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Chapter 2 General Information
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2.1 Objective of MR308 Development
In line with recent rapid technological advances in microcomputers, the functions of microcomputer-based
products have become complicated. In addition, the microcomputer program size has increased. Further, as
product development competition has been intensified, manufacturers are compelled to develop their micro-
computer-based products within a short period of time.
In other words, engineers engaged in microcomputer software development are now required to develop lar-
ger-size programs within a shorter period of time. To meet such stringent requirements, it is necessary to take
the following considerations into account.
1. To enhance software recyclability to decrease the volume of software to be developed.
One way to provide for software recyclability is to divide software into a number of functional modules
wherever possible. This may be accomplished by accumulating a number of general-purpose subrou-
tines and other program segments and using them for program development. In this method, however,
it is difficult to reuse programs that are dependent on time or timing. In reality, the greater part of ap-
plication programs are dependent on time or timing. Therefore, the above recycling method is applica-
ble to only a limited number of programs.
2. To promote team programming so that a number of engineers are engaged in the development
of one software package
There are various problems with team programming. One major problem is that debugging can be ini-
tiated only when all the software program segments created individually by team members are ready
for debugging. It is essential that communication be properly maintained among the team members.
3. To enhance software production efficiency so as to increase the volume of possible software
development per engineer.
One way to achieve this target would be to educate engineers to raise their level of skill. Another way
would be to make use of a structured descriptive assembler, C-compiler, or the like with a view toward
facilitating programming. It is also possible to enhance debugging efficiency by promoting modular
software development.
However, the conventional methods are not adequate for the purpose of solving the problems. Under these cir-
cumstances, it is necessary to introduce a new system named real-time OS
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To answer the above-mentioned demand, Renesas has developed a real-time operating system, tradenamed
MR308, for use with the M16C/70, 80 and M32C/80 series of 16/32-bit microcomputers .
When the MR308 is introduced, the following advantages are offered.
4. Software recycling is facilitated.
When the real-time OS is introduced, timing signals are furnished via the real-time OS so that pro-
grams dependent on timing can be reused. Further, as programs are divided into modules called tasks,
structured programming will be spontaneously provided.
That is, recyclable programs are automatically prepared.
5. Ease of team programming is provided.
When the real-time OS is put to use, programs are divided into functional modules called tasks.
Therefore, engineers can be allocated to individual tasks so that all steps from development to debug-
ging can be conducted independently for each task.
Further, the introduction of the real-time OS makes it easy to start debugging some already finished
tasks even if the entire program is not completed yet. Since engineers can be allocated to individual
tasks, work assignment is easy.
6. Software independence is enhanced to provide ease of program debugging.
As the use of the real-time OS makes it possible to divide programs into small independent modules
called tasks, the greater part of program debugging can be initiated simply by observing the small
modules.
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OS:Operating System