diff --git a/B5500/b5500_cpu.c b/B5500/b5500_cpu.c
index 245d0a92..8dcc8e6e 100644
--- a/B5500/b5500_cpu.c
+++ b/B5500/b5500_cpu.c
@@ -101,7 +101,7 @@
 #define UNIT_MSIZE      (7 << UNIT_V_MSIZE)
 #define MEMAMOUNT(x)    (x << UNIT_V_MSIZE)
 
-#define TMR_RTC         1
+#define TMR_RTC         0
 
 #define HIST_MAX        5000
 #define HIST_MIN        64
@@ -700,10 +700,6 @@ int mkint() {
                 B <<= 3;
                 exp_b--;
             }
-            if (exp_b != 0) {
-                B = 0;
-                return 1;
-            }
         }
         if (f && B != 0)
             B |= MSIGN;
@@ -3855,8 +3851,7 @@ cpu_reset(DEVICE * dptr)
     sim_brk_types = sim_brk_dflt = SWMASK('E') | SWMASK('A') | SWMASK('B');
     hst_p = 0;
 
-    sim_register_clock_unit (&cpu_unit[0]);
-    sim_rtcn_init (cpu_unit[0].wait, TMR_RTC);
+    sim_rtcn_init_unit (&cpu_unit[0], cpu_unit[0].wait, TMR_RTC);
     sim_activate(&cpu_unit[0], cpu_unit[0].wait) ;
 
     return SCPE_OK;
diff --git a/B5500/b5500_defs.h b/B5500/b5500_defs.h
index e79ddf56..9f11639d 100644
--- a/B5500/b5500_defs.h
+++ b/B5500/b5500_defs.h
@@ -1,4 +1,4 @@
-/* b5500_defs.h: Burroughs 5500 simulator definitions 
+/* b5500_defs.h: Burroughs 5500 simulator definitions
 
    Copyright (c) 2016, Richard Cornwell
 
@@ -52,18 +52,13 @@ extern uint8            loading;                        /* System booting flag *
 
 /* Debuging controls */
 #define DEBUG_CHAN      0x0000001       /* Show channel fetchs */
-#define DEBUG_TRAP      0x0000002       /* Show CPU Traps */
 #define DEBUG_CMD       0x0000004       /* Show device commands */
 #define DEBUG_DATA      0x0000008       /* Show data transfers */
 #define DEBUG_DETAIL    0x0000010       /* Show details */
 #define DEBUG_EXP       0x0000020       /* Show error conditions */
-#define DEBUG_SNS       0x0000040       /* Shows sense data for 7909 devs */
-#define DEBUG_CTSS      0x0000080       /* Shows CTSS specail instructions */
-#define DEBUG_PROT      0x0000100       /* Protection traps */
 
 extern DEBTAB dev_debug[];
 
-
 /* Returns from device commands */
 #define SCPE_BUSY       (1)     /* Device is active */
 #define SCPE_NODEV      (2)     /* No device exists */
@@ -77,23 +72,6 @@ typedef struct _opcode
 }
 t_opcode;
 
-/* I/O Command codes */
-#define IO_RDS  1       /* Read record */
-#define IO_BSR  2       /* Backspace one record */
-#define IO_BSF  3       /* Backspace one file */
-#define IO_WRS  4       /* Write one record */
-#define IO_WEF  5       /* Write eof */
-#define IO_REW  6       /* Rewind */
-#define IO_DRS  7       /* Set unit offline */
-#define IO_SDL  8       /* Set density low */
-#define IO_SDH  9       /* Set density high */
-#define IO_RUN  10      /* Rewind and unload unit */
-#define IO_TRS  11      /* Check it unit ready */
-#define IO_CTL  12      /* Io control device specific */
-#define IO_RDB  13      /* Read backwards */
-#define IO_SKR  14      /* Skip record forward */
-#define IO_ERG  15      /* Erase next records from tape */
-
 
 t_stat chan_reset(DEVICE *);
 t_stat chan_boot(t_uint64);
@@ -127,49 +105,49 @@ extern t_stat      fprint_sym(FILE *, t_addr, t_value *, UNIT *, int32);
 extern int32       tmxr_poll;
 
 /* Generic devices common to all */
-extern DEVICE      cpu_dev; 
-extern UNIT        cpu_unit[]; 
+extern DEVICE      cpu_dev;
+extern UNIT        cpu_unit[];
 extern REG         cpu_reg[];
-extern DEVICE      chan_dev; 
+extern DEVICE      chan_dev;
 
