diff --git a/ROM2/Makefile b/ROM2/Makefile
index 5ebabe26bb914c5f66885b03d2c18c54e6399fd1..17694c0539392854a45cfa7061aaecf12eaa7aa5 100644
--- a/ROM2/Makefile
+++ b/ROM2/Makefile
@@ -2,7 +2,7 @@
 
 OBJS = \
 	motors.o keypad.o display_basic.o coinmech.o chime.o \
-	helpers.o main_basic.o comm.o \
+	helpers.o main_basic.o sci.o \
 	vectors.o start.o
 INCLUDES = vend.h keypad.h chime.h asm.h display_basic.h ports.h types.h
 
diff --git a/ROM2/coinmech.c b/ROM2/coinmech.c
index d3b099205741042e7a6e9a914bc6ad7dc0f2ce87..124c8356ceea229f26bebc3cb52ca61b86c26ae4 100644
--- a/ROM2/coinmech.c
+++ b/ROM2/coinmech.c
@@ -51,7 +51,7 @@ void send_byte(u8 c) {
 }
 
 #define IS_CTRL(x) (x & 0x10) /* true if this packet is a control packet */
-void sci_interrupt() {
+void sci_interrupt_coinmech() {
 	u8 in;
 	in = _io_ports[M6811_SCDR];
 	
diff --git a/ROM2/main_basic.c b/ROM2/main_basic.c
index ae25a79390b385c49d07c30991d4fa9535368522..b2923bc11c8caaadef347e31755d20d0b9fd4bab 100644
--- a/ROM2/main_basic.c
+++ b/ROM2/main_basic.c
@@ -9,36 +9,36 @@
 #include "chime.h"
 #include "coinmech.h"
 #include "motors.h"
-#include "comm.h"
+#include "sci.h"
 #include "vend.h"
 
 void motor_reply(char* slotptr, u8 code) {
 	/* returns a message of the form MXYY - X is return code, YY is motor */
 	wait_for_tx_free();
-	tx_buffer[0] = 'M';
-	tx_buffer[1] = code + '0';
-	tx_buffer[2] = *slotptr;
-	tx_buffer[3] = *(slotptr+1);
-	tx_buffer[4] = '\n';
-	tx_buffer[5] = 0;
+	sci_tx_buf[0] = 'M';
+	sci_tx_buf[1] = code + '0';
+	sci_tx_buf[2] = *slotptr;
+	sci_tx_buf[3] = *(slotptr+1);
+	sci_tx_buf[4] = '\n';
+	sci_tx_buf[5] = 0;
 	send_packet();
 }
 
 void dispense_something() {
-	/* process a message VXX in msg_buf where XX is motor number */
+	/* process a message VXX in sci_rx_buf where XX is motor number */
 	u8 slot;
 
-	if ((msg_buf[1] < '0') || (msg_buf[1] > '9') ||
-		(msg_buf[2] < '0') || (msg_buf[2] > '9')) {
-		msg_buf[1] = msg_buf[2] = '0';
-		motor_reply((char*)&msg_buf[1], MOTOR_NOSLOT);
+	if ((sci_rx_buf[1] < '0') || (sci_rx_buf[1] > '9') ||
+		(sci_rx_buf[2] < '0') || (sci_rx_buf[2] > '9')) {
+		sci_rx_buf[1] = sci_rx_buf[2] = '0';
+		motor_reply((char*)&sci_rx_buf[1], MOTOR_NOSLOT);
 		return;
 	}
 
-	slot = (msg_buf[1] - '0') * 10;
-	slot += msg_buf[2] - '0';
+	slot = (sci_rx_buf[1] - '0') * 10;
+	slot += sci_rx_buf[2] - '0';
 
-	motor_reply((char*)&msg_buf[1], dispense_motor(slot));
+	motor_reply((char*)&sci_rx_buf[1], dispense_motor(slot));
 }
 
 void write_to_display() {
@@ -46,8 +46,8 @@ void write_to_display() {
 	u8 i;
 	char buf[10];
 	for (i = 0; i < 10; i++)
-		if (msg_buf[i+1])
-			buf[i] = msg_buf[i+1];
+		if (sci_rx_buf[i+1])
+			buf[i] = sci_rx_buf[i+1];
 		else
 			break;
 
