REX OS

Last updated
REX Operating System
Developer Qualcomm
Written in C [1]
OS family L4A Pistachio and Iguana embedded operating system
Working stateDiscontinued
Source model Proprietary
Initial release1999;26 years ago (1999) [1]
Marketing target Smartphones
Supported platforms ARM
Kernel type Microkernel RTOS
License Proprietary

The REX Operating System (Real-time Executive Operating System) is a real-time operating system (RTOS) developed by Qualcomm for the ARM processor based mobile phone Dual-Mode Subscriber Station (DMSS) or Advanced Mode Subscriber Software (AMSS) development. As of 2007, most Korean cell phones ran on REX.

Contents

REX is a combination of two operating systems: L4Ka::Pistachio embedded microkernel and Iguana , with extensive modifications and extensions by Qualcomm and HTC. [2]

Originally developed for the Intel 80186, it was then ported to ARM, and x86 architectures are no longer supported. REX is not POSIX compliant or open-source software and requires a proprietary software license from Qualcomm for use. [3]

It seems not to be actively developed or marketed as of 2012, but is used in currently or recently sold low end cell phones, typically for use by pay-as-you-go customers, like the Samsung SPH-M300.

Features

REX is an RTOS with the following features:

REX provides no memory protection features but does have memory management abilities.

References

  1. 1 2 3 "REX and Common Software" . Retrieved 2025-11-11.
  2. ↑ Edgewall Software. "HTC Vision" . Retrieved 2012-03-12.
  3. ↑ Asif, Saad Zaman (2011-01-11). Next Generation Mobile Communications Ecosystem: Technology Management for Mobile Communications. John Wiley and Sons. p. 299.
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