From 88875b87ce1dfd458e2ba5f15f65b745a18d19f9 Mon Sep 17 00:00:00 2001
From: aap <aap@papnet.eu>
Date: Wed, 7 Feb 2018 01:37:09 +0100
Subject: [PATCH] committing old stuff

---
 code/Makefile      |  11 +-
 code/bootstrap.txt |  65 +++++
 code/dtboot.s      |  23 ++
 code/main.s        |  16 ++
 code/tty.s         |  23 ++
 emu/Makefile       |   2 +-
 emu/cmd.c          |  43 ++++
 emu/cmds.txt       |  18 ++
 emu/dc.c           |   5 +-
 emu/dt.c           | 577 +++++++++++++++++++++++++++++++++++++++++++++
 emu/init.ini       |   6 +
 emu/main.c         |   4 +-
 emu/mem.c          |   3 +-
 emu/mem_0          |  24 ++
 emu/pdp6.h         |  97 +++++++-
 misc/mkpty.c       |   3 +
 tools/ld6.c        |  18 +-
 17 files changed, 920 insertions(+), 18 deletions(-)
 create mode 100644 code/bootstrap.txt
 create mode 100644 code/dtboot.s
 create mode 100644 emu/cmds.txt
 create mode 100644 emu/dt.c
 create mode 100644 emu/mem_0

diff --git a/code/Makefile b/code/Makefile
index 9ccddcc..060babc 100644
--- a/code/Makefile
+++ b/code/Makefile
@@ -1,8 +1,11 @@
-test.rim: main.rel tty.rel pt.rel
-	ld6 -o test.rim main.rel tty.rel pt.rel
+test.rim: main.rel tty.rel pt.rel dt.rel
+	ld6 -o test.rim main.rel tty.rel pt.rel dt.rel
 
-test.sav: main.rel tty.rel pt.rel
-	ld6 -f sav -o test.sav main.rel tty.rel pt.rel
+test.sav: main.rel tty.rel pt.rel dt.rel
+	ld6 -f sav -o test.sav main.rel tty.rel pt.rel dt.rel
+
+dtboot.rim: dtboot.rel
+	ld6 -o dtboot.rim dtboot.rel
 
 %.rel: %.s
 	as6 -o $@ $<
diff --git a/code/bootstrap.txt b/code/bootstrap.txt
new file mode 100644
index 0000000..4db86a2
--- /dev/null
+++ b/code/bootstrap.txt
@@ -0,0 +1,65 @@
+PAPER TAPE RIM LOADER (AT 20):
+
+	LOC	20
+	CONO	PTR,60		; 710600 000060
+A:	CONSO	PTR,10		; 710740 000010
+	JRST	.-1		; 254000 000021
+	DATAI	PTR,B		; 710440 000026
+	CONSO	PTR,10		; 710740 000010
+	JRST	.-1		; 254000 000024
+B:	0			; 000000 000000
+	JRST	A		; 254000 000021
+
+DECTAPE RIM LOADER AT 0 (SHADOW) 014 INSTRUCTIONS
+
+MY DECTAPE LOADER:
+	CONO	DC,4010		; 720200 004010
+	CONO	UTC,220300	; 721200 220300
+	MOVE	17,12		; 200740 000012
+	CONSO	DC,1000		; 720340 001000
+	 JRST	.-1		; 254000 000003
+	BLKI	DC,17		; 720000 000017
+	 JRST	DONE		; 254000 000010
+	JRST	.-1		; 254000 000003
+DONE:	CONO	DC,0		; 720200 000000
+	HALT	300		; 254200 000300
+	777600000277		; 777600 000277
+
+
+PDP-10 RIM10 LOADER:
+
+003110' R1BLDR:
+000000 PHASE 0
+003110' 777762 000000 		IOWD $ADR,$ST
+003111' 710600 000060 $ST:	CONO PTR,60
+003112' 541400 000004 		HRRI $A,$RD+1
+003113' 710740 000010 $RD:	CONSO PTR,10
+003114' 254000 000003 		JRST .-1
+003115' 710470 000007 		DATAI PTR,@$TBL1-$RD+1($A)
+003116' 256010 000007 		XCT $TBL1-$RD+1($A)
+003117' 256010 000012 		XCT $TBL2-$RD+1($A)
+003120' 364400 000000 $A: 	SOJA $A,
+003121' 312740 000016 $TBL1:	CAME $CKSM,$ADR
+003122' 270756 000001 		ADD $CKSM,1($ADR)
+003123' 331740 000016 		SKIPL $CKSM,$ADR
+003124' 254200 000001 $TBL2:	JRST 4,$ST
+003125' 253700 000003 		AOBJN $ADR,$RD
+003126' 254000 000002 $ADR:	JRST $ST+1
+000017 $CKSM:
+003127' DEPHASE
+
+
+MAC DECtape RIM loader:
+000000	JFCL
+000001	MOVSI	(JFCL)
+000002	CONO	635550
+000003	CONO	PI,11577
+000004	CONO	UTC,223110
+000005	CONO	DC,4010
+000006	CONSO	DC,1000
+000007	JRST	6
+000010	DATAI	DC,13
+000011	AOJGE	13,6
+000012	TRNE	13,-1
+000013	.
+000014	JRST	6
diff --git a/code/dtboot.s b/code/dtboot.s
new file mode 100644
index 0000000..b5efae2
--- /dev/null
+++ b/code/dtboot.s
@@ -0,0 +1,23 @@
+DC==200
+UTC==210
+UTS==214
+
+DACI==04010
+
+SL==220000
+RD==300
+
+LOC	0
+ENTRY:
+	CONO	DC,DACI
+	CONO	UTC,SL+RD
+	MOVE	17,[ IOWD 200,300 ]
+	CONSO	DC,1000
+	 JRST	.-1
+	BLKI	DC,17
+	 JRST	DONE
+	JRST	.-4
+DONE:	CONO	DC,0
+	HALT	300
+
+END ENTRY
diff --git a/code/main.s b/code/main.s
index 79de70b..2453ee8 100644
--- a/code/main.s
+++ b/code/main.s
@@ -10,7 +10,9 @@ PTP==100
 