 /* Global device definitions */
 #if (NUM_DEVS_CDR > 0) | (NUM_DEVS_CDP > 0)
-extern DEVICE       cdr_dev; 
+extern DEVICE       cdr_dev;
 extern t_stat       card_cmd(uint16, uint16, uint8, uint16 *);
 #endif
 
 #if (NUM_DEVS_CDP > 0)
-extern DEVICE       cdp_dev; 
+extern DEVICE       cdp_dev;
 #endif
 
 #if (NUM_DEVS_LPR > 0)
-extern DEVICE       lpr_dev; 
+extern DEVICE       lpr_dev;
 extern t_stat       lpr_cmd(uint16, uint16, uint8, uint16 *);
 #endif
 
 #if (NUM_DEVS_CON > 0)
-extern DEVICE       con_dev; 
+extern DEVICE       con_dev;
 extern t_stat       con_cmd(uint16, uint16, uint8, uint16 *);
 #endif
 
 #if (NUM_DEVS_DTC > 0)
-extern DEVICE      dtc_dev; 
+extern DEVICE      dtc_dev;
 extern t_stat      dtc_cmd(uint16, uint16, uint8, uint16 *);
 #endif
 
-#if (NUM_DEVS_DR > 0)   
-extern DEVICE      drm_dev; 
+#if (NUM_DEVS_DR > 0)
+extern DEVICE      drm_dev;
 extern t_stat      drm_cmd(uint16, uint16, uint8, uint16 *, uint8);
 #endif
 
 #if (NUM_DEVS_DSK > 0)
-extern DEVICE      dsk_dev; 
+extern DEVICE      dsk_dev;
 extern t_stat      dsk_cmd(uint16, uint16, uint8, uint16 *);
-extern DEVICE      esu_dev; 
+extern DEVICE      esu_dev;
 #endif
 
-#if (NUM_DEVS_MT > 0) 
-extern DEVICE      mt_dev; 
+#if (NUM_DEVS_MT > 0)
+extern DEVICE      mt_dev;
 extern t_stat      mt_cmd(uint16, uint16, uint8, uint16 *);
 #endif  /* NUM_DEVS_MT */
 
@@ -494,7 +472,7 @@ extern t_stat      mt_cmd(uint16, uint16, uint8, uint16 *);
 #define SSALF           00000010000000000LL
 #define SVARF           00000000100000000LL
 #define SCWMF           00000000000100000LL
-#define FFIELD          00000007777700000LL     
+#define FFIELD          00000007777700000LL
 #define FFIELD_V        15
 #define REPFLD          00000770000000000LL
 #define REPFLD_V        30
@@ -503,7 +481,7 @@ extern t_stat      mt_cmd(uint16, uint16, uint8, uint16 *);
 #define PROGF           00400000000000000LL
 #define RGH             00340700000000000LL     /* Return Control Word +FFIELD and CORE */
 #define RGH_V           33
-#define RKV             00034070000000000LL    
+#define RKV             00034070000000000LL
 #define RKV_V           30
 #define RL              00003000000000000LL     /* Save L register */
 #define RL_V            36
@@ -511,7 +489,7 @@ extern t_stat      mt_cmd(uint16, uint16, uint8, uint16 *);
 #define HMASK           00007777770000000LL
 #define DEV_DRUM_RD     01000000000000000LL
 #define DEVMASK         00760000000000000LL
-#define D_MASK          00777777777777777LL     
+#define D_MASK          00777777777777777LL
 #define DEV_V           40
 #define DEV_WC          00017770000000000LL
 #define DEV_WC_V        30
@@ -535,9 +513,9 @@ extern t_stat      mt_cmd(uint16, uint16, uint8, uint16 *);
 #define DEV_EOF         00000000004000000LL     /* D21 */
 #define DEV_MEMERR      00000000010000000LL     /* D22 */
 #define DEV_RESULT      00000000037700000LL
-#define DEV_EOT         01000100001000000LL     
-#define DEV_BOT         01000200001000000LL     
-#define DEV_BLANK       01000400001000000LL     
+#define DEV_EOT         01000100001000000LL
+#define DEV_BOT         01000200001000000LL
+#define DEV_BLANK       01000400001000000LL
 
 #define DRUM1_DEV       004                     /* 00100  (4) */
 #define DSK1_DEV        006                     /* 00110  (6) */
diff --git a/B5500/b5500_dtc.c b/B5500/b5500_dtc.c
index b899d29b..966a9a16 100644
--- a/B5500/b5500_dtc.c
+++ b/B5500/b5500_dtc.c
@@ -1,4 +1,4 @@
-/* b5500_dtc.c: Burrioughs 5500 Data Communications 
+/* b5500_dtc.c: Burrioughs 5500 Data Communications
 
