diff --git a/I1620/i1620_cd.c b/I1620/i1620_cd.c
index 3faa69dc..5d93dcf7 100644
--- a/I1620/i1620_cd.c
+++ b/I1620/i1620_cd.c
@@ -1,6 +1,6 @@
 /* i1620_cd.c: IBM 1622 card reader/punch
 
-   Copyright (c) 2002-2012, Robert M. Supnik
+   Copyright (c) 2002-2013, Robert M. Supnik
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
@@ -26,6 +26,8 @@
    cdr          1622 card reader
    cdp          1622 card punch
 
+   10-Dec-13    RMS     Fixed WA card punch translations (Bob Armstrong)
+                        Fixed card reader EOL processing (Bob Armstrong)
    19-Mar-12    RMS     Fixed declarations of saved_pc, io_stop (Mark Pizzolato)
    19-Jan-07    RMS     Set UNIT_TEXT flag
    13-Jul-06    RMS     Fixed card reader fgets call (Tom McBride)
@@ -112,7 +114,7 @@ DEVICE cdp_dev = {
 */
 /* Card reader (ASCII) to numeric (one digit) */
 
-const char cdr_to_num[128] = {
+const int8 cdr_to_num[128] = {
  0x00,   -1,   -1,   -1,   -1,   -1,   -1,   -1,        /* 00 */
    -1, 0x00, 0x00,   -1,   -1, 0x00,   -1,   -1,
    -1,   -1,   -1,   -1,   -1,   -1,   -1,   -1,        /* 10 */
@@ -184,11 +186,21 @@ const int8 cdr_to_alp[128] = {
    There is no way to punch 0-5-8 (~), 0-6-8 (\),
    11-5-8 (]), 11-6-8 (;), 11-7-8 (_),
    12-5-8 ([), or 12-6-8 (<)
+
+According to Bob Armstrong,
+   the FORTRAN compiler is sneaky and actually punches numeric
+   data (i.e. data that it knows will be read back using RNCD)
+   in alphameric mode with WACD. Because of that there are some
+   alpha to ASCII translations that absolutely MUST work out right
+   or otherwise we won't be able to load FORTRAN object decks.
+
+     50 - must "punch" as ] (flagged zero) (used to be "_")
+     0A - must "punch" as | (record mark)  (used to be "'")
 */
 
 const int8 alp_to_cdp[256] = {
  ' ',  -1, '?', '.', ')',  -1,  -1, '}',                /* 00 */
-  -1,  -1, '\'', -1,  -1,  -1,  -1, '"',
+  -1,  -1, '|', -1,  -1,  -1,  -1, '"',
  '+',  -1, '!', '$', '*', ']',  -1,  -1,                /* 10 */ 
   -1,  -1,  -1,  -1,  -1,  -1,  -1,  -1,
  '-', '/', '|', ',', '(',  -1,  -1,  -1,                /* 20 */
@@ -197,7 +209,7 @@ const int8 alp_to_cdp[256] = {
   -1,  -1, '|',  -1,  -1,  -1,  -1, '"',
   -1, 'A', 'B', 'C', 'D', 'E', 'F', 'G',                /* 40 */
  'H', 'I',  -1,  -1,  -1,  -1,  -1,  -1,
- '_', 'J', 'K', 'L', 'M', 'N', 'O', 'P',                /* 50 */
+ ']', 'J', 'K', 'L', 'M', 'N', 'O', 'P',                /* 50 */
  'Q', 'R', '?', '=',  -1,  -1,  -1, '}',
   -1, '/', 'S', 'T', 'U', 'V', 'W', 'X',                /* 60 */
  'Y', 'Z', '|', ',',  -1,  -1,  -1,  -1,
@@ -279,7 +291,12 @@ switch (op) {                                           /* case on op */
 return sta;
 }
 
