The Psion Series 5 was a PDA (Personal Digital Assistant) from Psion. It came in two main variants, the Series 5 (launched in 1997) and the Series 5mx (1999). The Series 5mx had a faster processor, clearer screen, and updated software. There was also a rare Series 5mx Pro, which differed only in having the operating system loaded into RAM and was therefore upgradeable. Ericsson marketed a rebadged version of the Series 5mx called the MC218.

The 5mx had a 32-bit RISC-based ARM710T RISC CPU, running at 36 MHz and 16MB of RAM as standard. The Series 5 PDAs ran EPOC32 operating system. The EPOC32 OS was the precursor to the Symbian OS, which was one of the dominant early smartphone operating systems until 2011. The Series 5mx had a greyscale LCD screen, which was touch-sensitive, and came with a stylus that slotted into the unit when not in use. The unit was powered by two AA batteries and a CR2032 back-up battery, which was said to provide a one month typical life. There was also a optional external power supply. 

Further Technical Details:

• Expansion: One CompactFlash slot for up to 20 MB storage on Psion Memory Disk (CompactFlash standard)

• Display: 16-level grayscale, 640 x 240 pixels, view full page width; backlit, touch-sensitive screen; 100 characters by 26 lines with rich text and multiple zoom levels; 5.25-by-2-inch active viewing area

• Keyboard: Patented touch-type laptop-style "expanding" keyboard with a large vertical travel, 9 offscreen quick-access application icons, 5 command icons

• Audio: Microphone for digital sound recording; external buttons for record, stop, play, and rewind and for silencing alarms; internal speaker

• Access to thousands of names, addresses, phone numbers, and appointments

• Built-in e-mail

• Communications: RS232 fast serial port interface to computers, modems, mobile phones, and printers at up to 115 Kbps; IrDA-compliant infrared port (range up to 1 meter) for printing and transfer of information from a Psion to a suitable printer or another Psion Series 5 palmtop

• Size: 6.7 x 3.5 x 0.9 inches

• Weight: 12.5 ounces with batteries

Magazine Articles About Series 5

• Personal Computer World - September 1997
• Acorn User - December 1999