REX OS
In today's world, REX OS has become a topic of increasing interest to a wide variety of people. Over time, REX OS has proven to be relevant in different contexts and situations, which has generated a great debate about its importance and its impact on society. Since its emergence, REX OS has sparked the interest of experts and hobbyists alike, who have dedicated time and effort to better understand it. In this article, we will explore different aspects of REX OS and analyze its influence in different areas, in order to provide a comprehensive view on this very relevant topic.
 | This article needs to be updated. (May 2023) |
| REX Operating System | |
|---|---|
| Developer | Qualcomm |
| Written in | C[1] |
| OS family | L4A Pistachio and Iguana embedded operating system |
| Working state | Discontinued |
| Source model | Proprietary |
| Initial release | 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.
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:
- Preemptive multitasking
- Task management
- Task synchronization
- Exclusive lock
- Timer
- Interrupt management
- Uses less than 5K of ROM[1]
REX provides no memory protection features but does have memory management abilities.
References
- ^ a b c "REX and Common Software". Retrieved 2025-11-11.
- ^ Edgewall Software. "HTC Vision". Retrieved 2012-03-12.
- ^ Asif, Saad Zaman (2011-01-11). Next Generation Mobile Communications Ecosystem: Technology Management for Mobile Communications. John Wiley and Sons. p. 299.
External links
- Iguana Archived 2006-04-26 at the Wayback Machine
- L4 Based Operating Systems Archived 2018-06-14 at the Wayback Machine
- NICTA L4-embedded Kernel Archived 2014-02-27 at the Wayback Machine
- Qualcomm Corporate Site
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