-/* Fill card reader buffer - all errors are hard errors */
+/* Fill card reader buffer - all errors are hard errors
+
+   As Bob Armstrong pointed out, this routines needs to account
+   for variants in text file formats, which may terminate lines
+   with cr-lf (Windows), lf (UNIX), or cr (Mac).
+*/
 
 t_stat cdr_read (void)
 {
@@ -302,6 +319,22 @@ if (ferror (cdr_unit.fileref)) {                        /* error? */
     clearerr (cdr_unit.fileref);
     return SCPE_IOERR;
     }
+if ((i = strlen (cdr_buf)) > 0) {                       /* anything at all? */
+    if (cdr_buf[i-1] == '\n') {                         /* line end in \n? */
+        cdr_buf[i-1] = 0;                               /* remove it */
+        }
+    else if (cdr_buf[i-1] == '\r') {                    /* line end in \r? */
+        cdr_buf[i-1] = 0;                               /* remove it */
+        cdr_unit.pos = ftell (cdr_unit.fileref);        /* save position */
+        if (fgetc (cdr_unit.fileref) != '\n')           /* next char not \n? */
+            fseek (cdr_unit.fileref, cdr_unit.pos, SEEK_SET); /* then rewind */  
+        }
+    else {                                              /* line too long */
+        ind[IN_RDCHK] = 1;
+        perror ("CDR line too long");
+        return SCPE_IOERR;
+        }
+    }
 cdr_unit.pos = ftell (cdr_unit.fileref);                /* update position */
 getc (cdr_unit.fileref);                                /* see if more */
 if (feof (cdr_unit.fileref))                            /* eof? set last */
@@ -362,7 +395,7 @@ uint8 z, d;
 switch (op) {                                           /* decode op */
 
     case OP_DN:
-        return cdp_num (pa, 20000 - (pa % 20000), TRUE); /* dump numeric */
+        return cdp_num (pa, 20000 - (pa % 20000), TRUE);/* dump numeric */
 
     case OP_WN:
         return cdp_num (pa, CD_LEN, FALSE);             /* write numeric */
@@ -404,7 +437,8 @@ while (ncd-- >= 0) {                                    /* until done */
         break;
     for (i = 0; i < len; i++) {                         /* one card */
         d = M[pa] & (FLAG | DIGIT);                     /* get char */
-        if (dump && (d == FLAG)) cdc = '-';             /* dump? F+0 is diff */
+        if (dump && (d == FLAG))                        /* dump? F+0 is diff */
+            cdc = '-';
         else cdc = num_to_cdp[d];                       /* translate */
         if (cdc < 0) {                                  /* bad char? */
             ind[IN_WRCHK] = 1;                          /* set write check */
diff --git a/I1620/i1620_cpu.c b/I1620/i1620_cpu.c
index 5ef99843..343ddc02 100644
--- a/I1620/i1620_cpu.c
+++ b/I1620/i1620_cpu.c
@@ -1,6 +1,6 @@
 /* i1620_cpu.c: IBM 1620 CPU simulator
 
-   Copyright (c) 2002-2008, Robert M. Supnik
+   Copyright (c) 2002-2013, Robert M. Supnik
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
@@ -26,7 +26,9 @@
    This CPU module incorporates code and comments from the 1620 simulator by
    Geoff Kuenning, with his permission.
 
-   28-May-06    RMS     Fixed bug in cpu history Peter Schorn)
+   10-Dec-13    RMS     Fixed several bugs in add and compare (Bob Armstrong)
+                        Fixed handling of P field in K instruction (Bob Armstrong)
+   28-May-06    RMS     Fixed bug in cpu history (Peter Schorn)
    22-Sep-05    RMS     Fixed declarations (Sterling Garwood)
    16-Aug-05    RMS     Fixed C++ declaration and cast problems
    07-Nov-04    RMS     Added instruction history
@@ -291,7 +293,7 @@ const int32 op_table[100] = {
     IF_VPA + IF_VQA,                                    /* TR */
     IF_VPA,                                             /* SF */
     IF_VPA,                                             /* CF */
-    IF_VPA,                                             /* K */
+    0,                                                  /* K */
     IF_VPA,                                             /* DN */
     IF_VPA,                                             /* RN */
     IF_VPA,                                             /* RA */
@@ -384,6 +386,21 @@ t_stat (*iodisp[NUM_IO])(uint32 op, uint32 pa, uint32 f0, uint32 f1) = {
     NULL, NULL, NULL, NULL, NULL
     };
 
+/* K instruction validate P field table */
+
+const uint8 k_valid_p[NUM_IO] = {
+    0, 0, 0, 0, 0, 0, 0, 1, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    };
+
 /* Indicator table: -1 = illegal, +1 = resets when tested */
 
 const int32 ind_table[NUM_IND] = {
@@ -687,11 +704,12 @@ while (reason == 0) {                                   /* loop until halted */
             reason = STOP_OVERFL;
         break;
 
