diff --git a/H316/h316_lp.c b/H316/h316_lp.c
index 230626de..b1da1cc8 100644
--- a/H316/h316_lp.c
+++ b/H316/h316_lp.c
@@ -1,6 +1,6 @@
 /* h316_lp.c: Honeywell 316/516 line printer
 
-   Copyright (c) 1999-2015, Robert M. Supnik
+   Copyright (c) 1999-2021, 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"),
@@ -25,7 +25,8 @@
 
    lpt          line printer
 
-   03-Jul-13    RLA     compatibility changes for extended interrupts
+   09-Jun-21    RMS     Added error detection, removed use of ftell
+   03-Jul-13    RLA     Compatibility changes for extended interrupts
    09-Jun-07    RMS     Fixed lost last print line (Theo Engel)
    19-Jan-06    RMS     Added UNIT_TEXT flag
    03-Apr-06    RMS     Fixed bug in blanks backscanning (Theo Engel)
@@ -321,7 +322,12 @@ if (lpt_svcst & LPT_SVCSH) {                            /* shuttling? */
             }
         lpt_buf[i + 1] = 0;
         fputs (lpt_buf, uptr->fileref);                 /* output buf */
-        uptr->pos = ftell (uptr->fileref);              /* update pos */
+        if (ferror (uptr->fileref)) {                   /* error? */
+            perror ("LPT I/O error");
+            clearerr (uptr->fileref);
+            return SCPE_IOERR;
+            }
+        uptr->pos = uptr->pos + strlen (lpt_buf);       /* update pos */
         for (i = 0; i < LPT_WIDTH; i++)                 /* clear buf */
             lpt_buf[i] = ' ';
         lpt_prdn = 1;                                   /* print done */
@@ -330,7 +336,12 @@ if (lpt_svcst & LPT_SVCSH) {                            /* shuttling? */
 if (lpt_svcst & LPT_SVCPA) {                            /* paper advance */
     SET_INT (INT_LPT);                                  /* interrupt */
     fputs (lpt_cc[lpt_svcch & 03], uptr->fileref);      /* output eol */
-    uptr->pos = ftell (uptr->fileref);                  /* update pos */
+    if (ferror (uptr->fileref)) {                       /* error? */
+        perror ("LPT I/O error");
+        clearerr (uptr->fileref);
+        return SCPE_IOERR;
+        }
+    uptr->pos = uptr->pos + strlen (lpt_cc[lpt_svcch & 03]); /* update pos */
     }
 lpt_svcst = 0;
 return SCPE_OK;
diff --git a/I1401/i1401_cd.c b/I1401/i1401_cd.c
index f20cb17b..e60e93f9 100644
--- a/I1401/i1401_cd.c
+++ b/I1401/i1401_cd.c
@@ -1,6 +1,6 @@
 /* i1401_cd.c: IBM 1402 card reader/punch
 
-   Copyright (c) 1993-2017, Robert M. Supnik
+   Copyright (c) 1993-2021, 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"),
@@ -35,6 +35,7 @@
    Cards are represented as ASCII text streams terminated by newlines.
    This allows cards to be created and edited as normal files.
 
+   09-Jun-21    RMS     Removed use of ftell on output for pipe compatibility
    09-Mar-17    RMS     Protect character conversions from gargage files (COVERITY)
    05-May-16    RMS     Fixed calling sequence inconsistency (Mark Pizzolato)
    28-Feb-15    RMS     Added read from console
@@ -295,13 +296,13 @@ else uptr = &stack_unit[0];                             /* then default */
 if ((uptr->flags & UNIT_ATT) == 0)                      /* attached? */
     return SCPE_OK;
 fputs (cdr_buf, uptr->fileref);                         /* write card */
-uptr->pos = ftell (uptr->fileref);                      /* update position */
 if (ferror (uptr->fileref)) {                           /* error? */
     sim_perror ("Card stacker I/O error");
     clearerr (uptr->fileref);
     if (iochk)
         return SCPE_IOERR;
     }
+uptr->pos = uptr->pos + strlen (cdr_buf);               /* update position */
 return SCPE_OK;
 }
 
@@ -375,7 +376,6 @@ if ((uptr->flags & UNIT_ATT) == 0)                      /* attached? */
     return SCPE_UNATT;
 fputs (cdp_buf, uptr->fileref);                         /* output card */
 fputc ('\n', uptr->fileref);                            /* plus new line */
-uptr->pos = ftell (uptr->fileref);                      /* update position */
 if (ferror (uptr->fileref)) {                           /* error? */
     sim_perror ("Card punch I/O error");
     clearerr (uptr->fileref);
@@ -383,6 +383,7 @@ if (ferror (uptr->fileref)) {                           /* error? */
         return SCPE_IOERR;
     ind[IN_PNCH] = 1;
     }
+uptr->pos = uptr->pos + strlen (cdp_buf) + 1;           /* update position */
 return SCPE_OK;
 }
 
diff --git a/I1401/i1401_lp.c b/I1401/i1401_lp.c
index 9598638b..ab71d4ab 100644
--- a/I1401/i1401_lp.c
+++ b/I1401/i1401_lp.c
@@ -1,6 +1,6 @@
 /* i1401_lp.c: IBM 1403 line printer simulator
 
