Epson HX-20

Hi, I picked up a couple of Epson PX-4 handheld/laptop computers a few weeks ago. Have not got around to testing them yet. Any identifying text which used to be on the rear labels is no longer there. There is space for a plug-in device/cartridge on the righthand side above the keyboard. Both computers have what appears to be a 1 megabyte static RAM cartridge (possibly battery-backed) in this space. These must have been quite expensive when new. I opened up one of the cartridges. Text on one of the PCBs inside mentioned (from memory) POCKET COMPUTERS LTD 1993, so these are quite recent. In the EPROM sockets underneath the computer is some kind of auditing program; the label read Pocket Computers Ltd AUDITOR V5.2 The labels also mention CP/M 2.2. A web search for "Pocket Computers" Auditor didn't turn up anything. Does anyone have any information on this company? -- Mark