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Overview
of benefits The UNIX operating system, from which MODCOMP derived the REAL/IX PX operating system, is a powerful time-sharing operating system with many high-level utility programs. As an industry standard with strong development capabilities, the UNIX operating system serves as an excellent foundation for MODCOMP's REAL/IX PX operating system. By implementing full kernel preemption, enhanced process scheduling, interprocess communications, as well as file system and I/O subsystem capabilities, the REAL/IX PX operating system delivers the predictable, deterministic response rates and fast context switch times required by real-time applications for event driven processing. Real-time applications demand CPU time be apportioned according to user-defined priorities. The REAL/IX PX operating system combines a fully preemptive kernel with 256 real-time and time-sharing scheduling priorities to control and allocate CPU processing. Time-critical processes are ensured immediate access to required system resources. Prompt, predictable response to internal and external events is required by real-time applications. Improved methods of interrupt handling and interprocess communication enable the REAL/IX PX operating system to offer extremely fast, deterministic response times. Processes in a real-time environment demand fast execution that is not compromised by disk I/O latency. File system enhancements enable the REAL/IX PX operating system to overlap disk I/O with CPU execution; at the same time, an improved I/O subsystem provides prioritized disk I/O. By reducing the overhead associated with disk I/O, the REAL/IX PX operating system delivers extremely fast file access. The REAL/IX PX operating system provides the TCP/IP protocol, allowing users to network systems via Ethernet interfaces. The feature allows users to transfer data quickly and easily among systems. Also, authorized users can log on to any system on the network. Additionally, user-written programs can access TCP/IP functions. Based on X11R5 and X11R6, the integral REAL/VU Graphical Environment provides industry-standard graphical user interfaces. In addition to the system console, a wide variety of networked graphics terminal devices are supported. A choice of several interfaces are provided, including the Open Software Foundation's (OSF), Motif environment. Another optional interface is one which resembles the Windows95 interface. The REAL/VU Graphical Environment makes code portable and users adaptable to different platforms. The Motif environment's widespread acceptance throughout the computer industry promotes code portability, preserving users' software investments. In addition, since the graphical interface is virtually identical regardless of the platform, once users become familiar with the Motif environment, they can easily transfer their skills among platforms. The REAL/VU Graphical Environment is easy to learn and easy to use. The user-friendly interface incorporates intuitively obvious pop-up and pull-down menus. The attractive and easy-to-read, three-dimensional screen appearance boosts user productivity. The user interface includes simplified log-in procedures and remote display management menus for the user's convenience. For enhanced user productivity, the REAL/VU Graphical Environment incorporates features for direct programmer support for focus management, context-specific help information, and the ability to perform most functions with either the keyboard or mouse. Offering quick response and efficient memory usage, the REAL/VU Graphical Environment provides high-speed performance even when users are working with large, cumbersome text files. The REAL/VU Graphical Environment includes a comprehensive set of tools, called widgets and gadgets. These tools make it easy for users to customize their environment to best suit the needs of their unique application. By following the guidelines for application programming that are included with the REAL/VU Graphical Environment, all customization can be done to conform to standards. The REAL/IX PX operating system is a full-featured bundled system. It comes with a complete C and C++ language development system. Items included are C and C++ compilers, linkers, libraries, assembler, and symbolic debugger. For enhanced usage in graphic-intensive applications, the REAL/IX PX operating system fully supports the X Window System for bit-mapped graphic display user interfaces. Using the REAL/IX PX operating system's integral REAL/VU Graphical Environment product, users can write applications to run with a wide variety of graphic devices. Because of its compliance to industry standards, the REAL/IX PX operating system enables the user to acquire and run many "shrink wrapped" applications available for Intel based UNIX System V operating system. These, combined with the REAL/IX PX operating system's real-time features and performance, provide the user with an unprecedented set of capabilities in a real-time system. Designed for PCI and ISA bus based systems utilizing the Intel X86 and Pentium microprocessors, the REAL/IX PX operating system conveys and enhances their architectural capabilities. Furthermore, the REAL/IX PX operating system balances the three dimensions of real-time computer performance: computational speed, interrupt handling, and I/O throughput. By maximizing performance in these three dimensions, the REAL/IX PX operating system delivers superior performance for real-time applications. The REAL/IX PX operating system provides transparent enhancements for all users. Time critical applications can make use of further enhancements specifically tailored for real-time programming.
Description The REAL/IX PX operating system incorporates many enhancements which address the requirements of real-time applications for user control and responsiveness.
Preemptive
kernel In conjunction with the fully preemptive kernel, the REAL/IX PX operating system incorporates an innovative locking mechanism to protect data structure integrity. These spin locks and suspend locks prevent corruption by ensuring that if one process is modifying a data structure, no other process can access that data structure until the modifications are complete. Low interrupt latency is critical to the performance in real-time applications, and the REAL/IX PX operating system meets these high-speed response requirements. From the time that a hardware interrupt signal occurs to the time that the kernel driver begins to process the event is less than 100 microseconds. Typically, the driver interrupt latency is in the 50 microsecond range on a 133 MHz Pentium based system.