+/* IBM's diagnostics try a compare that generates a carry out; it does not
+   generate overflow. Therefore, do not set overflow on a carry out status. */
+
     case OP_C:
     case OP_CM:
         reason = add_field (PAR, QAR, TRUE, FALSE, 0, &sta); /* sub, nostore */
-        if (sta == ADD_CARRY)                           /* cout => ovflo */
-            ind[IN_OVF] = 1;
         if (ar_stop && ind[IN_OVF])
             reason = STOP_OVERFL;
         break;
@@ -703,7 +721,7 @@ while (reason == 0) {                                   /* loop until halted */
         reason = mul_field (PAR, QAR);                  /* multiply */
         break;
 
-/* IO instructions - P is valid */
+/* IO instructions - P is valid, except for K */
 
     case OP_RA:
     case OP_WA:
@@ -711,7 +729,6 @@ while (reason == 0) {                                   /* loop until halted */
             reason = STOP_INVEAD;                       /* stop */
             break;
             }
-    case OP_K:
     case OP_DN:
     case OP_RN:
     case OP_WN:
@@ -723,6 +740,21 @@ while (reason == 0) {                                   /* loop until halted */
         else reason = iodisp[dev] (op, PAR, f0, f1);    /* call device */
         break;
 
+    case OP_K:
+        dev = get_2d (ADDR_A (saved_PC, I_IO));         /* get IO dev */
+        if (k_valid_p[dev]) {                          /* validate P? */
+            reason = get_addr (pla, 5, TRUE, &PAR);     /* get P addr */
+            if (reason != SCPE_OK)                      /* stop if error */
+                 break;
+            }
+        else PAR = 0;
+        f0 = M[ADDR_A (saved_PC, I_CTL)] & DIGIT;       /* get function */
+        f1 = M[ADDR_A (saved_PC, I_CTL + 1)] & DIGIT;
+        if ((dev < 0) || (iodisp[dev] == NULL))         /* undefined dev? */
+            reason = STOP_INVIO;                        /* stop */
+        else reason = iodisp[dev] (op, PAR, f0, f1);    /* call device */
+        break;
+
 /* Divide special feature instructions */
 
     case OP_LD:
@@ -1296,7 +1328,8 @@ return SCPE_OK;
 
    Reference Manual: "When the sum is zero, the sign of the P field
    is retained."
-*/
+
+   Bob Armstrong: record marks are treated by add as though they were zero */
 
 t_stat add_field (uint32 d, uint32 s, t_bool sub, t_bool sto, uint32 skp, int32 *sta)
 {
@@ -1312,6 +1345,10 @@ ind[IN_EZ] = 1;                                         /* assume zero */
 
 dst = M[d] & DIGIT;                                     /* 1st digits */
 src = M[s] & DIGIT;
+if (dst == REC_MARK)                                    /* chk for rec mark */
+    dst = 0;
+if (src == REC_MARK)
+    src = 0;
 if (BAD_DIGIT (dst) || BAD_DIGIT (src))                 /* bad digit? */
      return STOP_INVDIG;
 if (comp)                                               /* complement? */
@@ -1322,11 +1359,15 @@ if (sto)                                                /* store */
 MM (d); MM (s);                                         /* decr mem addrs */
 do {
     dst = M[d] & DIGIT;                                 /* get dst digit */
+    if (dst == REC_MARK)
+        dst = 0;
     dst_f = M[d] & FLAG;                                /* get dst flag */
     if (src_f)                                          /* src done? src = 0 */
         src = 0;
     else {
         src = M[s] & DIGIT;                             /* get src digit */
+        if (src == REC_MARK)
+            src = 0;
         if (cnt >= skp)                                 /* get src flag */
             src_f = M[s] & FLAG;
         MM (s);                                         /* decr src addr */
@@ -1344,12 +1385,18 @@ do {
     } while (dst_f == 0);                               /* until dst done */
 if (!src_f)                                             /* !src done? ovf */
     ind[IN_OVF] = 1;
+
+/* Because recomplement is done (model 1) with table lookup, the first digit
+   must be explicitly 10s complemented, and not 9s complemented with a carry
+   in of 1. (Bob Armstrong) */
+
 if (comp && !cry && !ind[IN_EZ]) {                      /* recomp needed? */
     ind[IN_HP] = ind[IN_HP] ^ 1;                        /* flip indicator */
     if (sto) {                                          /* storing? */
-        for (cry = 1, dp = dsv; dp != d; ) {            /* rescan */
+        for (cry = 0, dp = dsv; dp != d; ) {            /* rescan */
             dst = M[dp] & DIGIT;                        /* get dst digit */
-            res = add_one_digit (9 - dst, 0, &cry);     /* "add" */
+            dst = (dp == dsv)? (10 - dst): (9 - dst);	/* 10 or 9s comp */
+            res = add_one_digit (0, dst, &cry);         /* "add" */
             M[dp] = (M[dp] & FLAG) | res;               /* store */
             MM (dp);                                    /* decr dst addr */
             }
@@ -1371,7 +1418,8 @@ uint32 add_one_digit (uint32 dst, uint32 src, uint32 *cry)
 {
 uint32 res;
 
