Versatile Real-Time Executive

Versatile Real-Time Executive (VRTX) is a real-time operating system developed and marketed by the company Mentor Graphics. VRTX is suitable for both traditional board-based embedded systems and SoC architectures. It has been superseded by the Nucleus RTOS.
History.
The VRTX operating system began as a product of Hunter & Ready, a company founded by James Ready and Colin Hunter in 1980 which later became Ready Systems. This firm later merged with Microtec Research in 1993 and went public in 1994. This firm was then acquired by Mentor Graphics in 1995 and VRTX became a Mentor product.
Since the 1980s, the chief rival to VRTX has been VxWorks, a Wind River Systems product. VxWorks had its beginnings in the mid 1980s as compiler and assembly language tools to supplement VRTX (i.e. VRTX works, or VxWorks) and later Wind River created their own offering of a real-time kernel similar to VRTX.
VRTX.
VRTX comes in several flavors: 
Most companies developing software with VRTX use ARM, MIPS, PowerPC, or other RISC microprocessors.
Implementations.
VRTX runs the Hubble Space Telescope.
VRTX runs the Wide Area Augmentation System.
VRTX was the first operating system ported to the AMD Am29000.
VRTX is used as a core for the Motorola proprietary P2K () operating system, which runs on most company devices since the Motorola V60 and T280i, up to the Motorola RAZR2 V9x. It runs on several hardware platforms including LTE (Motorola V300, V500, V600, E398, RAZR V3 and others featuring the ARM7 processor), LTE2 (Motorola L7 and upcoming devices with 176x220 screen resolution), Rainbow POG (3G phones featuring an MCORE processor from Motorola E1000 to RAZR V3x), Argon (all new 3G phones with 532 MHz ARM11 processor since Motorola RAZR MAXX V6 and V3xx) and others.