-   Copyright (c) 1993-2015, Robert M. Supnik
+   Copyright (c) 1993-2021, 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 +25,7 @@
 
    lpt          1403 line printer
 
+   09-Jun-21    RMS     Removed use of ftell for pipe compatibility
    08-Mar-15    RMS     Added print to console option
    16-Apr-13    RMS     Fixed printer chain selection
    19-Jan-07    RMS     Added UNIT_TEXT flag
@@ -245,19 +246,19 @@ if ((lpt_unit.flags & UNIT_ATT) != 0) {                 /* attached? */
         ind[IN_LPT] = 1;
         sim_perror ("Line printer I/O error");
         clearerr (lpt_unit.fileref);
-        if (iochk)
+        if (iochk != 0)
             return SCPE_IOERR;
         }
-    lpt_unit.pos = ftell (lpt_unit.fileref);            /* update position */
+    lpt_unit.pos = lpt_unit.pos + strlen (buf);         /* update position */
     return SCPE_OK;
     }
-if ((lpt_unit.flags & UNIT_CONS) != 0) {               /* default to cons? */
-    if (buf[0] == '\n') {                              /* bare lf? */
-        inq_puts ("\r");                               /* cvt to crlf */
+if ((lpt_unit.flags & UNIT_CONS) != 0) {                /* default to cons? */
+    if (buf[0] == '\n') {                               /* bare lf? */
+        inq_puts ("\r");                                /* cvt to crlf */
         lpt_unit.pos = lpt_unit.pos + 1;
         }
     inq_puts (buf);
-    lpt_unit.pos = lpt_unit.pos + strlen (buf);
+    lpt_unit.pos = lpt_unit.pos + strlen (buf);         /* update position */
     return SCPE_OK;
     }
 return SCPE_UNATT;
diff --git a/I1620/i1620_cd.c b/I1620/i1620_cd.c
index 7c4273b0..0190da46 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) 2002-2017, Robert M. Supnik
+   Copyright (c) 2002-2021, 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 +26,7 @@
    cdr          1622 card reader
    cdp          1622 card punch
 
+   09-Jun-21    RMS     Removed use of ftell on output for pipe compatibility
    23-Jun-17    RMS     Unattached error does not set RDCHK/WRCHK
    09-Mar-17    RMS     Guardbanded translation table lookups (COVERITY)
    31-Jan-15    TFM     Changes to translation tables (Tom McBride)
@@ -528,13 +529,13 @@ cdp_buf[len] = '\n';                                    /* newline, null */
 cdp_buf[len + 1] = 0;
 
 fputs (cdp_buf, cdp_unit.fileref);                      /* write card */
-cdp_unit.pos = ftell (cdp_unit.fileref);                /* count char */
 if (ferror (cdp_unit.fileref)) {                        /* error? */
     ind[IN_WRCHK] = 1;
     sim_perror ("CDP I/O error");
     clearerr (cdp_unit.fileref);
     return SCPE_IOERR;
     }
+cdp_unit.pos = cdp_unit.pos + strlen (cdp_buf);         /* update position */
 return SCPE_OK;
 }
 
diff --git a/I1620/i1620_lp.c b/I1620/i1620_lp.c
index 8516056c..5daf0379 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) 2002-2017, Robert M. Supnik
+   Copyright (c) 2002-2021, 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 +25,7 @@
 
    lpt          1443 line printer
 
+   10-Jun-21    RMS     Removed use of ftell for pipe compatibility
    15-Jun-17    RMS     Fixed K constants and print-no-spacing (Tom McBride)
                         Added option to emulate form feed with newlines
    31-Jan-15    TFM     Fixed various problems ... see comments in code
@@ -279,7 +280,7 @@ return sta;
 
 t_stat lpt_print (uint32 flag)
 {
-int32 i;
+int32 i, cc;
 
 if ((lpt_unit.flags & UNIT_ATT) == 0) {                 /* not attached? */
     ind[IN_PRCHK] = 1;                                  /* pri check */
@@ -292,9 +293,11 @@ while ((lpt_bptr > 0) && (lpt_buf[lpt_bptr - 1] == ' '))
     lpt_buf[--lpt_bptr] = 0;                            /* trim buffer */
 if (lpt_bptr != 0) {                                    /* any line? */
     fputs (lpt_buf, lpt_unit.fileref);                  /* print */
-    if ((flag & 1) != 0)                                /* no space? */
+    cc = strlen (lpt_buf);
+    if ((flag & 1) != 0) {                              /* no space? */
         fputc ('\r', lpt_unit.fileref);                 /* bare return */
-    lpt_unit.pos = ftell (lpt_unit.fileref);            /* update pos */
+        cc++;
+        }
     lpt_buf_init ();                                    /* reinit buf */
     if (ferror (lpt_unit.fileref)) {                    /* error? */
         ind[IN_PRCHK] = 1;                              /* pri check */
@@ -302,6 +305,7 @@ if (lpt_bptr != 0) {                                    /* any line? */
         clearerr (lpt_unit.fileref);
         return SCPE_IOERR;
         }
+    lpt_unit.pos = lpt_unit.pos + (t_addr)cc;           /* update pos */
     }
 if ((flag & 1) == 0)                                    /* spacing? */
     return lpt_spcop (lpt_savctrl);                     /* execute */
@@ -336,17 +340,19 @@ return STOP_CCT;                                        /* runaway channel */
 
