The telecom module was operated remotely by a normal call from a phone. The
module used voice menus to provide information and offer the user choices, which he
could activate by pressing buttons on the phone keypad. The module used a standard
telecom chipset to recognize the frequencies of the DTMF tones and translate them
back into the simpler form of which button had been pressed.
The voice menus used real speech, sampled and stored in the module. As this was
an embedded device, the speech was broken down into reusable sampled units of
words or phrases to save memory. An actual sentence was played back as a sequence
of these samples.
Clients supplied a sketch of the desired voice menu, for example in simple ?¬‚ow
charts. These were ?¬‚eshed out by Domatic into a spreadsheet format which added the
technical details. For instance, sentences were broken down into sample units, and
the choices were implemented as jumps to another rowin the spreadsheet. Each rowof
the spreadsheet represented a certain memory address containing one primitive
command: play a certain voice sample, jump to a certain memory address, assign a
value to a register, and so on. Listing 7.1 shows the spreadsheet for a loop that reads out
all ?¬?ve modes in the system, and tells the user which button to press for each.
Listing 7.
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