@@ -60,33 +60,33 @@ void write_to_display() {
 
 void send_balance() {
 	wait_for_tx_free();
-	tx_buffer[0] = 'C';
-	tx_buffer[1] = have_change?'0':'1';
-	tx_buffer[2] = (coin_value/10000)%10;
-	tx_buffer[3] = (coin_value/1000)%10;
-	tx_buffer[4] = (coin_value/100)%10;
-	tx_buffer[5] = (coin_value/10)%10;
-	tx_buffer[6] = coin_value%10;
-	tx_buffer[7] = '\n';
-	tx_buffer[8] = 0;
+	sci_tx_buf[0] = 'C';
+	sci_tx_buf[1] = have_change?'0':'1';
+	sci_tx_buf[2] = (coin_value/10000)%10;
+	sci_tx_buf[3] = (coin_value/1000)%10;
+	sci_tx_buf[4] = (coin_value/100)%10;
+	sci_tx_buf[5] = (coin_value/10)%10;
+	sci_tx_buf[6] = coin_value%10;
+	sci_tx_buf[7] = '\n';
+	sci_tx_buf[8] = 0;
 	send_packet();
 }
 
 void give_change() {
 	u16 cost;
 
-	if ((msg_buf[1] < '0') || (msg_buf[1] > '9') ||
-		(msg_buf[2] < '0') || (msg_buf[2] > '9') ||
-		(msg_buf[3] < '0') || (msg_buf[3] > '9') ||
-		(msg_buf[4] < '0') || (msg_buf[4] > '9') ||
-		(msg_buf[5] < '0') || (msg_buf[5] > '9')) {
+	if ((sci_rx_buf[1] < '0') || (sci_rx_buf[1] > '9') ||
+		(sci_rx_buf[2] < '0') || (sci_rx_buf[2] > '9') ||
+		(sci_rx_buf[3] < '0') || (sci_rx_buf[3] > '9') ||
+		(sci_rx_buf[4] < '0') || (sci_rx_buf[4] > '9') ||
+		(sci_rx_buf[5] < '0') || (sci_rx_buf[5] > '9')) {
 		send_nack();
 	}
-	cost = msg_buf[1] - '0';
-	cost *= 10; cost = msg_buf[2] - '0';
-	cost *= 10; cost = msg_buf[3] - '0';
-	cost *= 10; cost = msg_buf[4] - '0';
-	cost *= 10; cost = msg_buf[5] - '0';
+	cost = sci_rx_buf[1] - '0';
+	cost *= 10; cost = sci_rx_buf[2] - '0';
+	cost *= 10; cost = sci_rx_buf[3] - '0';
+	cost *= 10; cost = sci_rx_buf[4] - '0';
+	cost *= 10; cost = sci_rx_buf[5] - '0';
 
 	coin_cost(cost);
 	send_ack();
@@ -95,22 +95,22 @@ void give_change() {
 void send_keypress(u8 key) {
 	/* send a packet of the form KX with X being the key, or R for reset */
 	wait_for_tx_free();
-	tx_buffer[0] = 'K';
+	sci_tx_buf[0] = 'K';
 	if (key == KEY_RESET)
-		tx_buffer[1] = 'R';
+		sci_tx_buf[1] = 'R';
 	else
-		tx_buffer[1] = (key%10)+'0';
-	tx_buffer[2] = '\n';
-	tx_buffer[3] = 0;
+		sci_tx_buf[1] = (key%10)+'0';
+	sci_tx_buf[2] = '\n';
+	sci_tx_buf[3] = 0;
 	send_packet();
 }
 
 void send_door_msg(bool open) {
 	wait_for_tx_free();
-	tx_buffer[0] = 'D';
-	tx_buffer[1] = open?'1':'0';
-	tx_buffer[2] = '\n';
-	tx_buffer[3] = 0;
+	sci_tx_buf[0] = 'D';
+	sci_tx_buf[1] = open?'1':'0';
+	sci_tx_buf[2] = '\n';
+	sci_tx_buf[3] = 0;
 	send_packet();
 }
 