 t_stat lpt_space (int32 count, int32 sflag)
 {
-int32 i;
+int32 i, cc;
 
 cct_ptr = (cct_ptr + count) % cct_lnt;                  /* adv cct, mod lnt */
 if (sflag && CHP (0, cct[cct_ptr]) &&                   /* skip, top of form, */
-    ((lpt_unit.flags & UNIT_FF) != 0))                  /* and use form feeds? */
+    ((lpt_unit.flags & UNIT_FF) != 0)) {                /* and use form feeds? */
     fputs ("\n\f", lpt_unit.fileref);                   /* nl, ff */
+    cc = 2;
+    }
 else {
     for (i = 0; i < count; i++)                         /* count lines */
         fputc ('\n', lpt_unit.fileref);
+    cc = count;
     }
-lpt_unit.pos = ftell (lpt_unit.fileref);                /* update position */
 ind[IN_PRCH9] = CHP (9, cct[cct_ptr]) != 0;             /* set indicators */
 ind[IN_PRCH12] = CHP (12, cct[cct_ptr]) != 0;
 if (ferror (lpt_unit.fileref)) {                        /* error? */
@@ -355,6 +361,7 @@ if (ferror (lpt_unit.fileref)) {                        /* error? */
     clearerr (lpt_unit.fileref);
     return SCPE_IOERR;
     }
+lpt_unit.pos = lpt_unit.pos + (t_addr)cc;               /* update position */
 ind[IN_PRBSY] = 1;                                      /* print busy */
 sim_activate (&lpt_unit, lpt_unit.wait);                /* start timer */
 return SCPE_OK;
diff --git a/I7094/i7094_cd.c b/I7094/i7094_cd.c
index ae3bbe6b..94fdafc6 100644
--- a/I7094/i7094_cd.c
+++ b/I7094/i7094_cd.c
@@ -1,6 +1,6 @@
 /* i7094_cd.c: IBM 711/721 card reader/punch
 
-   Copyright (c) 2003-2017, Robert M. Supnik
+   Copyright (c) 2003-2021, 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 +26,7 @@
    cdr          711 card reader
    cdp          721 card punch
 
+   09-Jun-21    RMS     Removed use of ftell on output for pipe compatibility
    13-Mar-17    RMS     Annotated fall through in switch
    19-Mar-12    RMS     Fixed declaration of sim_switches (Mark Pizzolato)
    19-Jan-07    RMS     Added UNIT_TEXT
@@ -448,12 +449,12 @@ for (i = ((2 * CD_CHRLNT) + 1); (i > 0) &&
 cdp_cbuf[i++] = '\n';                                   /* append nl */
 cdp_cbuf[i++] = 0;                                      /* append nul */
 fputs (cdp_cbuf, uptr->fileref);                        /* write card */
-uptr->pos = ftell (uptr->fileref);                      /* update position */
 if (ferror (uptr->fileref)) {                           /* error? */
     sim_perror ("CDP I/O error");
     clearerr (uptr->fileref);
     return SCPE_IOERR;
     }
+uptr->pos = uptr->pos + strlen (cdp_cbuf);              /* update position */
 cdp_sta = CDS_END;                                      /* end state */
 sim_cancel (uptr);                                      /* cancel current */
 sim_activate (uptr, cdp_tstop);                         /* long timer */
diff --git a/I7094/i7094_lp.c b/I7094/i7094_lp.c
index 3f312583..19f6c4a0 100644
--- a/I7094/i7094_lp.c
+++ b/I7094/i7094_lp.c
@@ -1,6 +1,6 @@
 /* i7094_lp.c: IBM 716 line printer simulator
 
-   Copyright (c) 2003-2017, Robert M. Supnik
+   Copyright (c) 2003-2021, 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 +25,7 @@
 
    lpt          716 line printer
 
+   09-Jun-21    RMS     Removed use of ftell for pipe compatibility
    13-Mar-17    RMS     Fixed GET_PCHAIN macro (COVERITY)
    19-Jan-07    RMS     Added UNIT_TEXT flag
 
