diff --git a/Makefile b/Makefile
index c36da57..e6c5225 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-SRC=main.c apr.c mem.c io.c
+SRC=main.c apr.c mem.c tty.c
 # clang
 #CFLAGS= -Wno-shift-op-parentheses -Wno-logical-op-parentheses \
 #        -Wno-bitwise-op-parentheses
diff --git a/apr.c b/apr.c
index 8f227e6..0acf261 100644
--- a/apr.c
+++ b/apr.c
@@ -1,5 +1,10 @@
 #include "pdp6.h"
 #include "inst.h"
+#include <unistd.h>
+
+word iobus0, iobus1;
+void (*iobusmap[128])(void);
+u8 ioreq[128];
 
 #define DBG_AR print("AR: %012llo\n", apr->ar)
 #define DBG_MB print("MB: %012llo\n", apr->mb)
@@ -7,7 +12,7 @@
 #define DBG_MA print("MA: %06o\n", apr->ma)
 #define DBG_IR print("IR: %06o\n", apr->ir)
 
-int dotrace = 1;
+int dotrace = 0;
 int pulsestepping = 0;
 Apr apr;
 
@@ -158,7 +163,6 @@ swap(word *a, word *b)
 #define IOT_CONI (apr->ir_iot && apr->io_inst == CONI)
 #define IOT_CONSZ (apr->ir_iot && apr->io_inst == CONSZ)
 #define IOT_CONSO (apr->ir_iot && apr->io_inst == CONSO)
-#define IOT_CONI (apr->ir_iot && apr->io_inst == CONI)
 #define IOT_BLK (apr->ir_iot && (apr->io_inst == BLKI || apr->io_inst == BLKO))
 #define IOT_OUTGOING (apr->ir_iot && (apr->io_inst == DATAO || apr->io_inst == CONO))
 #define IOT_STATUS (apr->ir_iot && \
@@ -172,7 +176,7 @@ decodeir(Apr *apr)
 	apr->io_inst = apr->ir & 0700340;
 
 	// 5-7
-	iobus1 &= ~037777000000;
+	iobus1 &= ~037777000000LL;
 	iobus1 |= apr->ir & H3 ? IOBUS_IOS3_1 : IOBUS_IOS3_0;
 	iobus1 |= apr->ir & H4 ? IOBUS_IOS4_1 : IOBUS_IOS4_0;
 	iobus1 |= apr->ir & H5 ? IOBUS_IOS5_1 : IOBUS_IOS5_0;
@@ -253,7 +257,7 @@ void
 ar_cry(Apr *apr)
 {
 	// 6-10
-	apr->ar_cry0_xor_cry1 = AR_OV_SET && ~MEMAC;
+	apr->ar_cry0_xor_cry1 = AR_OV_SET && !MEMAC;
 }
 
 void
@@ -341,7 +345,7 @@ recalc_req(void)
 	req = 0;
 	for(i = 0; i < 128; i++)
 		req |= ioreq[i];
-	iobus1 = iobus1&~0177 | req&0177;
+	iobus1 = iobus1&~0177LL | req&0177;
 }
 
 void
@@ -421,7 +425,7 @@ relocate(Apr *apr)
 		apr->rla += apr->rlr;
 
 	// 7-2, 7-10
-	membus0 &= ~0007777777761;
+	membus0 &= ~0007777777761LL;
 	membus0 |= ma_fmc_select ? MEMBUS_MA_FMC_SEL1 : MEMBUS_MA_FMC_SEL0;
 	membus0 |= (apr->ma&01777) << 4;
 	membus0 |= ((word)apr->rla&017) << 14;
@@ -1699,11 +1703,11 @@ pulse(fpt3){
 	apr->fe |= apr->sc;	// 6-15
 	apr->sc = 0;		// 6-15
 	// 6-3, 6-4
-	if(apr->mb & F0) apr->mb |= 0377000000000;
-	else             apr->mb &= ~0377000000000;
+	if(apr->mb & F0) apr->mb |= 0377000000000LL;
+	else             apr->mb &= ~0377000000000LL;
 	// 6-9, 6-4
-	if(apr->ar & F0) apr->ar |= 0377000000000;
-	else             apr->ar &= ~0377000000000;
+	if(apr->ar & F0) apr->ar |= 0377000000000LL;
+	else             apr->ar &= ~0377000000000LL;
 	nextpulse(apr, fpt4);	// 6-23
 }
 