-if (*cry) src = src + 1;                                /* cry in? incr src */
+if (*cry)                                               /* cry in? incr src */
+    src = src + 1;
 if (src >= 10) {                                        /* src > 10? */
     src = src - 10;                                     /* src -= 10 */
     *cry = 1;                                           /* carry out */
diff --git a/I1620/i1620_lp.c b/I1620/i1620_lp.c
index 4254bf09..147b8e8e 100644
--- a/I1620/i1620_lp.c
+++ b/I1620/i1620_lp.c
@@ -1,6 +1,6 @@
 /* i1620_lp.c: IBM 1443 line printer simulator
 
-   Copyright (c) 2002-2008, Robert M. Supnik
+   Copyright (c) 2002-2013, Robert M. Supnik
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
@@ -25,6 +25,8 @@
 
    lpt          1443 line printer
 
+   10-Dec-13    RMS     Fixed DN wraparound (Bob Armstrong)
+                        Fixed test on VFU 10 (Bob Armstrong)
    19-Jan-07    RMS     Added UNIT_TEXT flag
    21-Sep-05    RMS     Revised translation tables for 7094/1401 compatibility
    29-Dec-03    RMS     Fixed bug in scheduling
@@ -56,7 +58,7 @@ t_stat lpt_svc (UNIT *uptr);
 t_stat lpt_reset (DEVICE *dptr);
 t_stat lpt_attach (UNIT *uptr, char *cptr);
 void lpt_buf_init (void);
-t_stat lpt_num (uint32 pa, uint32 len, uint32 f1);
+t_stat lpt_num (uint32 pa, uint32 len, uint32 f1, t_bool dump);
 t_stat lpt_print (void);
 t_stat lpt_space (int32 lines, int32 lflag);
 
@@ -169,10 +171,10 @@ switch (op) {                                           /* decode op */
         break;
 
     case OP_DN:
-        return lpt_num (pa, 20000 - (pa % 20000), f1);  /* dump numeric */
+        return lpt_num (pa, 20000 - (pa % 20000), f1, TRUE);  /* dump numeric */
 
     case OP_WN:
-        return lpt_num (pa, 0, f1);                     /* write numeric */
+        return lpt_num (pa, 0, f1, FALSE);              /* write numeric */
 
     case OP_WA:
         for ( ; lpt_bptr < LPT_BSIZE; lpt_bptr++) {     /* only fill buf */
@@ -205,18 +207,16 @@ return SCPE_OK;
 
 /* Print numeric */
 
-t_stat lpt_num (uint32 pa, uint32 len, uint32 f1)
+t_stat lpt_num (uint32 pa, uint32 len, uint32 f1, t_bool dump)
 {
-uint32 end;
 uint8 d;
 int8 lpc;
 t_stat r, sta;
 
 sta = SCPE_OK;
-end = pa + len;
 for ( ; lpt_bptr < LPT_BSIZE; lpt_bptr++) {             /* only fill buf */
     d = M[pa];                                          /* get digit */
-    if (len? (pa >= end):                               /* end reached? */
+    if (dump? (len-- == 0):                             /* end reached? */
         ((d & REC_MARK) == REC_MARK))
         break;
     lpc = num_to_lpt[d];                                /* translate */
@@ -270,7 +270,7 @@ lpt_savctrl = 0x61;                                     /* reset ctrl */
 if ((ctrl & K_LIN) == ((ctrl & K_IMM)? 0: K_LIN))       /* space lines? */
     return lpt_space (ctrl & K_LCNT, FALSE);
 chan = lpt_savctrl & K_CHAN;                            /* basic chan */
-if (lpt_savctrl & K_CH10) {                             /* chan 10-12? */
+if ((lpt_savctrl & K_CH10) == 0) {                      /* chan 10-12? */
     if (chan == 0)
         chan = 10;
     else if (chan == 3)
diff --git a/I1620/i1620_pt.c b/I1620/i1620_pt.c
index 88323ade..a16dacfd 100644
--- a/I1620/i1620_pt.c
+++ b/I1620/i1620_pt.c
@@ -1,6 +1,6 @@
 /* i1620_pt.c: IBM 1621/1624 paper tape reader/punch simulator
 