@@ -331,12 +332,12 @@ lpt_cbuf[i] = 0;                                        /* append nul */
 if (uptr->flags & UNIT_ATT) {                           /* file? */
     fputs (lpt_cbuf, uptr->fileref);                    /* write line */
     fputc ('\n', uptr->fileref);                        /* append nl */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* error? */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + strlen (lpt_cbuf) + 1;      /* update pos, add nl */
     }
 else if (uptr->flags & UNIT_CONS) {                     /* print to console? */
     for (i = 0; lpt_cbuf[i] != 0; i++)
diff --git a/Interdata/id_lp.c b/Interdata/id_lp.c
index 44cda00e..d6fa152a 100644
--- a/Interdata/id_lp.c
+++ b/Interdata/id_lp.c
@@ -1,6 +1,6 @@
 /* id_lp.c: Interdata line printer
 
-   Copyright (c) 2001-2008, Robert M. Supnik
+   Copyright (c) 2001-2021, 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 +25,7 @@
 
    lpt          M46-206 line printer
 
+   10-Jun-21    RMS     Removed use of ftell for pipe compatibility
    27-May-08    RMS     Fixed bug in printing test (Davis Johnson)
    19-Jan-07    RMS     Added UNIT_TEXT flag
    25-Apr-03    RMS     Revised for extended file support
@@ -72,8 +73,8 @@ t_stat lpt_svc (UNIT *uptr);
 t_stat lpt_reset (DEVICE *dptr);
 t_stat lpt_attach (UNIT *uptr, CONST char *cptr);
 t_stat lpt_bufout (UNIT *uptr);
-t_stat lpt_vfu (UNIT *uptr, int32 ch);
-t_stat lpt_spc (UNIT *uptr, int32 cnt);
+int32 lpt_vfu (UNIT *uptr, int32 ch);
+int32 lpt_spc (UNIT *uptr, int32 cnt);
 
 /* LPT data structures
 
@@ -158,8 +159,7 @@ return 0;
 
 t_stat lpt_svc (UNIT *uptr)
 {
-int32 t;
-t_stat r = SCPE_OK;
+int32 t, cc;
 
 lpt_sta = 0;                                            /* clear busy */
 if (lpt_arm)                                            /* armed? intr */
@@ -172,22 +172,27 @@ if (lpt_spnd || ((t >= LF) && (t < CR))) {              /* spc pend or spc op? *
     if (lpt_bufout (uptr) != SCPE_OK)                   /* print */
         return SCPE_IOERR;
     if ((t == 1) || (t == LF))                          /* single space */
-        lpt_spc (uptr, 1);
+        cc = lpt_spc (uptr, 1);
     else if (t == VT)                                   /* VT->VFU */
-        r = lpt_vfu (uptr, VT_VFU - 1);
+        cc = lpt_vfu (uptr, VT_VFU - 1);
     else if (t == 0xC)                                  /* FF->VFU */
-        r = lpt_vfu (uptr, FF_VFU - 1);
-    else if ((t >= SPC_BASE) && (t < VFU_BASE))
-        lpt_spc (uptr, t - SPC_BASE);                   /* space */
+        cc = lpt_vfu (uptr, FF_VFU - 1);
+    else if ((t >= SPC_BASE) && (t < VFU_BASE))         /* space */
+        cc = lpt_spc (uptr, t - SPC_BASE);
     else if ((t >= VFU_BASE) && (t < VFU_BASE + VFU_WIDTH))
-        r = lpt_vfu (uptr, t - VFU_BASE);               /* VFU */
-    else fputs ("\r", uptr->fileref);                   /* overprint */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
-    if (ferror (lpt_unit.fileref)) {
+        cc = lpt_vfu (uptr, t - VFU_BASE);              /* VFU */
+    else {
+        fputs ("\r", uptr->fileref);                    /* overprint */
+        cc = 1;
+        }
+    if (cc < 0)                                         /* VFU runaway? */
+        return STOP_VFU;
+    if (ferror (lpt_unit.fileref)) {                    /* I/O error? */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + (t_addr)cc;                /* update position */
     }
 else if (t == CR) {                                     /* CR? */
     lpt_spnd = 1;                                       /* set spc pend */
@@ -199,7 +204,7 @@ else if (t >= 0x20) {                                   /* printable? */
     if (lpt_bptr < LPT_WIDTH)
         lpxb[lpt_bptr++] = t;
     }
-return r;
+return SCPE_OK;
 }
 
 /* Printing and spacing routines */
@@ -214,12 +219,12 @@ for (i = LPT_WIDTH - 1; (i >= 0) && (lpxb[i] == ' '); i--)
     lpxb[i] = 0;                                        /* backscan line */
 if (lpxb[0]) {                                          /* any char left? */
     fputs (lpxb, uptr->fileref);                        /* write line */
-    lpt_unit.pos = ftell (uptr->fileref);               /* update position */
-    if (ferror (uptr->fileref)) {
+    if (ferror (uptr->fileref)) {                       /* I/O error? */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         r = SCPE_IOERR;
         }
+    lpt_unit.pos = lpt_unit.pos + strlen (lpxb);        /* update position */
     }   
 lpt_bptr = 0;                                           /* reset buffer */
 for (i = 0; i < LPT_WIDTH; i++)
diff --git a/NOVA/nova_lp.c b/NOVA/nova_lp.c
index 59de2380..eacaae36 100644
--- a/NOVA/nova_lp.c
+++ b/NOVA/nova_lp.c
@@ -1,6 +1,6 @@
 /* nova_lp.c: NOVA line printer simulator
 