 EXTERN PUTC,PUTS
 EXTERN GETCH,GETC
+EXTERN PUTN
 EXTERN PTPUT
+EXTERN DTTEST
 
 ENTRY:	JRST	START
 
@@ -19,16 +21,30 @@ SP:	XWD	-100,PDL-1
 
 START:	MOVE	PDP,SP
 
+	;; NUMBER TEST
+;	MOVE	AC1,[-1234]
+;	PUSHJ	PDP,PUTN
+;	MOVE	AC1,[1234]
+;	PUSHJ	PDP,PUTN
+
+	;; DECTAPE TEST
+	JRST	DTTEST
+
+	;; UUO TEST
 ;	UUO1	123
 
+	;; ENABLE CLOCK PI ON CHANNEL 1
 ;	CONO	CPA,2001
+	;; ENABLE PI ON CHANNEL 1
 ;	CONO	PRS,2300
 ;	JRST	.
 
+	;; WRITE MESSAGE TO TTY
 	MOVSI	AC2,440700
 	HRRI	AC2,MSG
 	PUSHJ	PDP,PUTS
 
+	;; WRITE FROM TTY TO PTP
 	PUSHJ	PDP,GETC
 ;	CONO	PTP,20
 	PUSHJ	PDP,PTPUT
diff --git a/code/tty.s b/code/tty.s
index f17123f..ceb7e22 100644
--- a/code/tty.s
+++ b/code/tty.s
@@ -7,6 +7,7 @@ PDP==17
 
 INTERNAL PUTC,PUTS
 
+; PRINT CHAR IN AC1 ON TTY
 PUTC:
 	CONSZ	TTY,20		; wait until not busy
 	 JRST	.-1
@@ -31,6 +32,7 @@ PUTS:
 
 INTERNAL GETCH,GETC
 
+; READ CHAR FROM TTY INTO AC1
 GETCH:
 	CONSO	TTY,40		; wait for flag
 	 JRST	.-1
@@ -42,3 +44,24 @@ GETC:
 	PUSHJ	PDP,GETCH
 	PUSHJ	PDP,PUTC
 	POPJ	PDP,
+
+BASE:	10
+DIGITS:	EXP "0", "1", "2", "3", "4", "5", "6", "7", "8", "9"
+; PRINT NUMBER IN AC!
+INTERNAL PUTN
+PUTN:
+	JUMPGE	AC1,UPUTN
+	PUSH	PDP,AC1
+	MOVEI	AC1, "-"
+	PUSHJ	PDP,PUTC
+	POP	PDP,AC1
+	MOVM	AC1,AC1
+UPUTN:
+	IDIV	AC1,BASE
+	JUMPE	AC1,UPR1
+	PUSH	PDP,AC2
+	PUSHJ	PDP,UPUTN
+	POP	PDP,AC2
+UPR1:
+	MOVE	AC1,DIGITS(AC2)
+	JRST	PUTC
diff --git a/emu/Makefile b/emu/Makefile
index 23da7ad..930c186 100644
--- a/emu/Makefile
+++ b/emu/Makefile
@@ -1,4 +1,4 @@
-SRC=main.c cmd.c apr.c mem.c tty.c pt.c dc.c ../tools/pdp6common.c
+SRC=main.c cmd.c apr.c mem.c tty.c pt.c dc.c dt.c ../tools/pdp6common.c
 H=pdp6.h ../tools/pdp6common.h
 # clang
 #CFLAGS= -Wno-shift-op-parentheses -Wno-logical-op-parentheses \
diff --git a/emu/cmd.c b/emu/cmd.c
index 75b0023..be5a406 100644
--- a/emu/cmd.c
+++ b/emu/cmd.c
@@ -211,6 +211,8 @@ DevDef definitions[] = {
 	{ PTR_IDENT, makeptr },
 	{ PTP_IDENT, makeptp },
 	{ DC_IDENT, makedc },
+	{ DT_IDENT, makedt },
+	{ DX_IDENT, makedx },
 	{ nil, nil }
 };
 
@@ -318,6 +320,44 @@ c_memconnect(int argc, char *argv[])
 	attachmem((Mem*)dev, proc, &((Apr*)busdev)->membus, addr);
 }
 
