3.5 Value

Each component element can have the following values:

When a value is set at a data terminal, the data terminal keeps that value in the immediate single machine cycle only. If no value is set in that machine cycle, the data terminal has "no value". If a data terminal with "no value" is referenced, the answer is "unknown".

When a value is set to a register or memory, the value is maintained until it is set again. If no value has ever been set (except for initialization by power-on/reset), the value is "unknown".

The result of an arithmetic operation between "unknown", "1" and "0" is as follows. Put "unknown" equal to first to "1" and then to "0". If the results are the same, then that result prevails. Otherwise, the result is "unknown".

The values of data terminal, register and memory are defined for each bit.

In each machine cycle, the value of a control terminal is "1", if it is activated, and "0", if it is not.

The value of a stage task is "1", if it is set, and "0", if it is not.

If a task that has been set is set again, it remains set. Only argument processing is affected. If a task is set and reset concurrently, set takes precedence.

If a control terminal is activated from multiple sources, the effect is the same as a single activation except for argument processing.

Since no errors occur even if a control terminal is activated from multiple sources, it can be used in communications involving multiple sender sources.

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