@@ -2076,8 +2080,6 @@ pulse(pi_sync){
 		nextpulse(apr, iat0);		// 5-3
 	if(IA_NOT_INT)
 		nextpulse(apr, apr->if1a ? it1 : at1);	// 5-3
-	/* no longer needed */
-	apr->ia_inh = 0;
 }
 
 // 5-1
@@ -2411,6 +2413,9 @@ pulse(et1){
 	if(PI_RST)
 		clear_pih(apr);			// 8-4
 
+	// 6-3
+	if(apr->ir_acbm)
+		apr->mb &= apr->ar;
 	// 6-8
 	if(apr->ir_boole && (apr->ir_boole_op == 06 ||
 	                     apr->ir_boole_op == 011 ||
@@ -2432,9 +2437,6 @@ pulse(et1){
 	if(HWT_AR_0 || IOT_STATUS || IOT_DATAI)
 		apr->ar = 0;
 
-	// 6-3
-	if(apr->ir_acbm)
-		apr->mb &= ~apr->ar;
 	if(HWT_SWAP || FWT_SWAP || apr->inst == BLT)
 		SWAPLTRT(apr->mb);
 
@@ -3056,6 +3058,7 @@ aprmain(void *p)
 				if(c == 'x')
 					pulsestepping = 0;
 		}
+		//usleep(50000);
 
 		for(i = 0; i < apr->ncurpulses; i++)
 			apr->clist[i](apr);
@@ -3071,7 +3074,7 @@ aprmain(void *p)
 		if(apr->extpulse & 2){
 			apr->extpulse &= ~2;
 			apr->run = 0;
-			// cleared after PI SYNC
+			// hack: cleared when the pulse list was empty
 			apr->ia_inh = 1;
 		}
 
@@ -3097,6 +3100,10 @@ aprmain(void *p)
 			iobus1 &= ~IOBUS_PULSES;
 		}
 		if(iobus1 & IOBUS_IOB_RESET){
+			int d;
+			for(d = 0; d < nelem(iobusmap); d++)
+				if(iobusmap[d])
+					iobusmap[d]();
 			iobus1 &= ~IOBUS_IOB_RESET;
 		}
 
@@ -3124,8 +3131,14 @@ aprmain(void *p)
 			if(apr->mc_rq && !apr->mc_stop)
 				nextpulse(apr, mc_non_exist_mem);	// 7-9
 		}
-		if(i)
-			print("--------------\n");
+		if(i){
+		//	wakepanel();
+			trace("--------------\n");
+		}else{
+			/* no longer needed */
+			apr->ia_inh = 0;
+		}
+
 	}
 	print("power off\n");
 	return NULL;
diff --git a/io.c b/io.c
deleted file mode 100644
index ca7f7a6..0000000
--- a/io.c
+++ /dev/null
@@ -1,5 +0,0 @@
-#include "pdp6.h"
-
-word iobus0, iobus1;
-void (*iobusmap[128])(void);
-u8 ioreq[128];
diff --git a/main.c b/main.c
index ecef388..2110d8c 100644
--- a/main.c
+++ b/main.c
@@ -2,6 +2,8 @@
 #include <SDL/SDL.h>
 #include <SDL/SDL_image.h>
 #include <pthread.h>
+#include <time.h>
+#include <unistd.h>
 
 SDL_Surface *screen;
 
@@ -669,6 +671,18 @@ mouse(int button, int state, int x, int y)
 	}
 }
 
+void
+wakepanel(void)
+{
+	SDL_Event user_event;
+
+	user_event.type = SDL_USEREVENT;
+	user_event.user.code = 1;
+	user_event.user.data1 = NULL;
+	user_event.user.data2 = NULL;
+	SDL_PushEvent(&user_event);
+}
+
 int
 main()
 {
@@ -804,10 +818,25 @@ error:
 	rim_maint_sw->r.y += extra_panel.y;
 
 	initmem();
+	inittty();
 	memset(&apr, 0xff, sizeof apr);
 	apr.extpulse = 0;
 
