Model erarchy o声 2… 画画) FIGURE 90.4 Software engineering methods overview. When a station selection button is momentarily depressed, the RBS causes a new station to be selected. Th selection is made on the basis of station-setting information stored within the RBS. The RBS can"memorize new station selections in the following manner: When a given station selection button is depressed longer tha momentary depressions of this button will result in this"memorized"station being selected. The RBS also performs a muting function. While a station is being selected, the rBS will cause the audio system to mute the audio output signal. The RBS will also cause the audio output signal to be muted until new station selection has been successfully memorized. The RBS interfaces with the front-panel station selection buttons by"reading a single-byte memory location Each bit position of this memory location is associated with a particular front-panel station selection button. The value of 0 in a given bit position indicates that the corresponding button is not depressed. The value of 1 in that bit position indicates that the corresponding button is depressed. For example, 0000 0000 indicates no station selection buttons are currently depressed; 0000 0010 indicates that the second button is currently resse The RBS interfaces with the tuning system by means of a common memory location. This single-byte memory location contains a non-negative integer value which represents a station selection.( For example, 0000 0000 might represent 87. 9 MHz, 0000 0001 might represent 88.1 MHz, etc. ) The RBS may "read"this memory location to"memorize"a current station selection. The RBS may also"write"to this memory location to cause the tuning system to select another station Finally, the RBS interfaces with the audio system by sending two signals. The RBS may send a MUTE-ON ignal to the audio system causing the audio system to disable the audio output. A MUTE-OFF signal would cause the audio system to enable the audio output. Information Modeling The construction of an information model is fundamental to so-called object-oriented approaches. An mation model captures a"view"of an application domain within a software system will be built Information models are based on entity-relationship diagrams and underlying textual information. A sample e 2000 by CRC Press LLC© 2000 by CRC Press LLC When a station selection button is momentarily depressed, the RBS causes a new station to be selected. This selection is made on the basis of station-setting information stored within the RBS. The RBS can “memorize” new station selections in the following manner: When a given station selection button is depressed longer than “momentarily” (say, for more than 2 seconds), the currently selected station will be “memorized.” Future momentary depressions of this button will result in this “memorized” station being selected. The RBS also performs a muting function. While a station is being selected, the RBS will cause the audio system to mute the audio output signal. The RBS will also cause the audio output signal to be muted until a new station selection has been successfully memorized. The RBS interfaces with the front-panel station selection buttons by “reading” a single-byte memory location. Each bit position of this memory location is associated with a particular front-panel station selection button. The value of 0 in a given bit position indicates that the corresponding button is not depressed. The value of 1 in that bit position indicates that the corresponding button is depressed. (For example, 0000 0000 indicates no station selection buttons are currently depressed; 0000 0010 indicates that the second button is currently depressed, etc.) The RBS interfaces with the tuning system by means of a common memory location. This single-byte memory location contains a non-negative integer value which represents a station selection. (For example, 0000 0000 might represent 87.9 MHz, 0000 0001 might represent 88.1 MHz, etc.) The RBS may “read” this memory location to “memorize” a current station selection. The RBS may also “write” to this memory location to cause the tuning system to select another station. Finally, the RBS interfaces with the audio system by sending two signals. The RBS may send a MUTE-ON signal to the audio system causing the audio system to disable the audio output. A MUTE-OFF signal would cause the audio system to enable the audio output. Information Modeling The construction of an information model is fundamental to so-called object-oriented approaches. An infor￾mation model captures a “view” of an application domain within which a software system will be built. Information models are based on entity-relationship diagrams and underlying textual information. A sample FIGURE 90.4 Software engineering methods overview