-   Copyright (c) 2002-2012, Robert M Supnik
+   Copyright (c) 2002-2013, Robert M Supnik
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
@@ -26,6 +26,8 @@
    ptr          1621 paper tape reader
    ptp          1624 paper tape punch
 
+   21-Dec-13    RMS     Fixed translation of paper tape code X0C
+   10-Dec-13    RMS     Fixed DN wraparound (Bob Armstrong)
    19-Mar-12    RMS     Fixed declaration of io_stop (Mark Pizzolato)
    21-Sep-05    RMS     Revised translation tables for 7094/1401 compatibility
    25-Apr-03    RMS     Revised for extended file support
@@ -49,7 +51,7 @@ t_stat ptr_boot (int32 unitno, DEVICE *dptr);
 t_stat ptr_read (uint8 *c, t_bool ignfeed);
 t_stat ptp_reset (DEVICE *dptr);
 t_stat ptp_write (uint32 c);
-t_stat ptp_num (uint32 pa, uint32 len);
+t_stat ptp_num (uint32 pa, uint32 len, t_bool dump);
 
 /* PTR data structures
 
@@ -129,7 +131,7 @@ const int8 ptr_to_num[128] = {
  0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x10, 0x1E, 0x1F,
  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,        /* XO */
  0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x00, 0x0E, 0x0F,
- 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,        /* XOC */
+ 0x10, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,        /* XOC */
  0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x00, 0x0E, 0x0F
  };
 
@@ -212,7 +214,7 @@ const int8 alp_to_ptp[256] = {
 
 t_stat ptr (uint32 op, uint32 pa, uint32 f0, uint32 f1)
 {
-uint32 i;
+uint32 i, q = 0;
 int8 mc;
 uint8 ptc;
 t_stat r, sta;
@@ -229,6 +231,8 @@ switch (op) {                                           /* case on op */
                 M[pa] = REC_MARK;                       /* store rec mark */
                 return sta;                             /* done */
                 }
+            if (pa == 18976)
+                q++;
             if (bad_par[ptc]) {                         /* bad parity? */
                 ind[IN_RDCHK] = 1;                      /* set read check */
                 if (io_stop)                            /* set return status */
@@ -389,10 +393,10 @@ t_stat r;
 switch (op) {                                           /* decode op */
 
     case OP_DN:
-        return ptp_num (pa, 20000 - (pa % 20000));      /* dump numeric */
+        return ptp_num (pa, 20000 - (pa % 20000), TRUE);/* dump numeric */
 
     case OP_WN:
-        return ptp_num (pa, 0);                         /* punch numeric */
+        return ptp_num (pa, 0, FALSE);                  /* punch numeric */
 
     case OP_WA:
         for (i = 0; i < MEMSIZE; i = i + 2) {           /* stop runaway */
@@ -456,16 +460,15 @@ return STOP_RWRAP;
 
 /* Punch tape numeric - cannot generate parity errors */
 
-t_stat ptp_num (uint32 pa, uint32 len)
+t_stat ptp_num (uint32 pa, uint32 len, t_bool dump)
 {
 t_stat r;
 uint8 d;
-uint32 i, end;
+uint32 i;
 
-end = pa + len;
 for (i = 0; i < MEMSIZE; i++) {                         /* stop runaway */
     d = M[pa] & (FLAG | DIGIT);                         /* get char */
-    if (len? (pa >= end):                               /* dump: end reached? */
+    if (dump? (len-- == 0):                             /* dump: end reached? */
        ((d & REC_MARK) == REC_MARK))                    /* write: rec mark? */
         return ptp_write (PT_EL);                       /* end record */
     r = ptp_write (num_to_ptp[d]);                      /* write */
diff --git a/I1620/i1620_sys.c b/I1620/i1620_sys.c
index e9c501b0..c25e9052 100644
--- a/I1620/i1620_sys.c
+++ b/I1620/i1620_sys.c
@@ -394,7 +394,7 @@ if (opcode[i].str == NULL)
 if (I_GETQP (opfl) == I_M_QNP)                          /* Q no print? */
     qmp = 0;
 