+/*	int frm = 0;
+	time_t tm, tm2;
+	tm = time(nil);*/
 	for(;;){
+/*
+		frm++;
+		tm2 = time(nil);
+		if((tm2 - tm) > 5){
+			print("fps: %f\n", (float)frm/(tm2-tm));
+			tm = tm2;
+			frm = 0;
+		}
+*/
+//		usleep(1000);
+
 		while(SDL_PollEvent(&ev))
 			switch(ev.type){
 			case SDL_MOUSEMOTION:
@@ -825,6 +854,9 @@ error:
 				dumpmem();
 				SDL_Quit();
 				return 0;
+			case SDL_USEREVENT:
+				print("user\n");
+				break;
 			}
 		setlights(apr.ir, ir_lght, 18);
 		setlights(apr.mi, mi_lght, 36);
diff --git a/mem b/mem
index 1ce9ab0..63b9de9 100644
--- a/mem
+++ b/mem
@@ -1,11 +1,25 @@
-1000: 200000001011
-1001: 150000001012
-1002: 254200000000
-1003: 202400000000
-1004: 576400000000
-1005: 201600000000
-1006: 576200000000
-1007: 204500000000
-1010: 573300000000
-1011: 204600000000
-1012: 203400000000
+40: 254200000000
+41: 254200000000
+1000: 254000001102
+1101: 777700001000
+1102: 200740001101
+1103: 260740001112
+1104: 260740001120
+1105: 201000000012
+1106: 260740001120
+1107: 201000000141
+1110: 260740001120
+1111: 254200000000
+1112: 712240000000
+1113: 606000000040
+1114: 254000001112
+1115: 712040000000
+1116: 620000000200
+1117: 263740000000
+1120: 712240000001
+1121: 602040000020
+1122: 254000001120
+1123: 435000000200
+1124: 712140000000
+1125: 263740000000
+1126: 000000000141
diff --git a/op_panel.png b/op_panel.png
index 95b8f67..81717ff 100644
Binary files a/op_panel.png and b/op_panel.png differ
diff --git a/pdp6.h b/pdp6.h
index 0471a49..6089a44 100644
--- a/pdp6.h
+++ b/pdp6.h
@@ -13,7 +13,8 @@ typedef uint32_t hword;
 typedef uint32_t u32;
 typedef uint16_t u16;
 typedef uint8_t  u8;
-typedef char bool;
+typedef unsigned char uchar;
+typedef uchar bool;
 
 enum Mask {
 	FW   = 0777777777777,
@@ -96,7 +97,7 @@ enum {
 typedef struct Apr Apr;
 
 typedef void Pulse(Apr *apr);
-#define pulse(p) void p(Apr *apr)
+#define pulse(p) static void p(Apr *apr)
 
 struct Apr {
 	hword ir;
@@ -143,7 +144,8 @@ struct Apr {
 
 	bool cpa_iot_user, cpa_illeg_op, cpa_non_exist_mem,
 	     cpa_clock_enable, cpa_clock_flag, cpa_pc_chg_enable, cpa_pdl_ov,
-	     cpa_arov_enable, cpa_pia;
+	     cpa_arov_enable;
+	int cpa_pia;
 
 	bool iot_go;
 
@@ -270,6 +272,7 @@ enum {
 /* 0 is cable 1 & 2 (data); 1 is cable 3 & 4 (above bits) */
 extern word iobus0, iobus1;
 
