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Trammell Hudson committed 889b7df

pd0 instead of jumper

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  * The KSR models use the 5-bit UART as well, but require a current loop
  * to generate the signal.  To wire this I used a 470 Ohm resistor:
  *
- *  TX+ --------------- Vcc (+5V)
+ *  TX+ --------------- PD0 with pullup (Vcc (+5V))
  *  TX- -----+--------- PD2 (uart rx)
  *           |
  *           +-/\/\/\-- GND
 #endif
 
 #ifdef CONFIG_UART
+	// drive D0 high to source current for RX current loop
+	ddr(0xD0, 1);
+	out(0xD0, 1);
+
 	// UBRR is 12 bits, max 4096.  So we run at 2 MHz
 	// to keep UBRR0 in range.
 	UBRR1 = 2749; // = 45.45 / (16 * 2 MHz) - 1