-   Copyright (c) 1993-2008, Robert M. Supnik
+   Copyright (c) 1993-2021, 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 +25,7 @@
 
    lpt          line printer
 
+   09-Jun-21    RMS     Reverted use of ftell for pipe compatibility
    04-Jul-07    BKR     DEV_SET/CLR macros now used,
                         <FF>, <CR>, <LF> output character delay now contingent upon non-zero TIME value,
                         LPT can now be DISABLED
diff --git a/PDP1/pdp1_lp.c b/PDP1/pdp1_lp.c
index a27bc78e..223ffb1c 100644
--- a/PDP1/pdp1_lp.c
+++ b/PDP1/pdp1_lp.c
@@ -1,6 +1,6 @@
 /* pdp1_lp.c: PDP-1 line printer simulator
 
-   Copyright (c) 1993-2008, Robert M. Supnik
+   Copyright (c) 1993-2021, 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 +25,7 @@
 
    lpt          Type 62 line printer for the PDP-1
 
+   09-Jun-21    RMS     Removed use of ftell for pipe compatibility
    19-Jan-07    RMS     Added UNIT_TEXT flag
    21-Dec-06    RMS     Added 16-channel SBS support
    07-Sep-03    RMS     Changed ioc to ios
@@ -173,12 +174,12 @@ if (lpt_spc) {                                          /* space? */
     if ((uptr->flags & UNIT_ATT) == 0)                  /* attached? */
         return IORETURN (lpt_stopioe, SCPE_UNATT);
     fputs (lpt_cc[lpt_spc & 07], uptr->fileref);        /* print cctl */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* error? */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + strlen (lpt_cc[lpt_spc & 07]);
     lpt_ovrpr = 0;                                      /* dont overprint */
     }
 else {
@@ -188,12 +189,12 @@ else {
     if (lpt_ovrpr)                                      /* overprint? */
         fputc ('\r', uptr->fileref);
     fputs (lpt_buf, uptr->fileref);                     /* print buffer */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* test error */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + strlen (lpt_buf);           /* update position */
     lpt_bptr = 0;
     for (i = 0; i <= LPT_BSIZE; i++)                    /* clear buffer */
         lpt_buf[i] = 0;
diff --git a/PDP10/pdp10_lp20.c b/PDP10/pdp10_lp20.c
index e1a82127..a676be06 100644
--- a/PDP10/pdp10_lp20.c
+++ b/PDP10/pdp10_lp20.c
@@ -799,19 +799,18 @@ for (i = 0; i < cnt; i++) {                             /* print 'n' newlines; e
     fputc ('\n', lp20_unit->fileref);
     if (dvuadv) {                                       /* update DAVFU ptr */
         dvptr = (dvptr + cnt) % dvlnt;
-        if (davfu[dvptr] & (1 << DV_TOF)) {              /* at top of form? */
-            lppagc = (lppagc - 1) & PAGC_MASK;           /* decr page cntr */
+        if (davfu[dvptr] & (1 << DV_TOF)) {             /* at top of form? */
+            lppagc = (lppagc - 1) & PAGC_MASK;          /* decr page cntr */
             if (lppagc == 0) {
-                lpcsa = lpcsa | CSA_PZRO;                /* stop if zero */
+                lpcsa = lpcsa | CSA_PZRO;               /* stop if zero */
                 stoppc = TRUE;
                 }
             } /* At TOF */
         } /* update pointer */
     }
 lp20_unit->pos = (t_addr)sim_ftell (lp20_unit->fileref);
-if (stoppc)                                            /* Crossed one or more TOFs? */
+if (stoppc)                                            /* crossed one or more TOFs? */
     return FALSE;
-
 return TRUE;
 }
 
diff --git a/PDP11/pdp11_lp.c b/PDP11/pdp11_lp.c
index 0410e9ae..fb139dce 100644
--- a/PDP11/pdp11_lp.c
+++ b/PDP11/pdp11_lp.c
@@ -1,6 +1,6 @@
 /* pdp11_lp.c: PDP-11 line printer simulator
 
-   Copyright (c) 1993-2008, Robert M Supnik
+   Copyright (c) 1993-2021, 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 +25,7 @@
 
    lpt          LP11 line printer
 
+   20-Mar-21    RMS     Reverted use of ftell for pipe compatibility
    19-Jan-07    RMS     Added UNIT_TEXT flag
    07-Jul-05    RMS     Removed extraneous externs
    19-May-03    RMS     Revised for new conditional compilation scheme
diff --git a/PDP18B/pdp18b_lp.c b/PDP18B/pdp18b_lp.c
index b7ab1d1e..853a4c77 100644
--- a/PDP18B/pdp18b_lp.c
+++ b/PDP18B/pdp18b_lp.c
@@ -1,6 +1,6 @@
 /* pdp18b_lp.c: 18b PDP's line printer simulator
 
