324
9 OBDH Technology of Lunar Lander
Fig. 9.6 Architecture of onboard OBDH software
memory or more available external memory, and the operating system is installed
in a limited memory (usually ROM or FLASH) which is called an embedded operating system. Generally embedded operating system is composed of a very small
kernel and some system modules that can be customized according to requirements.
The characteristics of embedded operating system are small size, highly flexible,
real-time and multitasking. The embedded real-time operating system is a program
embedded in the object code and executed first after system reset, which is equivalent
to user’s resident program. Other user applications are built on the Real Time Multitask Operation System (RTOS). RTOS is a standard kernel that packs the resources
of CPU time, interrupt, I/O, timer and etc., which provides user with a standard API
interface and assigns CPU time reasonably among different tasks according to the
priority of each task. RTOS is an efficient, real-time multitasking kernel optimized
for different processors.
A real-time multitasking operating system is an operating system that can perform
specific functions within a specified time range or respond to external asynchronous
events. The results of session execution on the real-time operating system depend
on not only the correctness of logic judgments and logic calculations, but also on
the performing time of process. So the real-time operating system must be able to
ensure that its time requirement of process shall be satisfied, i.e., to ensure that the
specified task is completed within the required time.
The real time multitasking operation system provides operation interface for application software to complete real-time multitask concurrent scheduling of application
software. The operating system applies the architecture of micro kernel which has the
function of dynamic linking and downloading. It can support preemptive scheduling
and support priority rollover protocol. After the function, performance, reliability,
9 OBDH Technology of Lunar Lander
Fig. 9.6 Architecture of onboard OBDH software
memory or more available external memory, and the operating system is installed
in a limited memory (usually ROM or FLASH) which is called an embedded operating system. Generally embedded operating system is composed of a very small
kernel and some system modules that can be customized according to requirements.
The characteristics of embedded operating system are small size, highly flexible,
real-time and multitasking. The embedded real-time operating system is a program
embedded in the object code and executed first after system reset, which is equivalent
to user’s resident program. Other user applications are built on the Real Time Multitask Operation System (RTOS). RTOS is a standard kernel that packs the resources
of CPU time, interrupt, I/O, timer and etc., which provides user with a standard API
interface and assigns CPU time reasonably among different tasks according to the
priority of each task. RTOS is an efficient, real-time multitasking kernel optimized
for different processors.
A real-time multitasking operating system is an operating system that can perform
specific functions within a specified time range or respond to external asynchronous
events. The results of session execution on the real-time operating system depend
on not only the correctness of logic judgments and logic calculations, but also on
the performing time of process. So the real-time operating system must be able to
ensure that its time requirement of process shall be satisfied, i.e., to ensure that the
specified task is completed within the required time.
The real time multitasking operation system provides operation interface for application software to complete real-time multitask concurrent scheduling of application
software. The operating system applies the architecture of micro kernel which has the
function of dynamic linking and downloading. It can support preemptive scheduling
and support priority rollover protocol. After the function, performance, reliability,