-fprintf (of, "%s", opcode[i].str);                            /* print opcode */
+fprintf (of, "%s", opcode[i].str);                      /* print opcode */
 if (I_GETPP (opfl) == I_M_PP)                           /* P required? */
     fprint_addr (of, ' ', &val[I_P], I_M_QX);
 else if ((I_GETPP (opfl) == I_M_PCP) && (pmp || qmp))   /* P opt & needed? */
diff --git a/I1620/i1620_tty.c b/I1620/i1620_tty.c
index ac4a1021..aefa0ba5 100644
--- a/I1620/i1620_tty.c
+++ b/I1620/i1620_tty.c
@@ -1,6 +1,6 @@
 /* i1620_tty.c: IBM 1620 typewriter
 
-   Copyright (c) 2002-2008, Robert M. Supnik
+   Copyright (c) 2002-2014, Robert M. Supnik
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
@@ -25,6 +25,8 @@
 
    tty          console typewriter
 
+   02-Jan-14    RMS     Added variable tab stops
+   10-Dec-13    RMS     Fixed DN wraparound (Bob Armstrong)
    21-Sep-05    RMS     Revised translation tables for 7094/1401 compatibility
    22-Dec-02    RMS     Added break test
 */
@@ -34,6 +36,19 @@
 #define TTO_COLMAX      80
 
 int32 tto_col = 0;
+uint8 tto_tabs[TTO_COLMAX + 1] = {
+ 0,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1,0,0,0,0,0,0,0,
+ 1
+};
 
 extern uint8 M[MAXMEMSIZE];
 extern uint8 ind[NUM_IND];
@@ -44,10 +59,11 @@ void tti_unlock (void);
 t_stat tti_rnum (int8 *c);
 t_stat tti_ralp (int8 *c);
 t_stat tti_read (int8 *c);
-t_stat tto_num (uint32 pa, uint32 len);
+t_stat tto_num (uint32 pa, uint32 len, t_bool dump);
 t_stat tto_write (uint32 c);
 t_stat tty_svc (UNIT *uptr);
 t_stat tty_reset (DEVICE *dptr);
+t_stat tty_set_fixtabs (UNIT *uptr, int32 val, char *cptr, void *desc);
 
 /* TTY data structures
 
@@ -64,8 +80,20 @@ REG tty_reg[] = {
     { NULL }
     };
 
+MTAB tty_mod[] = {
+    { MTAB_XTD|MTAB_VDV, TTO_COLMAX, NULL, "TABS",
+      &sim_tt_settabs, NULL, (void *) tto_tabs },
+    { MTAB_XTD|MTAB_VDV|MTAB_NMO, TTO_COLMAX, "TABS", NULL,
+      NULL, &sim_tt_showtabs, (void *) tto_tabs },
+    { MTAB_XTD|MTAB_VDV, 0, NULL, "NOTABS",
+      &tty_set_fixtabs, NULL, NULL },
+    { MTAB_XTD|MTAB_VDV, 8, NULL, "DEFAULTTABS",
+      &tty_set_fixtabs, NULL, NULL },
+    { 0 }
+    };
+
 DEVICE tty_dev = {
-    "TTY", &tty_unit, tty_reg, NULL,
+    "TTY", &tty_unit, tty_reg, tty_mod,
     1, 10, 31, 1, 8, 7,
     NULL, NULL, &tty_reset,
     NULL, NULL, NULL
@@ -214,10 +242,10 @@ switch (op) {                                           /* case on op */
         break;  
 
     case OP_DN:
-        return tto_num (pa, 20000 - (pa % 20000));      /* dump numeric */
+        return tto_num (pa, 20000 - (pa % 20000), TRUE);/* dump numeric */
 
     case OP_WN:
-        return tto_num (pa, 0);                         /* type numeric */
+        return tto_num (pa, 0, FALSE);                  /* type numeric */
 
     case OP_WA:
         for (i = 0; i < MEMSIZE; i = i + 2) {           /* stop runaway */
@@ -307,16 +335,15 @@ return SCPE_OK;
 