+/* devconnect dev1 dev2 */
+// TODO: not quite sure this is the right way to do it
+static void
+c_devconnect(int argc, char *argv[])
+{
+	Device *dev1, *dev2;
+
+	if(argc < 3){
+args:
+		printf("Not enough arguments\n");
+		return;
+	}
+	dev1 = getdevice(argv[1]);
+	if(dev1 == nil){
+		printf("No device: %s\n", argv[1]);
+		return;
+	}
+	dev2 = getdevice(argv[2]);
+	if(dev2 == nil){
+		printf("No device: %s\n", argv[2]);
+		return;
+	}
+	if(dev1->type == dc_ident && dev2->type == dt_ident)
+		dtconn((Dc136*)dev1, (Dt551*)dev2);
+	else if(dev1->type == dt_ident && dev2->type == dx_ident){
+		int n;
+		if(argc < 4)
+			goto args;
+		n = atoi(argv[3]);
+		if(n < 1 || n > 8){
+			printf("Invalid device number %d\n", n);
+			return;
+		}
+		dxconn((Dt551*)dev1, (Dx555*)dev2, n);
+	}else
+		printf("Cannot connect %s to %s\n", dev2->type, dev1->type);
+}
+
 static void
 c_ex(int argc, char *argv[])
 {
@@ -423,6 +463,8 @@ c_load(int argc, char *argv[])
 static void
 c_show(int argc, char *argv[])
 {
+	printf("Devices:\n");
+	showdevices();
 	printf("Memory:\n");
 	showmem(&apr->membus);
 }
@@ -441,6 +483,7 @@ struct {
 	{ "attach", c_attach },
 	{ "ioconnect", c_ioconnect },
 	{ "memconnect", c_memconnect },
+	{ "devconnect", c_devconnect },
 	{ "examine", c_ex },
 	{ "deposit", c_dep },
 	{ "load", c_load },
diff --git a/emu/cmds.txt b/emu/cmds.txt
new file mode 100644
index 0000000..08860ed
--- /dev/null
+++ b/emu/cmds.txt
@@ -0,0 +1,18 @@
+mkdev name type
+	creates a device and gives it a name
+attach name path
+	attaches a file to a device
+ioconnect name busdevname
+	connects a device to the IO bus of a processor
+memconnect name procnum busdevname addr
+	connects a memory module to the memory bus of a processor
+examine [-sm] address(range)
+	examines memory (s: shadow mode, m: mnemonic)
+deposit [-sm] address(range) word
+	deposits word into memory (s: shadow mode, m: mnemonic)
+load filename
+	loads file into memory (see source for which format)
+show
+	shows device configuration
+quit
+	take a guess
diff --git a/emu/dc.c b/emu/dc.c
index ef36b14..a25e9d3 100644
--- a/emu/dc.c
+++ b/emu/dc.c
@@ -47,6 +47,7 @@ cp0:
 
 	// DASH CP1
 	if(DC_CCT_DONE){
+//printf("Full DA: %012lo\n", dc->da);
 		dc->cct = 0;
 		if(dc->da_rq == 0){
 			dc->da_rq = 1;
@@ -73,8 +74,9 @@ cp0:
 }
 
 void
-dcgv(Dc136 *dc, word c, int n, int rev)
+dcgv(Dc136 *dc, int n, word c, int rev)
 {
+//printf("DC Taking %06lo from dev %d\n", c, n);
 	switch(n){
 	case 1: case 2:
 		if(rev)
@@ -121,6 +123,7 @@ dctk(Dc136 *dc, int n, int rev)
 	}
 	dash_cp0(dc);
 	recalc_dc_req(dc);
+//printf("DC Giving %06lo to dev %d\n", c, n);
 	return c;
 }
 
