| REX Operating System | |
| Developer: | Qualcomm |
| Source Model: | Proprietary |
| Kernel Type: | Microkernel RTOS |
| Supported Platforms: | ARM |
| Family: | L4A Pistachio and Iguana embedded operating system |
| Released: | [1] |
| Discontinued: | Yes |
| Working State: | Discontinued |
| License: | Proprietary |
| Marketing Target: | Smartphones |
| Programmed In: | C |
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.
REX is an RTOS with the following features:
REX provides no memory protection features but does have memory management abilities.