# Core API Calls

Call | Purpose
TextToSpeechStartup() (Windows) TextToSpeechStartup() (UNIX) | Initializes and starts up text-to-speech system. In Windows, the user defines the window handle to which post messages can be sent. In Tru64 UNIX, the user defines the callback routine. The calling application can then receive index marks, memory buffers, or status information through the above operating system dependent mechanism.
TextToSpeechStartupEx() | Initializes and starts up text-to-speech system. The user defines the callback routine that can be called when index marks, memory buffers, or status information needs to be sent to the calling application.
TextToSpeechSpeak() | Speaks text from a buffer.
TextToSpeechShutdown() | Shuts down the text-to-speech system.