Add built-in answer tones and automatic multiple-choice progression

main.c

@@ -49,7 +49,7 @@ static U8 title(void)
         text(8,149,"Choice: 1-4. Type: letters, spaces, Enter.",7);
         text(8,160,"Backspace edits. Near spelling: retry/reveal.",2);
         text(8,171,"50 questions. Release keys between presses.",2);
-        text(8,182,"Gold marks the state. SPACE after feedback.",6);
+        text(8,182,"Choice: auto next. Typed: SPACE to continue.",6);
         present();c=choose("12CQ");if(c=='C')credits();
     }while(c=='C');
     return c;
@@ -121,12 +121,24 @@ static U8 typed_answer(void)
         }
     }
 }
+static void answer_sound(U8 right)
+{
+    /* Color BASIC SOUND uses built-in audio and normal-speed timing.
+       Keep the graphics page visible while playing a rising or falling pair. */
+    setHighSpeed(FALSE);
+    if(right) {sound(170,2);sound(210,3);}
+    else {sound(100,3);sound(60,4);}
+    setHighSpeed(TRUE);
+}
 static void feedback(U8 right)
 {
     question_screen();phase=3;
     text(8,158,right?"CORRECT!":"NOT THIS TIME.",right?6:5);
     sprintf(line,"The capital is %s.",states[current_state].capital);text(8,170,line,7);
-    text(8,183,"Release your key, then SPACE to continue.",2);present();choose(" ");
+    text(8,183,mode==1?"Next question follows automatically.":"Release your key, then SPACE to continue.",2);
+    present();answer_sound(right);
+    if(mode==1) delay(90);  /* 1.5 seconds to read the answer after the tone. */
+    else choose(" ");
 }
 static U8 results(void)
 {