Psion Series 5mx
The Psion Series 5 was easily my favorite ever PDA. Not sure it really belongs in the annuls of rugged portable history, as it was certainly a consumer-grade device, and the ever-so clever sliding keyboard mechanism did tend to flex the flexi-cable a bit too much… If you have one and need to know how to repair it – this link – is to a wonderfully detailed disassembly and repair guide. I had a Series 5mx, and I’m not going to do two posts – the mx was faster – 36MHz rather than 18Mhz. The display was not all that wonderful, a half-VGA 640 x 200 LCD with 16 shades of grey.
MUST READ: This is a great read – the history of the PSION Series 5 by Andrew Orlowski of the Register
I remember going through many many sets of AA batteries as they seemed to only last two or three days of heavy use.
The operating system was called EPOC (which became Symbian later bought by Nokia and shuttered in 2012) and included a word processor, spreadsheet, email client, database, contact database and diary.
Psion these days actually is a designer of rugged portables – and is part of Motorola Solutions. Not sure if they were sold to Lenovo or not.
Design
The design of the series 5 (and hence 5mx) was done by Martin Riddiford who worked for Therefore Design in London. It featured a sliding keyboard, which was actually usable, and a touch screen. Psion was awarded a patent for the device not tipping over when you used the touch screen. Such innovation! I liked the stylus so much I bought ten of them and donated them to the production department at Dolch Computer Systems in Fremont, CA for the calibration of touch screens.

Psion Series 5 Side View (from Old Organizers.com)
Construction
Unusually even then the PSION Series 5 was manufactured in the UK.
I know I have still got my Series 5 somewhere in the garage – and I’ll replace these images with ones of my own if I ever find it!
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