    Copyright (c) 2016, Richard Cornwell
 
@@ -26,7 +26,7 @@
 #include "sim_sock.h"
 #include "sim_tmxr.h"
 
-#if (NUM_DEVS_DTC > 0) 
+#if (NUM_DEVS_DTC > 0)
 
 #define UNIT_DTC        UNIT_ATTABLE | UNIT_DISABLE | UNIT_IDLE
 
@@ -44,8 +44,8 @@
 #define DTCSTA_GM       0020    /* Ignore GM on transfer */
 #define DTCSTA_BUF      0017    /* Buffer Number */
 
-/* Interrogate 
-        D28 - Busy         DEV_ERROR 
+/* Interrogate
+        D28 - Busy         DEV_ERROR
         D27 - Write Ready  DEV_EOF
         D24 - Read Ready   DEV_IORD  */
 /* Abnormal flag = DEV_WCFLG */
@@ -85,11 +85,11 @@
             BufIdle -> BufWrite (set GM if set.)
             BufReadReady ->  0x20 (EOF).
             BufInputBusy, BufWrite -> 0x30
-                -> 0x34 (EOF,ERROR) 
+                -> 0x34 (EOF,ERROR)
             BufWriteRdy -> BufWrite.
 
         Write Done:
-             BufOutBusy. 
+             BufOutBusy.
 
         Read:
             BufNotReady -> 0x34 (EOF,ERROR,NR)
@@ -112,7 +112,7 @@
 */
 
 /* Translate chars
-       
+
         output:
       ! -> LF.
       < -> RO.
@@ -121,23 +121,23 @@
       ~ -> End of message.
 
         input:
-      ~/_/CR -> End of message. 
-                BufReadRdy, IRQ. 
+      ~/_/CR -> End of message.
+                BufReadRdy, IRQ.
       </BS -> Back up one char.
       !/   -> Disconnect insert }
-                BufReadRdy, IRQ. 
-      ^B    -> Clear input. 
+                BufReadRdy, IRQ.
+      ^B    -> Clear input.
                 BufIdle
       ^E   -> set abnormal, buffer to BufWriteRdy.
       ^L   -> Clear input.
                 BufIdle
       ?    -> Set abnormal
       Char: Buf to BufInputBsy. Insert char.
-            if Fullbuff, BufReadRdy, IRQ, 
- 
+            if Fullbuff, BufReadRdy, IRQ,
+
 */
- 
-        
+
+
 
 t_stat              dtc_srv(UNIT *);
 t_stat              dtco_srv(UNIT *);
@@ -217,28 +217,28 @@ t_stat dtc_cmd(uint16 cmd, uint16 dev, uint8 chan, uint16 *wc)
     uptr = &dtc_unit[0];
 
     /* If unit disabled return error */
-    if (uptr->flags & UNIT_DIS) 
+    if (uptr->flags & UNIT_DIS)
         return SCPE_NODEV;
 
     if ((uptr->flags & UNIT_ATT) == 0)
         return SCPE_UNATT;
 
     /* Check if drive is ready to recieve a command */
-    if ((uptr->u5 & DTC_RDY) == 0) 
+    if ((uptr->u5 & DTC_RDY) == 0)
         return SCPE_BUSY;
 
     uptr->u5 = chan;
     ttu = (*wc & DTCSTA_TTU) >> 5;
-    buf = (*wc & DTCSTA_BUF); 
+    buf = (*wc & DTCSTA_BUF);
     /* Set the Terminal unit. */
-    if (ttu == 0) 
+    if (ttu == 0)
         uptr->u4 = -1;
     else {
         uptr->u4 = buf + ((ttu-1) * 15);
     }
     if (*wc & DTCSTA_GM)
         uptr->u5 |= DTC_IGNGM;
-    if (cmd & DTCSTA_READ) 
+    if (cmd & DTCSTA_READ)
         uptr->u5 |= DTC_RD;
     else if (cmd & DTCSTA_INHIBIT)
         uptr->u5 |= DTC_INQ;
@@ -250,12 +250,12 @@ t_stat dtc_cmd(uint16 cmd, uint16 dev, uint8 chan, uint16 *wc)
 
     sim_debug(DEBUG_CMD, &dtc_dev, "Datacomm access %s %06o %d %04o\n",
                 (uptr->u5 & DTC_RD) ? "read" : ((uptr->u5 & DTC_INQ) ? "inq" :
-                  ((uptr->u5 & DTC_WR) ? "write" : "unknown")), 
+                  ((uptr->u5 & DTC_WR) ? "write" : "unknown")),
                  uptr->u5, uptr->u4, *wc);
     sim_activate(uptr, 5000);
     return SCPE_OK;
 }
-        
+
 
