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3.
Introduction to Kernel
3.1 Concept of Real-time OS
This section explains the basic concept of real-time OS.
3.1.1
Why Real-time OS is Necessary
In line with the recent advances in semiconductor technologies, the single-chip microcomputer ROM capacity has in-
creased. ROM capacity of 32K bytes.
As such large ROM capacity microcomputers are introduced, their program development is not easily carried out by con-
ventional methods. Figure 3.1 shows the relationship between the program size and required development time (program
development difficulty).
This figure is nothing more than a schematic diagram. However, it indicates that the development period increases expo-
nentially with an increase in program size.
For example, the development of four 8K byte programs is easier than the development of one 32K byte program.
Program Size
Kbyte
4
8
16
32
Development Period
Figure 3.1 Relationship between Program Size and Development Period
Under these circumstances, it is necessary to adopt a method by which large-size programs can be developed within a short
period of time. One way to achieve this purpose is to use a large number of microcomputers having a small ROM capacity.
Figure 3.2 presents an example in which a number of microcomputers are used to build up an audio equipment system.
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On condition that the ROM program burning step need not be performed.
