Creating a new EPOC

In 1994, realizing the limitations of SIBO, Psion started a new project named Protea that was to build a new 32-bit operating system and application set for delivery on a new hardware platform.

At the outset the project was given clear goals: the new system would be better than the Series 3 with GUI interaction, better communications and PC synchronisation, but it was not going to go beyond that. The reason for this was that Psion recognised the "second-system effect" which for other companies had resulted in significant project overruns, as there was always another fault to fix or enhancement to add.

Martin Tasker gives a detailed insight into the project in the book Professional Symbian Programming from Wrox Press. The following highlights are however worthy of note:

• The code development platform was chosen as Microsoft Visual C++ (because of its powerful debugging capabilities) running on Windows NT.
• The project set out to fully harness the power of C++ using the Object Orientated paradigm. The unsuccessful joint IBM / Apple project Taligent was used as an invaluable information source in this regard, coupled with Psion's own experience in SIBO.
• The user interface initially was to follow Windows conventions, e.g. the use of tab to move between fields and Alt for accelerators to fields. After some debate it was decided to revert to Series 3 style where cursor arrows (up/down) moved between fields and tab activated an extended list for a field. This was done as the Windows standards were felt not to be intuitive to non-PC users. (Despite the apparent confusion that this would seem likely to cause for a user of both systems the transition is actually quite straightforward.)
• Hardware was switched from Intel x86 to ARM for its low power usage and MIPs per $ performance.
• Series 3 machines had used static RAM but the switch was made to dynamic RAM, which, while cheaper, put a constant drain on power therefore increasing the pressure on the power management facilities.
• The cam shell design of the Series 5 was chosen because a Series 3 style case or simple folding case would fall over when a pointer was used on the touch sensitive screen.

In 1997, for a cost of a little over £6 million, Psion completed the project and launched the Series 5.