hard drive.

Based on the info found at the same Xchange site the production of Thors stopped in 1989 because of cashflow problems.

A couple of years ago the Thor was one of my battery panic moments, you can see a VARTA MEMPAK in the 2004 pics which over the intervening years has quietly deposited its contents over that side of the board. Fortunately in 2016 the damage cleared up OK but I didn't power up at the time. Fast forward to 2018 and all looks good. Must buy/make a SCART cable for this and my QLs.