-   Copyright (c) 1993-2017, Robert M Supnik
+   Copyright (c) 1993-2021, 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"),
@@ -28,6 +28,7 @@
    lp09         (PDP-9,15) LP09 line printer
    lp15         (PDP-15)   LP15 line printer
 
+   09-Jun-21    RMS     Reverted use of ftell for pipe compatibility
    13-Mar-17    RMS     Annotated fall throughs in switch
    10-Mar-16    RMS     Added 3-cycle databreak set/show entry
    07-Mar-16    RMS     Revised for dynamically allocated memory
@@ -190,12 +191,12 @@ if (lp62_spc) {                                         /* space? */
     if ((uptr->flags & UNIT_ATT) == 0)                  /* attached? */
         return IORETURN (lp62_stopioe, SCPE_UNATT);
     fputs (lp62_cc[lp62_spc & 07], uptr->fileref);      /* print cctl */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* error? */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + strlen (lp62_cc[lp62_spc & 07]); /* update position */
     lp62_ovrpr = 0;                                     /* clear overprint */
     }
 else {
@@ -205,12 +206,13 @@ else {
     if (lp62_ovrpr)                                     /* overprint? */
         fputc ('\r', uptr->fileref);
     fputs (lp62_buf, uptr->fileref);                    /* print buffer */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* test error */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + strlen (lp62_buf) +         /* update position */
+        (lp62_ovrpr? 1: 0);                             /* including \r */
     lp62_bp = 0;
     for (i = 0; i <= LP62_BSIZE; i++)                   /* clear buffer */
         lp62_buf[i] = 0;
@@ -439,23 +441,23 @@ if ((lp647_iot & 020) == 0) {                           /* print? */
     for (i = 0; i < LP647_BSIZE; i++)                   /* clear buffer */
         lp647_buf[i] = 0;
     fputs (pbuf, uptr->fileref);                        /* print buffer */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* error? */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         lp647_bp = 0;
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + strlen (pbuf);              /* update position */
     lp647_bp = 0;                                       /* clear buffer ptr */
     }
 if (lp647_iot & 060) {                                  /* space? */
     fputs (lp647_cc[lp647_iot & 07], uptr->fileref);    /* write cctl */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* error? */
         sim_perror ("LPT I/O error");
         clearerr (uptr->fileref);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + strlen (lp647_cc[lp647_iot & 07]);
     }
 return SCPE_OK;
 }
@@ -838,7 +840,6 @@ for (more = 1; more != 0; ) {                           /* loop until ctrl */
             lp15_buf[lp15_bp] = 0;                      /* append nul */
             fputs (lp15_buf, uptr->fileref);            /* print line */
             fputs (ctrl[c[i] & 037], uptr->fileref);    /* space */
-            uptr->pos = ftell (uptr->fileref);
             if (ferror (uptr->fileref)) {               /* error? */
                 sim_perror ("LPT I/O error");
                 clearerr (uptr->fileref);
@@ -846,6 +847,8 @@ for (more = 1; more != 0; ) {                           /* loop until ctrl */
                 lp15_updsta (STA_DON | STA_ALM);
                 return SCPE_IOERR;
                 }
+            uptr->pos = uptr->pos + strlen (lp15_buf)   /* update position */
+                + strlen (ctrl[c[i] & 037]);            /* incl spacing */
             lp15_bp = more = 0;
             }
         else {
diff --git a/PDP8/pdp8_lp.c b/PDP8/pdp8_lp.c
index d352e825..fc2b62da 100644
--- a/PDP8/pdp8_lp.c
+++ b/PDP8/pdp8_lp.c
@@ -1,6 +1,6 @@
 /* pdp8_lp.c: PDP-8 line printer simulator
 
-   Copyright (c) 1993-2016, Robert M Supnik
+   Copyright (c) 1993-2021, 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"),
@@ -25,7 +25,8 @@
 
    lpt          LP8E line printer
 
-   16-Dec-16    DJG     Added IOT 6660 to allow WPS WS78 3.4 to print
+   20-Mar-21    RMS     Reverted use of ftell for pipe compatibility
+   15-Dec-16    RMS     Added LS8E decode (6660) for WPS8 (Dave Gesswein)
    19-Jan-07    RMS     Added UNIT_TEXT
    25-Apr-03    RMS     Revised for extended file support
    04-Oct-02    RMS     Added DIB, enable/disable, device number support
diff --git a/SDS/sds_lp.c b/SDS/sds_lp.c
index b06bdca9..183c8ed9 100644
--- a/SDS/sds_lp.c
+++ b/SDS/sds_lp.c
@@ -1,6 +1,6 @@
 /* sds_lp.c: SDS 940 line printer simulator
 