diff --git a/emu/dt.c b/emu/dt.c
new file mode 100644
index 0000000..9df883c
--- /dev/null
+++ b/emu/dt.c
@@ -0,0 +1,577 @@
+#include "pdp6.h"
+#include <fcntl.h>
+#include <unistd.h>
+
+char *dt_ident = DT_IDENT;
+char *dx_ident = DX_IDENT;
+
+// TODO: find out how this should be controlled
+#define DEVNO 1
+
+enum
+{
+	DTSIZE = 922512
+};
+
+/* Transport */
+
+static uchar
+dxread(Dx555 *dx)
+{
+	if(dx->dt->ut_rev)
+		return *dx->cur ^ 010;
+	else
+		return *dx->cur;
+}
+
+static void
+dxwrite(Dx555 *dx, uchar d)
+{
+	if(dx->dt->ut_rev)
+		*dx->cur = d ^ 010;
+	else
+		*dx->cur = d;
+}
+
+static void
+dxmove(Dx555 *dx)
+{
+	// At end of tape read the last word forever
+	if(dx->dt->ut_rev){
+		dx->cur--;
+		if(dx->cur < dx->start)
+			dx->cur = dx->start+5;
+	}else{
+		dx->cur++;
+		if(dx->cur >= dx->end)
+			dx->cur = dx->end-6;
+	}
+}
+
+static void
+dxattach(Device *dev, const char *path)
+{
+	Dx555 *dx;
+	int fd;
+
+	dx = (Dx555*)dev;
+	fd = dx->fd;
+	if(fd >= 0){
+		dx->fd = -1;
+		close(dx->fd);
+	}
+	memset(dx->start, 0, DTSIZE);
+	dx->fd = open(path, O_RDWR | O_CREAT, 0666);
+	if(dx->fd < 0)
+		fprintf(stderr, "couldn't open file %s\n", path);
+	else
+		read(dx->fd, dx->start, DTSIZE);
+}
+
+/* Connect a transport to a control */
+void
+dxconn(Dt551 *dt, Dx555 *dx, int n)
+{
+	dt->dx[n%8] = dx;
+	dx->dt = dt;
+	dx->unit = n;
+}
+
+Device*
+makedx(int argc, char *argv[])
+{
+	Dx555 *dx;
+
+	dx = malloc(sizeof(Dx555));
+	memset(dx, 0, sizeof(Dx555));
+
+	dx->dev.type = dx_ident;
+	dx->dev.name = "";
+	dx->dev.attach = dxattach;
+	dx->dev.ioconnect = nil;
+
+	dx->start = malloc(DTSIZE);
+	dx->cur = dx->start;
+	dx->end = dx->start + DTSIZE;
+	memset(dx->start, 0, DTSIZE);
+
+	return &dx->dev;
+}
+
+/* Control */
+
+enum
+{
+	TapeEndF  = 022,
+	TapeEndR  = 055,
+
+	BlockSpace = 025,
+
+	BlockEndF = 026,
+	BlockEndR = 045,
+
+	DataSync  = 032,	/* rev guard */
+	BlockSync = 051,	/* guard */
+
+	DataEndF  = 073,	/* pre-final, final, ck, rev lock */
+	DataEndR  = 010,	/* lock, rev ck, rev final, rev pre-final */
+
+	Data = 070,
+
+
+	RW_NULL   = 0,
+	RW_RQ     = 1,
+	RW_ACTIVE = 2,
+};
+
+#define DATA_SYNC (dt->tmk == (0600|DataSync))
+#define END_ZONE (dt->tmk == (0600|TapeEndF))
+#define BM_SPACE (dt->tmk == (0400|BlockSpace) ||\
+		dt->tmk == (0500|BlockSpace) ||\
+		dt->tmk == (0600|BlockSpace) ||\
+		dt->tmk == (0700|BlockSpace))
+#define BM_END (dt->tmk == (0500|BlockEndF))
+#define DATA_SYNC (dt->tmk == (0600|DataSync))
+#define BM_SYNC (dt->tmk == (0700|BlockSync))
+#define FWD_DATA_END (dt->tmk == (0400|DataEndF) ||\
+		dt->tmk == (0700|DataEndF))
+#define REV_DATA_END (dt->tmk == (0400|DataEndR) ||\
+		dt->tmk == (0600|DataEndR))
+#define DATA (dt->tmk == (0400|Data))
+
+#define STOP (dt->tdata == 0 || dt->tdata == 1)
+#define SYNC (dt->tdata == 0200)
+#define REV_CKS (dt->tdata == 0100)
+#define BLOCK (dt->tdata == 040 || dt->tdata == 020 || dt->tdata == 010)
+#define PRE_FINAL (dt->tdata == 004)
+#define FWD_CKS (dt->tdata == 002)
+
+#define UT_WRITE ((dt->ut_fcn & 04) == 04)
+#define UT_READ ((dt->ut_fcn & 04) == 0)
+#define UT_ALL ((dt->ut_fcn & 03) == 01)
+#define UT_BM ((dt->ut_fcn & 03) == 02)
+#define UT_DATA ((dt->ut_fcn & 03) == 03)
+#define UT_DN (dt->ut_fcn == 0)
+#define UT_WRTM (dt->ut_fcn == 04)
+
+#define DC_SELECT1 (dt->dc->devp[dt->dc->device] == dt)
+#define UTE_DC_DISCONNECT (!(DC_SELECT1 && !dt->dc->da_rq))
+#define UT_WRITE_PREVENT (dt->seldx->wrlock)
+#define UT_WREN_DATA (UT_WRITE && dt->ut_wren && !UT_WRITE_PREVENT)
+#define RW_ODD (!dt->tct && dt->rw_state == RW_ACTIVE)
+#define RW_BM_DONE (UT_BM && BM_END)
+#define RW_DATA_CONT (DC_SELECT1 && !dt->dc->da_rq && UT_DATA && dt->rw_state == RW_ACTIVE)
+#define RW_DATA_STOP (UTE_DC_DISCONNECT && UT_DATA && dt->rw_state == RW_ACTIVE)
+
+#define TBM0 (dt->tbm == 10)
+#define TBM3 (dt->tbm == 1)
+
+// all but block space
+#define UTE_MK (DATA_SYNC || END_ZONE || BM_END ||\
+	DATA_SYNC || BM_SYNC || FWD_DATA_END || REV_DATA_END || DATA)
+#define UTE_ERROR (dt->uteck && (dt->utek == 040) != UTE_MK)
+// not sure if BM SYNC || DATA SYNC is correct
+#define UTE_ACTIVE_ERROR (!UT_ALL && dt->rw_state == RW_ACTIVE && (BM_SYNC || DATA_SYNC))
+
+
+
+#define PRINT1 \
+	printf("%c%02o(%o,%02o,%d)", dt->rw_state == RW_ACTIVE ? '+' : dt->rw_state == RW_RQ ? '-' : ' ', \
+		dt->tmk&077, l&07, dt->rwb, dt->tct); \
+	putchar(' '); \
+	if(STOP) \
