The Leader In Real Time Operating Systems
Green Hills INTEGRITY real time operating system technology—the only technology to achieve both DO-178B, Level A and EAL 6+ High Robustness certifications—has set a new standard for RTOS reliability and security. As a result, hundreds of satisfied customers have adopted the INTEGRITY technology for avionics, radar, networking, telecom, weapons systems, medical systems, not to mention more than twenty military aircraft including the Rockwell Collins RQ-7B Shadow and Northrop Grumman USMC H-1 helicopters.
What is a Real Time Operating System?
A real-time operating system, or RTOS, is a type of operating system that is specialized for use in electronic control systems. An operating system is the software at the heart of a computer system upon which all the other software depends. The operating system controls the allocation of all of a computer system's resources, such as processor cycles, memory, communications, and security. The operating system must satisfy the competing demands for resources required by the many different functions that the computer is supposed to perform. The operating system is the most critical software in any computer system. If the operating system does not work, nothing else will work.
Real-Time Operating Systems Must be "Real-Time"
Microsoft Windows, MacOS, Unix, and Linux are not "real-time." They are often completely unresponsive for seconds at a time. They indicate this condition by displaying an hourglass or a clock symbol or by simply refusing to respond to mouse-clicks or keyboard input. These operating systems can't possibly respond quickly enough to open and close the valves of an eight cylinder automobile engine running at 8000 RPM. Real-time operating systems are operating systems that will always respond to an event in a guaranteed amount of time, not in seconds or milliseconds, but in microseconds or nanoseconds. If a real-time operating system does not respond in real-time, the engine will knock, the bar code scanner will identify a jar of pickles as a can of soup, and the fighter jet won't respond to its controls during a dogfight. This makes traditional operating systems unsuitable for use in electronic control systems.
Real-Time Operating Systems Must be Highly Reliable
Microsoft Windows, MacOS, Unix, and Linux often crash, lock up, or go crazy. They indicate this condition by displaying a sad face, an exploding bomb, a red X, a blue screen of death, or by simply refusing to respond to mouse-clicks or keyboard input. If a real-time operating system crashes, locks up, or goes crazy, the car's engine will stop in the middle of the freeway, the supermarket bar code scanner won't scan any more groceries, or the airplane will spin out of control. It is simply not acceptable for a real-time operating system to crash, lock up, or go crazy, ever. This makes traditional operating systems simply unsuitable to control electronic products.
Real-Time Operating Systems Must Work with Minimal Resources
Microsoft Windows, MacOS, Unix, and Linux require millions of bytes of memory and expensive high-speed microprocessors to perform even the simplest tasks. Real-time operating systems for high volume products must use a minimal amount of memory and must operate with the low cost microprocessors typically used in such systems. The expensive microprocessor and memory required by a traditional operating system would increase the production cost of a low cost electronic product, such as a supermarket bar code scanner or an ink jet printer, to an unprofitable level. Even in expensive high volume applications such as automobiles the extra cost imposed by a traditional operating system is prohibitive. This makes traditional operating systems unsuitable for use in high volume products.
Real-Time Operating Systems Must be Designed not Retrofitted
Microsoft Windows, MacOS, Unix, and Linux were designed for computers that had millions of bytes of memory and a high-speed processor. They also assumed that there would be a human operator who would tolerate waiting for a second or two when the operating system was busy and who would reboot the system every day or so when it crashed. These assumptions were built into millions of lines of source code by thousands of programmers over decades. They can't be wished away. The only way to build a high reliability real-time operating system is to plan it from the start. Real-time performance and reliability can't be retrofitted into a traditional operating system. Every attempt to do so has failed. There is no magic wand that can transform millions of lines of big, slow, buggy software into small, nimble, reliable software. This makes traditional operating systems unsuitable for use in high volume products.
Green Hills Real-Time Operating Systems
Green Hills Software's real-time operating systems were designed from the start to meet all of the memory size, performance, and reliability requirements of low priced, high performance, and safety critical electronic products ranging from ink jet printers to supersonic fighter jets.