 /* Write numerically - cannot generate parity errors */
 
-t_stat tto_num (uint32 pa, uint32 len)
+t_stat tto_num (uint32 pa, uint32 len, t_bool dump)
 {
 t_stat r;
 uint8 d;
-uint32 i, end;
+uint32 i;
 
-end = pa + len;
 for (i = 0; i < MEMSIZE; i++) {                         /* (stop runaway) */
     d = M[pa];                                          /* get char */
-    if (len? (pa >= end):                               /* dump: end reached? */
+    if (dump? (len-- == 0):                             /* dump: end reached? */
        ((d & REC_MARK) == REC_MARK))                    /* write: rec mark? */
         return SCPE_OK;                                 /* end operation */
     if (d & FLAG)                                       /* flag? */
@@ -336,23 +363,23 @@ t_stat tto_write (uint32 c)
 int32 rpt;
 
 if (c == '\t') {                                        /* tab? */
-    rpt = 8 - (tto_col % 8);                            /* distance to next */
-    tto_col = tto_col + rpt;                            /* tab over */
-    while (rpt-- > 0)                                   /* use spaces */
-        sim_putchar (' ');
-    return SCPE_OK;
+    for (rpt = tto_col + 1;                             /* find tab stop */
+        (tto_tabs[rpt] == 0) && (rpt <= TTO_COLMAX);
+        rpt++) ;
+    for ( ; tto_col < rpt; tto_col++)
+        sim_putchar (' ');                              /* use spaces */
     }
-if (c == '\r') {                                        /* return? */
+else if (c == '\r') {                                   /* return? */
     sim_putchar ('\r');                                 /* crlf */
     sim_putchar ('\n');
     tto_col = 0;                                        /* clear colcnt */
     return SCPE_OK;
     }
-if ((c == '\n') || (c == 007)) {                        /* non-spacing? */
+else if ((c == '\n') || (c == 007)) {                   /* non-spacing? */
     sim_putchar (c);
     return SCPE_OK;
     }
-if (c == '\b')                                          /* backspace? */
+else if (c == '\b')                                     /* backspace? */
     tto_col = tto_col? tto_col - 1: 0;
 else tto_col++;                                         /* normal */
 if (tto_col > TTO_COLMAX) {                             /* line wrap? */
@@ -360,7 +387,8 @@ if (tto_col > TTO_COLMAX) {                             /* line wrap? */
     sim_putchar ('\n');
     tto_col = 0;
     }
-sim_putchar (c);
+if (c != '\t')
+    sim_putchar (c);
 return SCPE_OK;
 }
 
@@ -382,6 +410,7 @@ t_stat tty_reset (DEVICE *dptr)
 {
 sim_activate (&tty_unit, tty_unit.wait);                /* activate poll */
 tto_col = 0;
+tto_tabs[TTO_COLMAX] = 1;                               /* tab stop at limit */
 return SCPE_OK;
 }
 
@@ -392,3 +421,17 @@ void tti_unlock (void)
 tto_write ('>');
 return;
 }
+
+/* Set tab stops at fixed modulus */
+
+t_stat tty_set_fixtabs (UNIT *uptr, int32 val, char *cptr, void *desc)
+{
+int32 i;
+
+for (i = 0; i < TTO_COLMAX; i++) {
+    if ((val != 0) && (i != 0) && ((i % val) == 0))
+        tto_tabs[i] = 1;
+    else tto_tabs[i] = 0;
+    }
+return SCPE_OK;
+}
diff --git a/doc/i1620_doc.doc b/doc/i1620_doc.doc
index bdb40704..cee20c37 100644
Binary files a/doc/i1620_doc.doc and b/doc/i1620_doc.doc differ
diff --git a/sim_console.c b/sim_console.c
index f861ffdc..deff8c36 100644
--- a/sim_console.c
+++ b/sim_console.c
@@ -1,6 +1,6 @@
 /* sim_console.c: simulator console I/O library
 
-   Copyright (c) 1993-2012, Robert M Supnik
+   Copyright (c) 1993-2014, Robert M Supnik
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
@@ -23,6 +23,7 @@
    used in advertising or otherwise to promote the sale, use or other dealings
    in this Software without prior written authorization from Robert M Supnik.
 