+		printf(" [STOP] "); \
+	else if(SYNC) \
+		printf(" [SYNC] "); \
+	else if(REV_CKS) \
+		printf(" [REV_CKS] "); \
+	else if(BLOCK) \
+		printf(" [BLOCK] "); \
+	else if(PRE_FINAL) \
+		printf(" [PRE FINAL] "); \
+	else if(FWD_CKS) \
+		printf(" [FWD CKS %02o] ", dt->lb);
+
+#define PRINT2 \
+	if(END_ZONE) \
+		printf("TapeEndF "); \
+	else if(BM_SPACE) \
+		printf("BlockSpace %o ", dt->tbm); \
+	else if(BM_END) \
+		printf("BlockEndF "); \
+	else if(DATA_SYNC) \
+		printf("DataSync "); \
+	else if(BM_SYNC) \
+		printf("BlockSync "); \
+	else if(FWD_DATA_END) \
+		printf("DataEndF "); \
+	else if(REV_DATA_END) \
+		printf("DataEndR "); \
+	else if(DATA) \
+		printf("Data ");
+
+static void
+recalc_dt_req(Dt551 *dt)
+{
+	int req;
+	if(dt->ut_jb_done_flag && dt->ut_jb_done_enable ||
+	   dt->ut_tape_end_flag && dt->ut_tape_end_enable ||
+	   dt->time_flag && dt->time_enable ||
+	   dt->ut_info_error ||
+	   dt->ut_illegal_op)
+		req = dt->ut_pia;
+	else
+		req = 0;
+	setreq(dt->bus, UTC, req);
+}
+
+static void
+dtcycle(void *p)
+{
+	Dt551 *dt;
+	dt = (Dt551*)p;
+	uchar l, wb;
+	int data1edge, data7edge;
+	int bm0edge, bm3edge;
+
+	// TODO: maybe do something else here?
+	if(dt->seldx == nil)
+		return;
+
+	if(!dt->ut_go)
+		return;
+
+
+	if(dt->rw_state != RW_ACTIVE)
+		dt->tct = 0;
+	l = dxread(dt->seldx);
+
+/* TP0 */
+
+	if(dt->rw_state == RW_ACTIVE)
+		dt->ut_wren = 1;
+
+	if(UT_WRITE){
+		if(UT_WRITE_PREVENT)
+			dt->ut_illegal_op = 1;
+		if(dt->tct)
+			wb = l&010 | dt->rwb&07;
+		else
+			wb = l&010 | dt->rwb>>3 & 07;
+	}
+	if(UT_WREN_DATA)
+		dxwrite(dt->seldx, wb);
+
+/* TP1 */
+
+//**/				PRINT1
+//**/				PRINT2
+
+	dt->tmk = ((dt->tmk << 1) | !!(l&010)) & 0377 |
+		dt->tmk&0400 | (dt->tmk<<1)&0400;
+	if(UT_READ){
+		if(dt->tct != dt->ut_rev)
+			dt->rwb |= l&07;
+		else
+			dt->rwb |= (l&07) << 3;
+	}
+
+/* TP2 */
+///**/				printf("%2o%c%c%c  ", dt->utek, UTE_MK ? 'M' : ' ', UTE_ERROR ? 'E' : ' ', dt->uteck ?  'C' : ' ');
+
+	if(UTE_ERROR || UTE_ACTIVE_ERROR)
+printf("UT INFO ERROR\n"),
+		dt->ut_info_error = 1;
+
+	if(!BM_SPACE){
+		if(dt->utek == 1)
+			dt->utek = 040;
+		else
+			dt->utek >>= 1;
+	}
+
+	if(dt->tct)
+		dt->lb ^= ~dt->rwb & 077;
+
+//**/			if(dt->rw_state == RW_ACTIVE && dt->tct)
+//**/				printf("(%02o, %02o) ", dt->rwb, dt->lb);
+
+	if(UT_READ && dt->rw_state == RW_ACTIVE && dt->tct){
+		// before tct complement
+		if(!(UT_DATA && dt->tdata & 0102)){
+			dcgv(dt->dc, DEVNO, dt->rwb, dt->ut_rev);
+			if(UTE_DC_DISCONNECT)
+				dt->ut_incomp_block = 1;
+		}
+	}
+
+
+	if(END_ZONE){
+		dt->ut_tape_end_flag = 1;
+		dt->ut_go = 0;
+	}
+
+	bm0edge = 0;
+	bm3edge = 0;
+	if(BM_SYNC)
+		dt->tbm |= 020;	// shifted to 010 (TBM0) now
+	if(BM_SPACE || BM_SYNC){
+		dt->tbm >>= 1;
+		if(TBM0)
+			bm0edge = 1;
+		else if(TBM3)
+			bm3edge = 1;
+	}
+
+	data1edge = 0;	// goes up before rev checksum is expected
+	data7edge = 0;	// goes up when checksum is seen
+	if(DATA_SYNC)
+		dt->tdata |= 0400;	// shifted to 0200 now
+	if(FWD_DATA_END || REV_DATA_END || DATA_SYNC){
+		dt->tdata >>= 1;
+		if(dt->tdata == 0100)
+			data1edge = 1;
+		else if(dt->tdata == 1)
+			data7edge = 1;
+	}
+
+	if(data1edge)
+		dt->lb = 0;
+
+	// TODO: not sure about rw_active
+	if(data7edge && dt->rw_state == RW_ACTIVE)
+		if(dt->lb != 077)
+printf("UT INFO ERROR\n"),
+			dt->ut_info_error = 1;
+
+	// before active is set below
+	if(dt->rw_state == RW_ACTIVE)
+		dt->tct = !dt->tct;
+
+	// manual mentions tdata6(0) going to 0???
+	if(dt->rw_state == RW_ACTIVE){
+		if(data7edge && RW_DATA_STOP ||
+		   RW_BM_DONE){
+printf("FINISHING JOB\n");
+			dt->ut_jb_done_flag = 1;
+			dt->rw_state = RW_NULL;
+		}
+		if(UTE_ACTIVE_ERROR)
+			dt->rw_state = RW_NULL;
+		if(data7edge && RW_DATA_CONT)
+			dt->rw_state = RW_RQ;
+	}else if(dt->rw_state == RW_RQ){
+		if(UT_BM && bm3edge ||
+		   UT_DATA && data1edge ||
+		   UT_ALL && bm0edge)
+			dt->rw_state = RW_ACTIVE;
+	}
+
+/* TP3 */
+
+	if(RW_ODD)
+		dt->rwb = 0;
+
+	if(TBM3 && BM_SPACE)
+		dt->utek = 040;
+	if(BM_SYNC)
+		dt->uteck = 0;
+	if(TBM3 && !BM_SPACE)
+		dt->uteck = 1;
+
+/* TP4 */
+
+	if(UT_WRITE && RW_ODD){
+		/* Take checksum data from LB */
+		if(UT_DATA && dt->tdata & 0102)
+			dt->rwb = dt->lb;
+		else{
+			dt->rwb |= dctk(dt->dc, DEVNO, dt->ut_rev);
+			if(UTE_DC_DISCONNECT)
+				dt->ut_incomp_block = 1;
+		}
+		if(dt->ut_rev)
+			dt->rwb = dt->rwb>>3 & 07 | dt->rwb<<3 & 070;
+	}