-   Copyright (c) 2001-2008, Robert M. Supnik
+   Copyright (c) 2001-2021, 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 +25,7 @@
 
    lpt          line printer
 
+   10-Jun-21    RMS     Removed use of ftell for pipe compatibility
    24-Nov-08    RMS     Fixed loss of carriage control position on space op
    19-Jan-07    RMS     Added UNIT_TEXT flag
    25-Apr-03    RMS     Revised for extended file support
@@ -61,13 +62,13 @@ DSPT lpt_tplt[] = {                                     /* template */
 t_stat lpt_svc (UNIT *uptr);
 t_stat lpt_reset (DEVICE *dptr);
 t_stat lpt_attach (UNIT *uptr, CONST char *cptr);
-t_stat lpt_crctl (UNIT *uptr, int32 ch);
-t_stat lpt_space (UNIT *uptr, int32 cnt);
-t_stat lpt_status (UNIT *uptr);
+int32 lpt_crctl (UNIT *uptr, int32 ch);
+int32 lpt_space (UNIT *uptr, int32 cnt);
+t_stat lpt_status (UNIT *uptr, int32 cnt);
 t_stat lpt_bufout (UNIT *uptr);
 void lpt_end_op (int32 fl);
 t_stat lpt (uint32 fnc, uint32 inst, uint32 *dat);
-int8 sds_to_ascii(int8 c);
+int8 sds_to_ascii (int8 c);
 
 /* LPT data structures
 
@@ -181,7 +182,7 @@ switch (fnc) {                                          /* case function */
         break;
 
     case IO_WRITE:                                      /* write */
-        asc = sds_to_ascii(*dat);                       /* convert data */
+        asc = sds_to_ascii (*dat);                      /* convert data */
         xfr_req = xfr_req & ~XFR_LPT;                   /* clr xfr flag */
         if (lpt_bptr < LPT_WIDTH)                       /* store data */
             lpt_buf[lpt_bptr++] = asc;
@@ -201,6 +202,7 @@ return SCPE_OK;
 t_stat lpt_svc (UNIT *uptr)
 {
 t_stat r = SCPE_OK;
+int32 cc = 0;
 
 if (lpt_sta & SET_XFR)                                  /* need lpt xfr? */
     chan_set_ordy (lpt_dib.chan);
@@ -212,10 +214,14 @@ if (lpt_sta & SET_SPC) {                                /* spacing? */
     if (uptr->flags & UNIT_ATT) {                       /* attached? */
         int32 ln = LPT_GETLN (lpt_spc);                 /* get lines, ch */
         if (lpt_spc & 0200)                             /* n lines? */
-            lpt_space (uptr, ln);                       /* upspace */
-        else lpt_crctl (uptr, ln);                      /* carriage ctl */
+            cc = lpt_space (uptr, ln);                  /* upspace */
+        else {
+            cc = lpt_crctl (uptr, ln);                  /* carriage ctl */
+            if (cc < 0)                                 /* tape error? */
+                return STOP_CCT;
+            }
         }
-    r = lpt_status (uptr);                              /* update status */
+    r = lpt_status (uptr, cc);                          /* update status */
     }
 lpt_sta = 0;                                            /* clear state */
 return r;
@@ -226,28 +232,30 @@ return r;
 t_stat lpt_bufout (UNIT *uptr)
 {
 int32 i;
+int32 cc = 0;
 
 if ((uptr->flags & UNIT_ATT) && lpt_bptr) {             /* attached? */
     for (i = LPT_WIDTH - 1; (i >= 0) && (lpt_buf[i] == ' '); i--)
         lpt_buf[i] = 0;                                 /* trim line */
     fputs (lpt_buf, uptr->fileref);                     /* write line */
+    cc = strlen (lpt_buf);
     lpt_bptr = 0;
     }
-return lpt_status (uptr);                               /* return status */
+return lpt_status (uptr, cc);                           /* return status */
 }
 
 /* Status update after I/O */
 
-t_stat lpt_status (UNIT *uptr)
+t_stat lpt_status (UNIT *uptr, int32 cnt)
 {
 if (uptr->flags & UNIT_ATT) {                           /* attached? */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* I/O error? */
         lpt_end_op (CHF_EOR | CHF_ERR);                 /* set err, disc */
         sim_perror ("LPT I/O error");                   /* print msg */
         clearerr (uptr->fileref);
         return SCPE_IOERR;                              /* ret error */
         }
+    uptr->pos = uptr->pos + (t_addr)cnt;                /* udpate position */
     }
 else {
     lpt_end_op (CHF_EOR | CHF_ERR);                     /* set err, disc */
@@ -273,40 +281,40 @@ return;
 
 /* Carriage control */
 
-t_stat lpt_crctl (UNIT *uptr, int32 ch)
+int32 lpt_crctl (UNIT *uptr, int32 ch)
 {
 int32 i, j;
 
 if ((ch == 1) && CHP (ch, lpt_cct[0])) {                /* top of form? */
     fputs ("\f\n", uptr->fileref);                      /* ff + nl */
     lpt_ccp = 0;                                        /* top of page */
-    return SCPE_OK;
+    return 2;
     }
 for (i = 1; i < lpt_ccl + 1; i++) {                     /* sweep thru cct */
     lpt_ccp = (lpt_ccp + 1) % lpt_ccl;                  /* adv pointer */
     if (CHP (ch, lpt_cct[lpt_ccp])) {                   /* chan punched? */
         for (j = 0; j < i; j++)
             fputc ('\n', uptr->fileref);
-        return SCPE_OK;
+        return i;
         }
     }
-return STOP_CCT;                                        /* runaway channel */
+return -1;                                              /* runaway channel */
 }
 
