EKA1

EKA1 (EPOC Kernel Architecture 1) is the first-generation kernel for Symbian OS. It offers pre-emptive multitasking and memory protection, but no real-time guarantees and a single-threaded device driver model. It has now largely been superseded by EKA2.
Much of EKA1 was developed by a single software engineer, Colly Myers, when he was working for Psion Software in the early 1990s. Myers went on to act as CEO for Symbian Ltd. when it was formed to license this kernel and associated operating system to mobile phone manufacturers. He is now CEO of Issuebits Ltd.
See also: Psion.