+   02-Jan-14    RMS     Added tab stop routines
    18-Mar-12    RMS     Removed unused reference to sim_switches (Dave Bryan)
    07-Dec-11    MP      Added sim_ttisatty to support reasonable behaviour (i.e. 
                         avoid in infinite loop) in the main command input
@@ -75,7 +76,7 @@
    01-Feb-02    RMS     Added VAX fix (Robert Alan Byer)
    19-Sep-01    RMS     More MacOS changes
    31-Aug-01    RMS     Changed int64 to t_int64 for Windoze
-   20-Jul-01    RMS     Added Macintosh support (Louis Chretien, Peter Schorn, Ben Supnik)
+   20-Jul-01    RMS     Added MacOS support (Louis Chretien, Peter Schorn, Ben Supnik)
    15-May-01    RMS     Added logging support
    05-Mar-01    RMS     Added clock calibration support
    08-Dec-00    BKR     Added OS/2 support (Bruce Ray)
@@ -1599,6 +1600,59 @@ else c = c & 0377;
 return c;
 }
 
+/* Tab stop array handling
+
+   *desc points to a uint8 array of length val
+
+   Columns with tabs set are non-zero; columns without tabs are 0 */
+
+t_stat sim_tt_settabs (UNIT *uptr, int32 val, char *cptr, void *desc)
+{
+uint8 *temptabs, *tabs = (uint8 *) desc;
+int32 i, d;
+t_stat r;
+char gbuf[CBUFSIZE];
+
+if ((cptr == NULL) || (tabs == NULL) || (val <= 1))
+    return SCPE_IERR;
+if (*cptr == 0)
+    return SCPE_2FARG;
+if ((temptabs = (uint8 *)malloc (val)) == NULL)
+    return SCPE_MEM;
+for (i = 0; i < val; i++)
+    temptabs[i] = 0;
+do {
+    cptr = get_glyph (cptr, gbuf, ';');
+    d = get_uint (gbuf, 10, val, &r);
+    if ((r != SCPE_OK) || (d == 0)) {
+        free (temptabs);
+        return SCPE_ARG;
+        }
+    temptabs[d - 1] = 1;
+    } while (*cptr != 0);
+for (i = 0; i < val; i++)
+    tabs[i] = temptabs[i];
+free (temptabs);
+return SCPE_OK;
+}
+
+t_stat sim_tt_showtabs (FILE *st, UNIT *uptr, int32 val, void *desc)
+{
+uint8 *tabs = (uint8 *) desc;
+int32 i, any;
+
+if ((st == NULL) || (val == 0) || (desc == NULL))
+    return SCPE_IERR;
+for (i = any = 0; i < val; i++) {
+    if (tabs[i] != 0) {
+        fprintf (st, (any? ";%d": "%d"), i + 1);
+        any = 1;
+        }
+    }
+fprintf (st, (any? "\n": "no tabs set\n"));
+return SCPE_OK;
+}
+
 
 #if defined(SIM_ASYNCH_IO) && defined(SIM_ASYNCH_MUX)
 extern pthread_mutex_t     sim_tmxr_poll_lock;
diff --git a/sim_console.h b/sim_console.h
index f33e31ec..a9d02290 100644
--- a/sim_console.h
+++ b/sim_console.h
@@ -1,6 +1,6 @@
 /* sim_console.h: simulator console I/O library headers
 
-   Copyright (c) 1993-2008, Robert M Supnik
+   Copyright (c) 1993-2014, Robert M Supnik
 
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
@@ -23,6 +23,7 @@
    used in advertising or otherwise to promote the sale, use or other dealings
    in this Software without prior written authorization from Robert M Supnik.
 
+   02-Jan-14    RMS     Added tab stop routines
    17-Jan-11    MP      Added buffered line capabilities
    22-Jun-06    RMS     Implemented SET/SHOW PCHAR
    22-Nov-05    RMS     Added central input/output conversion support
@@ -92,6 +93,8 @@ t_stat sim_ttclose (void);
 t_bool sim_ttisatty (void);
 int32 sim_tt_inpcvt (int32 c, uint32 mode);
 int32 sim_tt_outcvt (int32 c, uint32 mode);
+t_stat sim_tt_settabs (UNIT *uptr, int32 val, char *cptr, void *desc);
+t_stat sim_tt_showtabs (FILE *st, UNIT *uptr, int32 val, void *desc);
 
 extern int32 sim_int_char;                                  /* interrupt character */
 extern int32 sim_brk_char;                                  /* break character */