EPOC (operating system)

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Osaris PDA by Oregon Scientific with EPOC operating system

EPOC is a discontinued family of graphical operating systems developed by Psion for portable devices, primarily PDAs. EPOC came from epoch, the beginning of an era, but was backfitted by the engineers to "Electronic Piece Of Cheese".[1] It was succeeded by Symbian in 1998.


EPOC16, originally simply named EPOC, was the operating system developed by Psion in the late 1980s and early 1990s for Psion's "SIBO" (SIxteen Bit Organisers) devices. All EPOC16 devices featured an 8086-family processor and a 16-bit architecture. EPOC16 was a single-user preemptive multitasking operating system, written in Intel 8086 assembler language and C and designed to be delivered in ROM. It supported a simple programming language called Open Programming Language (OPL) and an integrated development environment (IDE) called OVAL. SIBO devices included the: MC200, MC400, Series 3 (1991–98), Series 3a, Series 3c, Series 3mx, Siena, Workabout and Workabout mx. The MC400 and MC200, the first EPOC16 devices, shipped in 1989.

In the late 1990s, the operating system was referred to as EPOC16 to distinguish it from Psion's then-new EPOC32 OS.

EPOC32 (releases 1 to 5)[edit]

The first version of EPOC32, Release 1 appeared on the Psion Series 5 ROM v1.0 in 1997. Later, ROM v1.1 featured Release 3 (Release 2 was never publicly available.) These were followed by the Psion Series 5mx, Revo / Revo plus, Psion Series 7 / netBook and netPad (which all featured Release 5).

The EPOC32 operating system, at the time simply referred to as EPOC, was later renamed Symbian OS. Adding to the confusion with names, before the change to Symbian, EPOC16 was often referred to as SIBO to distinguish it from the "new" EPOC. Despite the similarity of the names, EPOC32 and EPOC16 were completely different operating systems, EPOC32 being written in C++ from a new codebase with development beginning during the mid-1990s.

EPOC32 was a pre-emptive multitasking, single user operating system with memory protection, which encourages the application developer to separate their program into an engine and an interface. The Psion line of PDAs come with a graphical user interface called EIKON which is specifically tailored for handheld machines with a keyboard (thus looking perhaps more similar to desktop GUIs than palmtop GUIs [2]). However, one of EPOC's characteristics is the ease with which new GUIs can be developed based on a core set of GUI classes, a feature which has been widely explored from Ericsson R380 and onwards.

EPOC32 was originally developed for the ARM family of processors, including the ARM7, ARM9, StrongARM and Intel's XScale, but can be compiled towards target devices using several other processor types.

During the development of EPOC32, Psion planned to license EPOC to third-party device manufacturers, and spin off its software division as Psion Software. One of the first licensees was the short-lived Geofox, which halted production with less than 1,000 units sold. Ericsson marketed a rebranded Psion Series 5mx called the MC218, and later created the EPOC Release 5.1 based smartphone, the R380. Oregon Scientific also released a budget EPOC device, the Osaris (notable as the only EPOC device to ship with Release 4).

Work started on the 32-bit version in late 1994.

The Series 5 device, released in June 1997, used the first iterations of the EPOC32 OS, codenamed "Protea", and the "Eikon" graphical user interface.

The Oregon Scientific Osaris was the only PDA to use the ER4.

The Psion Series 5mx, Psion Series 7, Psion Revo, Diamond Mako, Psion netBook and Ericsson MC218 were released in 1999 using ER5. A phone project was announced at CeBIT, the Phillips Illium/Accent, but did not achieve a commercial release. This release has been retrospectively dubbed Symbian OS 5.

The first phone using ER5u, the Ericsson R380 was released in November 2000. It was not an 'open' phone – software could not be installed. Notably, a number of never-released Psion prototypes for next generation PDAs, including a Bluetooth Revo successor codenamed "Conan" were using ER5u. The 'u' in the name refers to the fact that it supported Unicode.

In June 1998, Psion Software became Symbian Ltd., a major joint venture between Psion and phone manufacturers Ericsson, Motorola, and Nokia. As of Release 6, EPOC became known simply as Symbian OS.


  1. ^ Hood, Ann (2000-05-15). "Wireless warrior - Salon.com". Archive.salon.com. Retrieved 2010-08-12. 
  2. ^ Marcin Wichary. "GUIdebook - Screenshots - EPOC R5/Psion Revo". Guidebookgallery.org. Retrieved 2010-08-12.