+	if(dt->rw_state == RW_ACTIVE)
+		dt->ut_wren = 0;
+
+//**/				printf("\n");
+
+	dxmove(dt->seldx);
+
+	recalc_dt_req(dt);
+}
+
+static void
+wake_dt(void *dev)
+{
+	Dt551 *dt;
+	IOBus *bus;
+
+	dt = (Dt551*)dev;
+	bus = dt->bus;
+	if(IOB_RESET){
+		dt->ut_incomp_block = 0;
+
+		dt->ut_pia = 0;
+		dt->ut_units = 0;
+		dt->ut_units_select = 0;
+		dt->ut_fcn = 0;
+		dt->ut_time = 0;
+		dt->ut_wren = 0;
+		dt->ut_go = 0;
+		dt->ut_rev = 0;
+		dt->ut_tape_end_flag = 0;
+		dt->ut_tape_end_enable = 0;
+		dt->ut_jb_done_flag = 0;
+		dt->ut_jb_done_enable = 0;
+		dt->time_enable = 0;
+		dt->time_flag = 0;
+		dt->ut_illegal_op = 0;
+		dt->ut_info_error = 0;
+
+		dt->tmk = 0;
+		dt->rwb = 0;
+		dt->tbm = 0;
+		dt->tdata = 0;
+		dt->utek = 0;
+		dt->uteck = 0;
+
+		dt->rw_state = RW_NULL;
+	}
+
+	if(bus->devcode == UTS){
+		if(IOB_STATUS){
+//printf("UTS STATUS\n");
+			// we have no delays (yet?) F25
+			if(dt->rw_state == RW_RQ) bus->c12 |= F26;
+			if(dt->rw_state == RW_ACTIVE) bus->c12 |= F27;
+			if(dt->rw_state == RW_NULL) bus->c12 |= F28;
+			if(dt->ut_incomp_block) bus->c12 |= F29;
+			if(dt->ut_wren) bus->c12 |= F30;
+			if(dt->time_flag) bus->c12 |= F31;
+			if(dt->ut_info_error) bus->c12 |= F32;
+			if(dt->ut_illegal_op) bus->c12 |= F33;
+			if(dt->ut_tape_end_flag) bus->c12 |= F34;
+			if(dt->ut_jb_done_flag) bus->c12 |= F35;
+		}
+	}
+	if(bus->devcode == UTC){
+		if(IOB_STATUS){
+//printf("UTC STATUS\n");
+			if(dt->ut_units_select) bus->c12 |= F19;
+			if(dt->ut_tape_end_enable) bus->c12 |= F20;
+			if(dt->ut_jb_done_enable) bus->c12 |= F21;
+			if(dt->ut_go) bus->c12 |= F22;
+			if(dt->ut_rev) bus->c12 |= F23;
+			if(dt->time_enable) bus->c12 |= F24;
+			bus->c12 |= (dt->ut_time & 03) << 9;
+			bus->c12 |= (dt->ut_fcn & 07) << 6;
+			bus->c12 |= (dt->ut_units & 07) << 3;
+			bus->c12 |= dt->ut_pia & 07;
+		}
+		if(IOB_CONO_CLEAR){
+//printf("UTC CONO CLEAR\n");
+			dt->ut_incomp_block = 0;
+			dt->ut_wren = 0;
+			dt->time_flag = 0;
+			dt->ut_info_error = 0;
+			dt->ut_illegal_op = 0;
+			dt->ut_tape_end_flag = 0;
+			dt->ut_jb_done_flag = 0;
+
+			dt->rw_state = RW_NULL;
+		}
+		if(IOB_CONO_SET){
+//printf("UTC CONO SET\n");
+			int i, n, nunits;
+
+			dt->ut_pia = bus->c12 & 07;
+			dt->ut_units = bus->c12>>3 & 07;
+			dt->ut_fcn = bus->c12>>6 & 07;
+			dt->ut_time = bus->c12>>9 & 03;
+			dt->time_enable = bus->c12>>11 & 1;
+			dt->ut_rev = bus->c12>>12 & 1;
+			dt->ut_go = bus->c12>>13 & 1;
+			dt->ut_jb_done_enable = bus->c12>>14 & 1;
+			dt->ut_tape_end_enable = bus->c12>>15 & 1;
+			dt->ut_units_select = bus->c12>>16 & 1;
+
+			// UT CONO SET LONG
+			//  triggers UT START level until end of delay
+
+			// find selected transport unit
+			n = dt->ut_units == 0 ? 8 : dt->ut_units;
+			dt->seldx = nil;
+			nunits = 0;
+			if(dt->ut_units_select)
+				for(i = 0; i < 8; i++)
+					if(dt->dx[i] && dt->dx[i]->unit == n){
+						dt->seldx = dt->dx[i];
+						nunits++;
+					}
+			if(dt->ut_time){
+				// wait delay
+				dt->time_flag = 1;
+				dt->uteck = 0;
+
+				if(nunits != 1){
+					dt->ut_go = 0;
+					dt->ut_illegal_op = 1;
+					goto ret;
+				}
+				if(dt->ut_btm_switch != UT_WRTM)
+					dt->ut_illegal_op = 1;
+			}
+
+			if(!UT_DN){
+				if(UT_WRTM)
+					dt->rw_state = RW_ACTIVE;
+				else
+					dt->rw_state = RW_RQ;
+			}
+		}
+	}
+ret:
+	recalc_dt_req(dt);
+}
+
+static void
+dtioconnect(Device *dev, IOBus *bus)
+{
+	Dt551 *dt;
+	dt = (Dt551*)dev;
+	dt->bus = bus;
+	bus->dev[UTC] = (Busdev){ dt, wake_dt, 0 };
+	bus->dev[UTS] = (Busdev){ dt, wake_dt, 0 };
+}
+
+/* Connect a dt control to a data control */
+void
+dtconn(Dc136 *dc, Dt551 *dt)
+{
+	dt->dc = dc;
+	dc->devp[DEVNO] = dt;
+}
+
+Device*
+makedt(int argc, char *argv[])
+{
+	Dt551 *dt;
+	Thread th;
+
+	dt = malloc(sizeof(Dt551));
+	memset(dt, 0, sizeof(Dt551));
+
+	dt->dev.type = dt_ident;
+	dt->dev.name = "";
+	dt->dev.attach = nil;
+	dt->dev.ioconnect = dtioconnect;
+
+	// should have 30000 cycles per second
+	th = (Thread){ nil, dtcycle, dt, 1000, 0 };
+	addthread(th);
+
+	return &dt->dev;
+}
diff --git a/emu/init.ini b/emu/init.ini
index a54bdea..1fa53d2 100644
--- a/emu/init.ini
+++ b/emu/init.ini
@@ -4,16 +4,21 @@ mkdev tty tty626
 mkdev ptr ptr760
 mkdev ptp ptp761
 mkdev dc dc136
+mkdev dt0 dt551
+mkdev dx0 dx555
 mkdev fmem fmem162 0
 mkdev cmem0 cmem161C mem_0
 mkdev cmem1 cmem161C mem_1
 mkdev cmem2 cmem161C mem_2
 mkdev cmem3 cmem161C mem_3
 
