applications      protocol                    output modules 
            interface      Speech Dispatcher core           synthesizers
                          .-----------------------.
|Emacspeak|    :s l:  < > |  Speech Dispatcher    | :m  :  |Apollo|
               :h i:  <S> |    - configuration    | :o  :  |Festival|
|Speakup|      :a b:  <S> | - synchronization     | :d A:  |Flite|
               :r r:  <I> |        - sound icons  | :u P:     .
|User center|  :e a:  <P> |  - history            | :l I:     .
      .        :d r:  < > |   - punctuation, ...  | :e  :     .
      .        :  y:  < > | [||| priority queues] | :   :     .
      .        :   :  < > |                       | :   :     .
                          `-----------------------'