The TextToSpeechStartup call attempts to find the entry for the DECtalk Software main pronunciation dictionary in the registry at:

REGISTRY KEY:

HKEY_LOCAL_MACHINE
\SOFTWARE\DigitalEquipmentCorporation\DECtalk\4.30

Value: MainDict

and is set to value:

[user selected dir]\system\dectalk.dic

If the MainDict entry cannot be found, then the TextToSpeechStartup call defaults to looking in the application’s default directory for DECTALK.DIC to be loaded as the main pronunciation dictionary.

If the main pronunciation dictionary fails to be loaded, then the TextToSpeechStartup call returns a value of MMSYSERR_ERROR.