USBB17RX78K4-XXX NEC Electronics, USBB17RX78K4-XXX Datasheet - Page 10

• Manufacturer Part Number: USBB17RX78K4-XXX
• Description: 78K/4 series realtime OS
• Manufacturer: NEC Electronics

events. The conventional systems have tried to satisfy this requirement by using simple interrupt programs. As the
application systems have increasingly become high-performance and sophisticated, however, many problems that
cannot be solved only by simple interrupt programs have arisen.
executed has increased, it has been difficult to manage the execution sequence ofthe programs.
problem. The real-time OS immediately respond to changes in an event and executes the optimum programs in the
optimum sequence.
1.1 Multi-task OS
executing two or more tasks simultaneously on one CPU.
executed alternately, for example, at fixed time intervals, however, it seems to the human eye as if these tasks are
being executed at the same time.
execute tasks in parallel by selecting a task at specific opportunities is called a multi-task OS. A multi-task OS is
intended to improve the overall processing ability of the system processing tasks in parallel.
1.2 RX78K/IV
real-time/multi-task processing environment and to expand the application range of a targeted CPU in the control
equipment field, providing complete real-time/multi-task functions.
high execution speed OS, for implementation in ROM.
Systems in the field of control equipment are required to respond immediately to changes in external and internal
In other words, as systems have increasingly become complicated and as the quantity of the programs to be
The real-time operating system (hereafter referred to as the “real-time OS”) was developed to cope with this
The minimum unit that is executed under the management of the real-time OS is called a task. Multi-tasking is
Actually, however, the CPU can only execute one program at a time. If two or more tasks are selected and
The tasks are executed by taking advantage of opportunities such as time intervals. An OS that has a function to
The RX78K/IV is a real-time OS for embedded control applications and has been developed to supply an efficient
Because it is assumed that the RX78K/IV is embedded in the target system, it has been designed as a compact,
CHAPTER 1
GENERAL
1