Psion Series 3
The Psion Series 3 range of personal digital assistants were made by Psion PLC. The four main variants are the Psion Series 3 (1991), the Psion Series 3a (1993), the Psion Series 3c (1996), and the Psion Series 3mx (1998), all sized 165 by 85 by 22 millimetres (6.50 in × 3.35 in × 0.87 in). Further, a Psion Series 3a variant with factory installed software for the Russian language was called a Psion Series 3aR, and Acorn Computers sold renamed versions of the Psion Series 3 and 3a marketed as the Acorn Pocket Book and Acorn Pocket Book II. The Psion Series 3 range was regarded in 2009 by writer Charles Stross as an unsurpassed PDA because of its long battery life (20 to 35 hours), its stable and versatile software, and its durable hardware.