@@ -121,20 +121,20 @@ void do_chime() {
 
 void ping_pong() {
 	/* make sure it's really a ping */
-	if (msg_buf[1] != 'I' ||
-		msg_buf[2] != 'N' ||
-		msg_buf[3] != 'G') {
+	if (sci_rx_buf[1] != 'I' ||
+		sci_rx_buf[2] != 'N' ||
+		sci_rx_buf[3] != 'G') {
 		send_nack();
 		return;
 	}
 	/* respond with ack & pong */
 	wait_for_tx_free();
-	tx_buffer[0] = 'P';
-	tx_buffer[1] = 'O';
-	tx_buffer[2] = 'N';
-	tx_buffer[3] = 'G';
-	tx_buffer[4] = '\n';
-	tx_buffer[5] = 0;
+	sci_tx_buf[0] = 'P';
+	sci_tx_buf[1] = 'O';
+	sci_tx_buf[2] = 'N';
+	sci_tx_buf[3] = 'G';
+	sci_tx_buf[4] = '\n';
+	sci_tx_buf[5] = 0;
 	send_packet();
 }
 
@@ -163,8 +163,9 @@ int main() {
 
 	unlock(); /* enable interrupts */
 
-	comm_init();
-	coinmech_init();
+	//comm_init();
+	//coinmech_init();
+	sci_init();
 	keypad_init();
 	last_coin_value = 0;
 	last_door_open = 0;
@@ -198,9 +199,8 @@ int main() {
 			}
 		}
 
-		/*
-		if (rx_queue_state) {
-			switch (msg_buf[0]) {
+		if (sci_have_packet) {
+			switch (sci_rx_buf[0]) {
 				case 'V':
 					dispense_something();
 					break;
@@ -226,7 +226,6 @@ int main() {
 			}
 			msg_clr();
 		}
-		*/
 
 		keypad_read();
 		if (keypad_pressed()) {
@@ -252,6 +251,9 @@ int main() {
 						case MOTOR_SUCCESS:
 							set_msg("THANK  YOU");
 							break;
+						case MOTOR_NOSLOT:
+							set_msg(" NO MOTOR ");
+							break;
 						default:
 							set_msg("ERRRRRRRR?");
 							break;
diff --git a/ROM2/motors.c b/ROM2/motors.c
index 64158ae56ab5e22b99ca93aae1123661cea2336f..13316ff610ff04030e7bca3e48f2e3c7cf6f81dd 100644
--- a/ROM2/motors.c
+++ b/ROM2/motors.c
@@ -73,19 +73,18 @@ void motors_off() {
 
 bool motor_here(u8 slot) {
 	u8 i, c = 0;
-	motor_on(slot);
 	for (i=0; i < 8; i++) {
+		motor_on(slot);
 		delay(5);
-		if (_io_ports[M6811_PORTE] & PORTE_MOTOR_OVERVOLTAGE) {
+		if ((_io_ports[M6811_PORTE] & PORTE_MOTOR_OVERVOLTAGE) == 0) {
 			c++;
-			if (c == 0xff) {
+			if (c == 3) {
 				motors_off();
 				return 1;
-			} else
-				continue;
+			}
 		}
+		motors_off();
 	}
-	motors_off();
 	return 0;
 }
 
@@ -95,49 +94,51 @@ bool is_motor(u8 slot) {
 }
 
 bool left_home(u8 slot) {
-	u8 i, r = slot%10;
+	u16 i;
+	u8 r = slot%10;
 	if (r >= 5) r--; 
 	r = 1 << (r-1);
-
-	for (i = 0; i < 5; i++)
+	for (i = 0; i < 1000; i++) {
 		if ((home_sensors & r) == 0) return 1;
-
+		delay(1);
+	}
 	/* it never left */
 	return 0;
 }
 
