build hack with UART TX / RX support

06_IO_Devices/01_UartTX/hello.asm

@@ -2,3 +2,31 @@
 // this little assembler programm outputs "Hi" on UART_TX
 // 
 // Put your code here:
+//check tx status
+(START)
+@UART_TX
+D=M
+@SENDH
+D;JEQ
+@START
+0;JMP
+(SENDH)
+@72
+D=A
+@UART_TX
+M=D
+(WAIT)
+@UART_TX 
+D=M
+@SENDI
+D;JEQ
+@WAIT
+0;JMP
+(SENDI)
+@105
+D=A
+@UART_TX
+M=D
+(END)
+@END
+0;JMP