+devconnect dc dt0
+devconnect dt0 dx0 8
 ioconnect tty apr
 ioconnect ptr apr
 ioconnect ptp apr
 ioconnect dc apr
+ioconnect dt0 apr
 memconnect fmem 0 apr -1
 memconnect cmem0 0 apr 0
 memconnect cmem1 0 apr 1
@@ -23,3 +28,4 @@ memconnect cmem3 0 apr 3
 attach tty /tmp/6tty
 attach ptr ../code/test.rim
 attach ptp ../code/ptp.out
+attach dx0 ../test/out.dt6
diff --git a/emu/main.c b/emu/main.c
index 1295599..70c8cac 100644
--- a/emu/main.c
+++ b/emu/main.c
@@ -597,7 +597,7 @@ getdevice(const char *name)
 }
 
 void
-printdevices(void)
+showdevices(void)
 {
 	Device *dev;
 	for(dev = devlist; dev; dev = dev->next)
@@ -762,8 +762,6 @@ main(int argc, char *argv[])
 	ptr = (Ptr*)getdevice("ptr");
 	ptp = (Ptp*)getdevice("ptp");
 
-	printdevices();
-
 	pthread_create(&sim_thread, nil, simthread, apr);
 	pthread_create(&cmd_thread, nil, cmdthread, nil);
 
diff --git a/emu/mem.c b/emu/mem.c
index e88058d..7063040 100644
--- a/emu/mem.c
+++ b/emu/mem.c
@@ -242,8 +242,7 @@ makecoremem(const char *file)
 
 	core = malloc(sizeof(CMem));
 	memset(core, 0, sizeof(CMem));
-	core->filename = file;
-
+	core->filename = strdup(file);
 	mem = malloc(sizeof(Mem));
 	mem->dev.type = cmem_ident;
 	mem->dev.name = "";
diff --git a/emu/mem_0 b/emu/mem_0
new file mode 100644
index 0000000..3083bc9
--- /dev/null
+++ b/emu/mem_0
@@ -0,0 +1,24 @@
+720200004010
+721200220300
+200740000012
+720340001000
+254000000003
+720000000017
+254000000010
+254000000003
+720200000000
+254200000300
+777600000277
+0
+0
+0
+0
+0
+710600000060
+710740000010
+254000000021
+710440000026
+710740000010
+254000000024
+0
+254000000021
diff --git a/emu/pdp6.h b/emu/pdp6.h
index cd3fbf6..77f15fe 100644
--- a/emu/pdp6.h
+++ b/emu/pdp6.h
@@ -90,7 +90,6 @@ struct Thread
 extern Thread *threads;
 void addthread(Thread th);
 
