IEEE 1003.13-2003 pdf download IEEE Standard for Information Technology— Standardized Application Environment Profile (AEP)—POSIX ® Realtime and Embedded Application Support
Rationale for Positioning (informative)1.2.1
(This subclause is not a normative part of IEEE Std 1003.13-2003.)This standard contains requirements for Application Program Interfaces andUnits of Functionality necessary to support four instances of the Generic RealtimeEnvironment class of applications. It specifies the behavior to be observed at theinterfaces of the Application Platform on which the class of applications can run.This subset of an Open System Environment (OSE) profile is complete andcoherent within the context of the class of applications supported. As such, it is aSystem Profile class of AEP
1.3 Realtime System Profiles
This standard describes four realtime profiles and their minimum hardwarerequlrements.
1.3.1 Minimal Realtime System Profile(PSE51)
PSE51 systems are typically embedded in larger systems dedicated to unattendedcontrol ofone or more special I/O devices. Neither user interaction nor a file system(mass storage) is required. The programming model is that of a single (implicit)
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POSIX process (corresponding to the processors hardware address space).containing one or more threads of control (POSIX.1 threads or Ada tasks).Although there is only one process, a Message Passing interface is provided forcommunications among threads of control and between PSE5X instantiationsSpecial devices are operated and controlled either by memory-mapped I/0 or by thebasic I/O interface, which provides a standard way to access the intrinsicallynonstandard I/O hardware and its nonportable control code.
The hardware model for this profile assumes a single processor with its memorybut no memory management unit (MMU) or common I/0 devices are required.(Ifthere are in fact multiple processors, typically there are multiple instantiations ofthe operating system,perhaps communicating via shared memory or a backplanechannel.perhaps isolated.)
1.3.2 Realtime Controller System Profile (PSE52)
These systems are an extension of the Minimal Realtime System Profile. Supportfor a file system interface and asynchronous (nonblocking) I/0 interfaces has beenadded.
The hardware model for this profile assumes a single processor and memory space(an MMU is not required). Mass storage devices are not required; the file systemmay, for instance, be implemented in memory (RAM disk or flash memory).
1.3.3 Dedicated Realtime System Profile (PSE53)
These systems are an extension of the Realtime Controller System Profile. Supportfor multiple processes has been added. Although these are usually embeddecsystems, flash memory technology enables presence of a simplified file system.even in those systems with mechanical or environmental requirements that preclude a rotating-media hard drive. Since memory management hardware may beprovided the functionality of memory locking is provided.
The hardware model for this profile assumes one or more processors, each with itsown MMU,in the same system.
1.3.4 Multi-Purpose Realtime System Profle (PSE54)
These systems include all the functionality ofthe other three profiles.They providecomprehensive functionality and run a mix of differing realtime and non-realtimetasks. This functionality includes most of POSIX.1 f31 and/or POSIX.5c f5.Since
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