Process
Scheduling Real-time priorities are assigned to processes at run-time and do not vary except by explicit control of the programmer or operator. Time-sharing priorities are assigned to the UNIX System V scheduling algorithm which ensures equitable access to system resources for non-real-time processes. The REAL/IX PX operating system also has a priority boost mechanism. This allows the priority of a process, which is locking a resource required by a higher priority process, to be temporarily raised until the resource is relinquished and made available for the more critical process. These process scheduling features allow the REAL/IX PX operating system to deliver the fast, predictable context switch times necessary for demanding real-time applications.
Multiprocessing The user can control the processor's load or allow the REAL/IX operating system to balance the load automatically. For users requiring complete control, any process can be targeted and locked to a specific processor. In addition, the user can direct interrupts to a specific processor, interrupting one process while having no effect on other processes in the multiprocessing environment.
Pre-page
and process memory locking
Interprocess
communications Signals are asynchronous messages sent from one process to another indicating that a specific condition has occurred. The REAL/IX PX operating system signal mechanism operates like the traditional UNIX signal mechanism, but with improved performance and reliability for the real-time environment. Shared memory, where multiple processes map the same area of memory into their address space, provides the fastest interprocess communication available within the REAL/IX PX operating system. Shared memory is accessed at the same speed as is a process' private memory. High performance binary semaphores provide the synchronization mechanisms required to make shared memory a viable, fast, inter-process communication facility. Common event notification enables the programmer to pre-define multiple event queues as well as event response procedures for each process. This provides accurate event reporting for processes responding to multiple events.
Real-time
timers System-wide timers provide applications with the ability to read, write, or obtain the resolution of a system timer. Process interval timers schedule events using a very fine granularity of time. Process interval timers are either one-shot or periodic, and can be set to expire at a specific time or at a time relative to the current system time.
File
system The standard file system provides all the features of the UNIX System V file system including: hierarchical organization for files and directories, buffering of data, and file access control. The fast file system includes all the functionality of the standard file system, while incorporating features that facilitate real-time performance by optimizing file access functions including:
The REAL/IX PX operating system supports large logical block sizes to improve the performance of block I/O transfers for large files. In addition, entire file systems can be designated as synchronous. In synchronous file systems, all write operations wait for the file data and file status to be physically updated, rather than waiting on for the write to the buffer cache.
ONC/NFS
I/O
subsystem By supporting asynchronous disk I/O operations, the REAL/IX PX operating system enables processing and disk I/O operations to overlap. This flexibility decreases overall process execution time. The REAL/IX PX operating system supports prioritized queueing of disk I/O, enabling disk I/O associated with higher priority processes to be performed before disk I/O associated with lower priority processes. Direct I/O enables a user program to map device registers into its own address space. System overhead associated with I/O is significantly reduced since the user program can directly access these registers. The connected interrupt mechanism provides a consistent interface for notifying user-level processes of hardware interrupts. The use of direct I/O with the connected interrupt mechanism enables a device driver to be implemented as a user level process. This configuration facilitates rapid interaction between the device and the process.
TCP/IP
protocol
User-extensible
kernel
Shells The REAL/IX PX operating system provides the user with two shells:
X
Window System The REAL/VU Graphical Environment, based on OSF/Motif Version 1.2, brings industry-standard, user-oriented, PC-style behavior and screen appearance to the real-time REAL/IX PX world. The REAL/VU Graphical Environment consists of the following:
Application
programming interface The user interface toolkit is based on the X11 Window System's Version 11 Release 6 Intrinsics. The toolkit includes a library of graphical objects, such as menus and forms, that users employ to construct application user interfaces. The toolkit contains dozens of basic, composite, scrolled, specialized composite, basic top-level, and specialized dialog widgets. Additionally, the toolkit contains windowless widgets, called gadgets. Gadgets perform specific functions with lower server overhead. In addition, gadgets can be grouped, or cached, and assigned the same attributes, such as color and font style. Grouped gadgets reduce memory requirements and significantly improve performance in complex applications. With the toolkit and a widget meta-language (WML), users can easily create new widgets, extend the functionality of existing widgets, or create new graphical objects suited to individual applications. The easy-to-use user interface language describes widget resources. With the user interface language, users create text files that describe each of the widgets, and its resources, that an application uses. Then, the REAL/VU Graphical Environment compiles the description into a resource file that is separate from the application. The application code automatically loads the resource file at runtime. By storing the resource file separately from the application code, the REAL/VU Graphical Environment simplifies the description and maintenance of user interfaces. Window
manager The window manager allows users to control multiple windows; for example, through the window manager, a user can move, resize, or add icons. The window manager controls the location of certain types of windows, overlapping windows, and the location of icons. The window manager supports three-dimensional, rectangular and non-rectangular, bevelled windows and both black and white and color windows. The window manager is compliant with the Inter-Client-Communication Conventions Manual (ICCCM), supporting selections, cut buffers, window and session management, and resources.
Style
guide The style guide includes information on Native Language Support (NLS) consistent with the X/Open XPG3 portability guide. NLS support and the user interface language enable the REAL/VU Graphical Environment to support international activities, including multiple languages and the localization of Asian and European languages. In addition to the style guide, this product includes a user's guide, a programmer's guide, and a reference manual. Suggested minimum hardware platform metrics:
Customer
support MODCOMP also offers flexible service programs tailored to the requirements of high volume customers, value added resellers (VAR's), original equipment manufacturers (OEM's), strategic marketing alliances (SMA's), and systems integrators (SI's). For further information on our customer support services and comprehensive technical training, please contact your local sales office or a MODCOMP customer support representative.
Support
category
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