-/* not used yet */
 typedef struct Device Device;
 struct Device
 {
@@ -106,6 +105,7 @@ struct Device
 extern Device *devlist;
 void adddevice(Device *dev);
 Device *getdevice(const char *name);
+void showdevices(void);
 
 
 /*
@@ -493,5 +493,98 @@ struct Dc136
 #define DC_IDENT "dc136"
 extern char *dc_ident;
 Device *makedc(int argc, char *argv[]);
-void dcgv(Dc136 *dc, word c, int n, int rev);
+void dcgv(Dc136 *dc, int n, word c, int rev);
 word dctk(Dc136 *dc, int n, int rev);
+
+/* Microtape/DECtape */
+
+/* 555 has:
+ *  move tape fwd, rev, auto
+ *  unit selection (1-8)
+ *  motor off, write lock on/off
+*/
+
+typedef struct Dx555 Dx555;
+typedef struct Dt551 Dt551;
+
+/* Transport 555,
+ * a half of it really */
+struct Dx555
+{
+	Device dev;
+
+	Dt551 *dt;
+
+	int unit;
+	int wrlock;
+
+	int fd;
+	uchar *start;
+	uchar *cur;
+	uchar *end;
+};
+#define DX_IDENT "dx555"
+extern char *dx_ident;
+Device *makedx(int argc, char *argv[]);
+void dxconn(Dt551 *dt, Dx555 *dx, int n);
+/*
+void dxatt(Dx555 *dx, uchar *buf, int size);
+void dxff(Dx555 *dx);
+void dxrew(Dx555 *dx);
+*/
+
+/* Control 551 */
+#define UTC (0210>>2)
+#define UTS (0214>>2)
+struct Dt551
+{
+	Device dev;
+	IOBus *bus;
+
+	Dc136 *dc;
+	Dx555 *dx[8];
+	Dx555 *seldx;
+
+	/* enable time and mark track writing */
+	int ut_btm_switch;
+
+	int ut_pia;
+	int ut_units;
+	int ut_units_select;
+	int ut_fcn;
+	int ut_time;
+	int ut_wren;
+	int ut_go;
+	int ut_rev;
+	int ut_tape_end_flag;
+	int ut_tape_end_enable;
+	int ut_jb_done_flag;
+	int ut_jb_done_enable;
+	int time_enable;
+	int time_flag;
+	int ut_illegal_op;
+	int ut_info_error;
+	int ut_incomp_block;
+
+	int tmk;	/* 9 bits */
+	int rwb;	/* 6 bits */
+	int lb;		/* 6 bits */
+	int tbm;	/* 4 bits */
+	int tdata;	/* 8 bits */
+	int tct;	/* 1 bit  */
+	int utek;	/* 6 bits */
+	int uteck;
+
+	int rw_state;	/* null, rq, active */
+
+
+//	int req;
+};
+#define DT_IDENT "dt551"
+extern char *dt_ident;
+Device *makedt(int argc, char *argv[]);
+void dtconn(Dc136 *dc, Dt551 *dt);
+/*
+void dtcono(Dt551 *dt, word iob);
+void dtcycle(Dt551 *dt);
+*/
diff --git a/misc/mkpty.c b/misc/mkpty.c
index 4cc1281..7c98239 100644
--- a/misc/mkpty.c
+++ b/misc/mkpty.c
@@ -37,6 +37,7 @@ reset(int fd)
 #define BAUD 30
 
 struct timespec slp = { 0, 1000*1000*1000 / BAUD };
+struct timespec hupslp = { 0, 100*1000*1000 };
 
 //#define SLEEP nanosleep(&slp, NULL)
 #define SLEEP
@@ -60,6 +61,8 @@ readwrite(int ttyin, int ttyout, int ptyin, int ptyout)
 		}
 		if(n == 0)
 			return;
+		if(pfd[0].revents & POLLHUP)
+			nanosleep(&hupslp, NULL);
 		/* read from pty, write to tty */
 		if(pfd[0].revents & POLLIN){
 			if(n = read(ptyin, &c, 1), n <= 0)
diff --git a/tools/ld6.c b/tools/ld6.c
index 9ebb390..7ad5609 100644
--- a/tools/ld6.c
+++ b/tools/ld6.c
@@ -179,9 +179,13 @@ fixadd(void)
 			continue;
 		}
 		if(a->l)
-			mem[a->addr] += fw(right(s[1]), 0);
+			mem[a->addr] = fw(
+				left(mem[a->addr]) + right(s[1]),
+				right(mem[a->addr]));
 		else
-			mem[a->addr] += fw(0, right(s[1]));
+			mem[a->addr] = fw(
+				left(mem[a->addr]),
+				right(mem[a->addr]) + right(s[1]));
 	}
 }
 
@@ -299,9 +303,13 @@ readblock(int doreloc)
 		reloc <<= 2;
 		if(doreloc){
 			if(bits & 1)
-				block[i] += fw(0, rel);
+				block[i] = fw(
+					left(block[i]),
+					right(block[i]) + rel);
 			if(bits & 2)
-				block[i] += fw(rel, 0);
+				block[i] = fw(
+					left(block[i]) + rel,
+					right(block[i]));
 		}
 	}
 }
@@ -570,7 +578,7 @@ main(int argc, char *argv[])
 	}
 	fixadd();
 
-//	dumpsym();
+	dumpsym();
 
 	checkundef();
 	if(error)