+#define is_overcurrent() ((_io_ports[M6811_PORTE] & PORTE_MOTOR_NOT_OVERCURRENT)==0)
+
 bool back_home(u8 slot) {
 	u8 i, r = slot%10;
 	if (r >= 5) r--; 
 	r = 1 << (r-1);
 
 	for (i = 0; i < 5; i++) {
-		if (home_sensors & r) return 1;
-		if ((_io_ports[M6811_PORTE] & PORTE_MOTOR_OVERCURRENT) == 0) return 1;
+		if ((home_sensors & r) != 0) return 1;
+		if (is_overcurrent()) return MOTOR_CURRENT_FAIL;
 	}
 
-	/* it never left */
+	/* it never arrived */
 	return 0;
 }
 
 bool motor_overcurrent() {
-	u8 t = 0, i = 0;
-	while(1) {
-		t++;
-		if (7 == t) return 1;
-		if (_io_ports[M6811_PORTE] & PORTE_MOTOR_OVERCURRENT) continue;
+	u8 good_passes = 0, t;
+	for (t = 0; t < 8; t++) {
+		delay(1);
+		if (is_overcurrent()) continue;
 		t = 0;
-		i++;
-		if (5 == i) return 0;
+		good_passes++;
+		if (good_passes == 5) return 0;
 	}
+	return 1;
 }
 
 u8 dispense_motor(u8 slot) {
-	//if (!is_motor(slot)) return MOTOR_NOSLOT;
+	if (!is_motor(slot)) return MOTOR_NOSLOT;
 
 	motor_on(slot);
-	delay(100);
-	
+
 	if (!left_home(slot)) {
 		motors_off();
 		return MOTOR_HOME_FAIL;
diff --git a/ROM2/sci.c b/ROM2/sci.c
index 39006bc0abc21277edfedba7e5a6be3e1660bfb6..3241f23c2cd971b34b6a31f7705ebfe8b5ab1426 100644
--- a/ROM2/sci.c
+++ b/ROM2/sci.c
@@ -1,11 +1,73 @@
 #include "vend.h"
 #include "sci.h"
 
+char sci_tx_buf[BUFFER_LEN];
+volatile char sci_rx_buf[BUFFER_LEN];
+volatile bool sci_have_packet;
+volatile u8 sci_rx_buf_ptr;
+
 void sci_init() {
-	_io_ports[M6811_BAUD] = M6811_DEF_BAUD;
+	/* assumes clock of 4.91Mhz */
+	_io_ports[M6811_BAUD] = 0x03; /* 9600 baud */
+
 	/* Setup character format 1 start, 8-bits, 1 stop.  */
 	_io_ports[M6811_SCCR1] = 0;
 
-	/* Enable reciever and transmitter.  */
-	_io_ports[M6811_SCCR2] = 0xc;
+	/* Enable reciever and transmitter & rx interrupt.  */
+	_io_ports[M6811_SCCR2] = 0x2c;
+
+	sci_have_packet = 0;
+	sci_rx_buf_ptr = 0;
+}
+
+void send_packet() {
+	char* c;
+	for (c = sci_tx_buf; *c; c++) {
+		/* wait for TX ready */
+		while (!(_io_ports[M6811_SCSR] & M6811_TDRE));
+
+		/* send byte */
+		_io_ports[M6811_SCDR] = *c;
+	}
+}
+
+void rx_int() {
+	if (sci_have_packet) return;
+	if (sci_rx_buf_ptr >= BUFFER_LEN) {
+		/* overrun :( */
+		sci_rx_buf[BUFFER_LEN] = '\0';
+		sci_have_packet = 1;
+		sci_rx_buf_ptr = 0;
+		return;
+	}
+	sci_rx_buf[sci_rx_buf_ptr] = _io_ports[M6811_SCDR];
+	if (sci_rx_buf[sci_rx_buf_ptr] == '\n') {
+		sci_rx_buf[sci_rx_buf_ptr] = '\0';
+		sci_have_packet = 1;
+		sci_rx_buf_ptr = 0;
+	}
+	sci_rx_buf_ptr++;
+}
+
+void msg_clr() {
+	sci_have_packet = 0;
+	sci_rx_buf_ptr = 0;
+}
+
+void sci_interrupt_serial() {
+	if (_io_ports[M6811_SCSR] & M6811_RDRF) rx_int();
+}
+
+void send_ack() {
+	sci_tx_buf[0] = '!';
+	sci_tx_buf[1] = '\n';
+	sci_tx_buf[2] = '\0';
+	send_packet();
+}
+
+void send_nack() {
+	sci_tx_buf[0] = '?';
+	sci_tx_buf[1] = '\n';
+	sci_tx_buf[2] = '\0';
+	send_packet();
 }
diff --git a/ROM2/sci.h b/ROM2/sci.h
index 80ac024336b4de35dd01787bf657a5e1bc6a5703..4b3a6d13d261ee22e70ce1d8f80e80da70862749 100644
--- a/ROM2/sci.h
+++ b/ROM2/sci.h
@@ -3,4 +3,17 @@
 