 /* Spacing */
 
-t_stat lpt_space (UNIT *uptr, int32 cnt)
+int32 lpt_space (UNIT *uptr, int32 cnt)
 {
 int32 i;
 
-if (cnt == 0)
+if (cnt == 0) {                                         /* overprint */
      fputc ('\r', uptr->fileref);
-else {
-    for (i = 0; i < cnt; i++)
-        fputc ('\n', uptr->fileref);
-    lpt_ccp = (lpt_ccp + cnt) % lpt_ccl;
-    }
-return SCPE_OK;
+     return 1;
+    } 
+for (i = 0; i < cnt; i++)                               /* 'cnt' newlines */
+    fputc ('\n', uptr->fileref);
+lpt_ccp = (lpt_ccp + cnt) % lpt_ccl;                    /* advance CCT */
+return cnt;
 }
 
 /* Reset routine */
diff --git a/sigma/sigma_lp.c b/sigma/sigma_lp.c
index 6d579adc..5a25633f 100644
--- a/sigma/sigma_lp.c
+++ b/sigma/sigma_lp.c
@@ -1,6 +1,6 @@
 /* sigma_lp.c: Sigma 7440/7450 line printer
 
-   Copyright (c) 2007-2017, Robert M. Supnik
+   Copyright (c) 2007-2021, 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 +25,7 @@
 
    lp           7440/7445 or 7450 line printer
 
+   10-Jun-2021  RMS     Removed use of ftell for pipe compatibility
    09-Mar-2017  RMS     Fixed unclosed file returns in CCT load (COVERITY)
 */
 
@@ -300,7 +301,7 @@ switch (lp_cmd) {                                       /* case on state */
 return SCPE_OK;
 }
 
-/* Format routine */
+/* Format routine - uses skip or space */
 
 uint32 lp_fmt (UNIT *uptr)
 {
@@ -327,7 +328,7 @@ else if ((c & ~CCH_MASK) == FMT_SKP)                    /* skip? */
 return 0;
 }
 
-/* Skip to channel */
+/* Skip to channel - uses space */
 
 uint32 lp_skip (UNIT *uptr, uint32 ch)
 {
@@ -345,22 +346,25 @@ return lp_space (uptr, lp_cctl, TRUE);                  /* space max */
 
 uint32 lp_space (UNIT *uptr, uint32 cnt, t_bool skp)
 {
-uint32 i;
+uint32 i, cc;
 
 lp_cctp = (lp_cctp + cnt) % lp_cctl;                    /* adv cct, mod lnt */
-if (skp && CHP (CH_TOF, lp_cct[lp_cctp]))               /* skip, TOF? */
-        fputs ("\f", uptr->fileref);                    /* ff */
+if (skp && CHP (CH_TOF, lp_cct[lp_cctp])) {             /* skip, TOF? */
+        fputc ('\f', uptr->fileref);                    /* ff */
+        cc = 1;
+        }
     else {                                              /* space */
         for (i = 0; i < cnt; i++)
             fputc ('\n', uptr->fileref);
+        cc = cnt;
         }
-uptr->pos = ftell (uptr->fileref);                      /* update position */
 if (ferror (uptr->fileref)) {                           /* error? */
     perror ("Line printer I/O error");
     clearerr (uptr->fileref);
     chan_set_chf (lp_dib.dva, CHF_XMDE);
     return SCPE_IOERR;
     }
+uptr->pos = uptr->pos + cc;                             /* update position */
 return 0;
 }
 
@@ -386,16 +390,16 @@ for (bp = 0, st = 0; (bp < max) && !st; bp++) {          /* fill buffer */
 if ((lp_model == LP_7440) || lp_pass) {                 /* ready to print? */
     lp_pass = 0;
     for (i = BUF_LNT4; (i > 0) && (lp_buf[i - 1] == ' '); i--) ; /* trim */
-    if (i)                                              /* write line */
+    if (i != 0)                                         /* write line */
         sim_fwrite (lp_buf, 1, i, uptr->fileref);
     fputc (lp_inh? '\r': '\n', uptr->fileref);          /* cr or nl */
-    uptr->pos = ftell (uptr->fileref);                  /* update position */
     if (ferror (uptr->fileref)) {                       /* error? */
         perror ("Line printer I/O error");
         clearerr (uptr->fileref);
         chan_set_chf (lp_dib.dva, CHF_XMDE);
         return SCPE_IOERR;
         }
+    uptr->pos = uptr->pos + i + 1;                      /* update position */
     if ((lp_model == LP_7440) &&                        /* 7440? */
         ((bp != BUF_LNT4) || (st != CHS_ZBC)) &&        /* check lnt err */
         chan_set_chf (lp_dib.dva, CHF_LNTE))