Example now enables the serial RX interrupt for echo

example.c

@@ -187,7 +187,8 @@ void timer_init(void) {
 
 	// Enable interrupts only for timer 0
 
-	IE = 0x82;
+	EA = 1;
+	ET0 = 1;
 }
 
 // Initializes the serial port (along with timer 2).
@@ -202,12 +203,14 @@ void serial_init(void) {
 	
 	SCON = 0x50;
 	TI = 1;
+	ES = 1;
 }
 
 // Writes a character to the serial port.
 void serial_putchar(char c) {
 	while(TI == 0);
 	SBUF = c;
+	TI = 0;
 }
 
 __bit stdout_to_lcd = 0;
@@ -317,3 +320,11 @@ void timer0_handler(void) __interrupt(1) {
 	if(TIMER != 0) TIMER--;
 }
 
+void serial_hanlder(void) __interrupt(4) {
+	if(RI) {
+		uint8_t data = SBUF;
+		serial_putchar(data);
+		RI = 0;
+	}
+}
+