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Looking for "Real-time Linux"?  See JMI's PSX.

C EXECUTIVE and PSXtm Real-time Kernels (RTOS)

C EXECUTIVE is a real-time, multi-tasking, ROMable kernel for embedded systems, and is available for 8-, 16- and 32-bit CISC processors, a wide variety of RISC processors, and DSP. It provides fast context switching, small kernel size, and support for over 20 processors. Optional DOS-compatible file system , TCP/IP , and SNMP are available. PSX provides an optional subset of POSIX.1 system calls.

PSX versus Linux

PSX provides a single-user, single-group subset of POSIX.1 system calls, and is about ONE TENTH the size of Linux, not to mention the much smaller interrupt latency. PSX does not have the overhead of fork/exec, MMU management and multi-user capability. Up to 32,000 processes and POSIX threads can be created. PSX is based on the C EXECUTIVE real-time kernel.

If a Linux-like resident and a DOS-compatible file system meet your needs, PSX may be the solution.


Both C EXECUTIVE and PSX are inherently scalable, since the system calls are linked in from a
library during a system build. Only those system calls which are used by the application are linked
into the system executable image. In addition, the kernel can be configured with or without timeslicing, clock support, signals, etc., allowing a highly optimized system configuration for small target systems.

Designing a System with C EXECUTIVE and PSX

JMI Software Systems is a strong proponent of data flow design. Please reference a description of our system design method.

i960 Reverse State Use - an example of optimization

JMI Software Systems is also a strong proponent of portable, reusable code (read "reliable"). JMI also pays special attention to optimizing the assembly language portions of our kernels, especially interrupt handling and context switching. Please see a description of JMI's Reverse State Use invention.

Customer Applications

JMI's real-time kernels are used in hundreds of embedded applications , including laser printers, electronic cash registers, medical instruments, communication devices, military and aerospace applications , and many other time critical systems. Pictures and descriptions of some customers' products are available in our product photo gallery.

Example Customer Products

A recent example of a customer product using C EXECUTIVE is the Paknet radio data network of Vodafone Data Network Ltd. This network provides radio data packet service throughout the UK,
using C EXECUTIVE running on 386 and 486 processors.

If you are interested in space missions using C EXECUTIVE, you may wish to refer to the
TERRIERS web site of Boston University, the GPS/MET web site maintained by the University Corporation for Atmospheric Research, or to an overview of OrbView-1 at the GPS Space Missions web site maintained by the University of New Brunswick. GPS/MET was built using a modified
Allen Osborne GPS receiver, which uses the 29000 version of C EXECUTIVE.

Another example of a customer product using C EXECUTIVE is the LogicDart from Hewlett-Packard. You may note that this product was featured on the cover of Embedded Systems Programming's 1998 Buyer's Guide, the de facto reference document for the embedded systems industry. This advanced logic probe uses the 80186 version of C EXECUTIVE to provide a powerful hand-held instrument for testing new microprocessor boards and other digital logic. This product won the Test Product of the Year award for 1998 as a "clear winner". You can also read about the LogicDart in the cover story of the March, 1998, issue of PennWell's Portable Design magazine. To get the full details on this product, check out Hewlett-Packard's LogicDart announcement.

Another example of a customer product using C EXECUTIVE is Padcom's SmartPath router. To learn more about this device, using C EXECUTIVE and CE-TCP on a 386EX, please refer to Padcom's web site .

Please come back to see more interesting JMI customers' products, including everything from cash registers to space satellites.


C EXECUTIVE and PSX are sold either on a one-time fee with no royalties, or, for small projects, on a sliding scale of per copy prices. Contact JMI for the pricing plan that meets your needs.

Training Course

JMI Software Systems, Inc. offers a standard training course for C EXECUTIVE and PSX.

Consulting Services

JMI Software Systems, Inc. offers consulting services for custom drivers and product extensions for C EXECUTIVE and PSX, as well as complete applications systems. Additional major consulting services are available through associated companies .

Contact Information

Corporate matters: The products of the former JMI Software Systems, Inc., are now owned by DLR Ventures.    Email: infotwo at jmisys.com

Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 JMI Software Systems, Inc.,  2008, 2011,2013  DLR Ventures

Web site last updated January 31, 2013.