+#define IOB_RESET       (iobus1 & IOBUS_IOB_RESET)
 #define IOB_DATAO_CLEAR (iobus1 & IOBUS_DATAO_CLEAR)
 #define IOB_DATAO_SET   (iobus1 & IOBUS_DATAO_SET)
 #define IOB_CONO_CLEAR  (iobus1 & IOBUS_CONO_CLEAR)
@@ -282,3 +285,8 @@ extern word iobus0, iobus1;
 extern void (*iobusmap[128])(void);
 /* current PI req for each device */
 extern u8 ioreq[128];
+void recalc_req(void);
+
+void inittty(void);
+
+//void wakepanel(void);
diff --git a/tty.c b/tty.c
new file mode 100644
index 0000000..2821ae3
--- /dev/null
+++ b/tty.c
@@ -0,0 +1,140 @@
+#include "pdp6.h"
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h> 
+#include <pthread.h>    
+#include <poll.h>
+
+/*
+ * This device is not accurately modeled after the schematics.
+ */
+
+#define TTY (0120>>2)
+
+typedef struct Tty Tty;
+struct Tty
+{
+	uchar tto, tti;
+	bool tto_busy, tto_flag;
+	bool tti_busy, tti_flag;
+	int pia;
+	int fd;
+};
+Tty tty;
+
+void
+recalc_tty_req(void)
+{
+	u8 req;
+	req = tty.tto_flag || tty.tti_flag ? tty.pia : 0;
+	if(req != ioreq[TTY]){
+		ioreq[TTY] = req;
+		recalc_req();
+	}
+}
+
+void*
+ttythread(void *arg)
+{
+	int sockfd, newsockfd, portno, clilen;
+	char buf;
+	struct sockaddr_in serv_addr, cli_addr;
+	int n;
+
+	sockfd = socket(AF_INET, SOCK_STREAM, 0);
+	if(sockfd < 0){
+		perror("ERROR opening socket");
+		exit(1);
+	}
+	memset(&serv_addr, 0, sizeof(serv_addr));
+	portno = 6666;
+	serv_addr.sin_family = AF_INET;
+	serv_addr.sin_addr.s_addr = INADDR_ANY;
+	serv_addr.sin_port = htons(portno);
+	if(bind(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0){
+		perror("ERROR on bind");
+		exit(1);
+	}
+	listen(sockfd,5);
+	clilen = sizeof(cli_addr);
+
+	pthread_t thread_id;
+	while(newsockfd = accept(sockfd, (struct sockaddr*)&cli_addr, &clilen)){
+		printf("TTY attached\n");
+		tty.fd = newsockfd;
+		while(n = read(tty.fd, &buf, 1), n > 0){
+			tty.tti = buf|0200;
+			tty.tti_flag = 1;
+			recalc_tty_req();
+		}
+		tty.fd = -1;
+		close(newsockfd);
+	}
+	if(newsockfd < 0){
+		perror("ERROR on accept");
+		exit(1);
+	}
+	return nil;
+}
+
+static void
+wake_tty(void)
+{
+	if(IOB_RESET){
+		tty.pia = 0;
+		tty.tto_busy = 0;
+		tty.tto_flag = 0;
+		tty.tto = 0;
+		tty.tti_busy = 0;
+		tty.tti_flag = 0;
+		tty.tti = 0;
+		ioreq[TTY] = 0;
+	}
+	if(IOB_STATUS){
+		if(tty.tti_busy) iobus0 |= F29;
+		if(tty.tti_flag) iobus0 |= F30;
+		if(tty.tto_busy) iobus0 |= F31;
+		if(tty.tto_flag) iobus0 |= F32;
+		iobus0 |= tty.pia & 7;
+	}
+	if(IOB_DATAI)
+		apr.ar = tty.tti;
+	if(IOB_CONO_CLEAR)
+		tty.pia = 0;
+	if(IOB_CONO_SET){
+		if(iobus0 & F25) tty.tti_busy = 0;
+		if(iobus0 & F26) tty.tti_flag = 0;
+		if(iobus0 & F27) tty.tto_busy = 0;
+		if(iobus0 & F28) tty.tto_flag = 0;
+		if(iobus0 & F29) tty.tti_busy = 1;
+		if(iobus0 & F30) tty.tti_flag = 1;
+		if(iobus0 & F31) tty.tto_busy = 1;
+		if(iobus0 & F32) tty.tto_flag = 1;
+		tty.pia |= iobus0 & 7;
+	}
+	if(IOB_DATAO_CLEAR)
+		tty.tto = 0;
+	if(IOB_DATAO_SET){
+		tty.tto = iobus0 & 0377;
+		tty.tto_busy = 1;
+		if(tty.tto & 0200 && tty.fd >= 0){
+			tty.tto &= ~0200;
+			write(tty.fd, &tty.tto, 1);
+		}
+		tty.tto_busy = 0;
+		tty.tto_flag = 1;
+	}
+	recalc_tty_req();
+}
+
+void
+inittty(void)
+{
+	pthread_t thread_id;
+	tty.fd = -1;
+	ioreq[TTY] = 0;
+	pthread_create(&thread_id, nil, ttythread, nil);
+	iobusmap[TTY] = wake_tty;
+}
diff --git a/ttytest.s b/ttytest.s
new file mode 100644
index 0000000..d7b1bb6
--- /dev/null
+++ b/ttytest.s
@@ -0,0 +1,43 @@
+P=17
+TTY=120
+
+
+PDLLEN=100
+
+.=40
+	JRST	4,
+	JRST	4,
+
+.=1000
+ENTRY:	JRST	START
+PDL:	.=.+PDLLEN
+SP:	-PDLLEN,,PDL-1
+
+START:
+	MOVE	P,SP
+	PUSHJ	P,GETCH
+	PUSHJ	P,PUTCHR
+	MOVEI	0,"\n
+	PUSHJ	P,PUTCHR
+	MOVEI	0,"a
+	PUSHJ	P,PUTCHR
+	JRST	4,
+
+GETCH:
+	CONI	TTY,0
+	TRNN	0,40
+	 JRST	.-2
+	DATAI	TTY,0
+	TRZ	0,200
+	POPJ	P,
+
+PUTCHR:
+	CONI	TTY,1
+	TRNE	1,20
+	 JRST	.-2
+	IORI	0,200
+	DATAO	TTY,0
+	POPJ	P,
+
+STR:
+	"a