 #include "vend.h"
 
+#define BUFFER_LEN 12
+
+void sci_init();
+void msg_clr();
+void send_packet();
+void send_ack();
+void send_nack();
+#define wait_for_tx_free() do { } while(0)
+
+extern char sci_tx_buf[BUFFER_LEN];
+extern volatile char sci_rx_buf[BUFFER_LEN];
+extern volatile u8 sci_have_packet;
+
 #endif /* _SCI_H_ */
diff --git a/ROM2/vectors.s b/ROM2/vectors.s
index 14612df269028159ed9273d2d32d0f93a1fb3a8a..3ffb6a68d1c5d512827ebae52b514a86ec05b9e8 100644
--- a/ROM2/vectors.s
+++ b/ROM2/vectors.s
@@ -27,8 +27,9 @@ Boston, MA 02111-1307, USA.  */
 
 	.sect .text
 	.globl _start
-	.globl sci_interrupt
-	.globl uart_interrupt
+	.globl sci_interrupt_serial
+	.globl sci_interrupt_coinmech
+	;.globl uart_interrupt
 
 ;; Default interrupt handler.
 	.sect .text
@@ -67,7 +68,7 @@ vectors:
 	.word def		; ffd4
 
 	;; SCI
-	.word sci_interrupt	; ffd6
+	.word sci_interrupt_serial	; ffd6
 
 	;; SPI
 	.word def		; ffd8
@@ -90,7 +91,8 @@ vectors:
 	;;  Misc
 	;.word def	 	; fff0 (RTII) ; uncomment to disable the RTI & comment below
 	.word rti	 	; fff0 (RTII)
-	.word uart_interrupt	; fff2 (IRQ)
+	;.word uart_interrupt	; fff2 (IRQ)
+	.word def     	; fff2 (IRQ)
 	.word def		; fff4 (XIRQ)
 	.word def		; fff6 (SWI)
 	.word def		; fff8 (ILL)
diff --git a/ROM2/vend.h b/ROM2/vend.h
index 03d8c9e888266cd3bc856fe1cd363d74a94870ff..17ba674d1fd88c2deee12ec3b8692bde5283c997 100644
--- a/ROM2/vend.h
+++ b/ROM2/vend.h
@@ -41,7 +41,7 @@ void my_memcpy(char* dst, char* src, u8 size);
 
 #define PORTD_KEYPAD_ROW    0x20 /* clear for row 0, set for row 1 */
 
-#define PORTE_MOTOR_OVERCURRENT 0x01
+#define PORTE_MOTOR_NOT_OVERCURRENT 0x01
 #define PORTE_MOTOR_OVERVOLTAGE 0x02
 
 /* Address 1800 bits */
@@ -60,7 +60,8 @@ void my_memcpy(char* dst, char* src, u8 size);
 /******* from main.c *******/
 int __attribute__((noreturn)) main (void);
 void __attribute__((interrupt)) rti (void);
-void __attribute__((interrupt)) sci_interrupt (void);
+void __attribute__((interrupt)) sci_interrupt_serial (void);
+void __attribute__((interrupt)) sci_interrupt_coinmech (void);
 void __attribute__((interrupt)) uart_interrupt (void);
 
 /* other one liners */