 /* Handle processing terminal controller commands */
 t_stat dtc_srv(UNIT * uptr)
@@ -266,16 +266,15 @@ t_stat dtc_srv(UNIT * uptr)
     int                 buf;
     int                 i;
     int                 line = uptr->u4;
-    
 
-    
+
     /* Process interrage command */
     if (uptr->u5 & DTC_INQ) {
         if (line == -1) {
             buf = -1;
             for(i = 0; i < DTC_MLINES; i++) {
                 if (dtc_lstatus[i]& BufIRQ) {
-                   if ((dtc_lstatus[i] & BufSMASK) == BufReadRdy) 
+                   if ((dtc_lstatus[i] & BufSMASK) == BufReadRdy)
                       buf = i;
                    if ((dtc_lstatus[i] & BufSMASK) == BufWriteRdy ||
                        (dtc_lstatus[i] & BufSMASK) == BufIdle) {
@@ -306,7 +305,6 @@ t_stat dtc_srv(UNIT * uptr)
                 }
                 dtc_lstatus[line] &= ~BufIRQ;
             }
-            sim_debug(DEBUG_DETAIL, &dtc_dev, " %03o ", dtc_lstatus[i]);
         } else {
             if (line > dtc_desc.lines) {
                 chan_set_notrdy(chan);
@@ -359,7 +357,7 @@ t_stat dtc_srv(UNIT * uptr)
             chan_set_end(chan);
             uptr->u5 = DTC_RDY;
             return SCPE_OK;
-        } 
+        }
         /* Validate that we can send data to buffer */
         i = dtc_lstatus[line] & BufSMASK;
         switch(i) {
@@ -373,7 +371,7 @@ t_stat dtc_srv(UNIT * uptr)
                 chan_set_eof(chan);
                 chan_set_end(chan);
                 uptr->u5 = DTC_RDY;
-                sim_debug(DEBUG_DETAIL, &dtc_dev, "Datacomm write busy %d %d\n", 
+                sim_debug(DEBUG_DETAIL, &dtc_dev, "Datacomm write busy %d %d\n",
                         line, i);
                 return SCPE_OK;
 
@@ -390,7 +388,7 @@ t_stat dtc_srv(UNIT * uptr)
         case BufWrite:
                 break;
         }
-        
+
         if (chan_read_char(chan, &ch, dtc_bufptr[line] >= dtc_blimit[line])) {
                 sim_debug(DEBUG_DETAIL, &dtc_dev, "Datacomm write done %d %d ",
                          line, dtc_bufptr[line]);
@@ -439,17 +437,22 @@ t_stat dtc_srv(UNIT * uptr)
             chan_set_end(chan);
             uptr->u5 = DTC_RDY;
             return SCPE_OK;
-        } 
+        }
         /* Validate that we can send data to buffer */
         i = dtc_lstatus[line] & BufSMASK;
         switch(i) {
         case BufNotReady:
                 chan_set_notrdy(chan);
+                /* Fall through */
         case BufInputBusy:
                 chan_set_error(chan);
+                /* Fall through */
         case BufWriteRdy:
+                /* Fall through */
         case BufOutBusy:
+                /* Fall through */
         case BufIdle:
+                /* Fall through */
         case BufWrite:
                 chan_set_eof(chan);
                 chan_set_end(chan);
@@ -479,7 +482,7 @@ t_stat dtc_srv(UNIT * uptr)
                      chan_set_gm(chan);
                      sim_debug(DEBUG_DETAIL, &dtc_dev, "gm ");
                 }
-                if (dtc_lstatus[line] & BufAbnormal) 
+                if (dtc_lstatus[line] & BufAbnormal)
                      chan_set_wcflg(chan);
                 if (dtc_ldsc[line].conn == 0)   /* connected? */
                     dtc_lstatus[line] = BufIRQ|BufNotReady;
@@ -521,7 +524,7 @@ dtco_srv(UNIT * uptr)
         dtc_lstatus[ln] = BufIRQ|BufAbnormal|BufWriteRdy;
         IAR |= IRQ_12;
         sim_debug(DEBUG_DETAIL, &dtc_dev, "Datacomm connect %d\n", ln);
-    } 
+    }
 
     /* For each line that is in idle state enable recieve */
     for (ln = 0; ln < dtc_desc.lines; ln++) {
@@ -536,8 +539,10 @@ dtco_srv(UNIT * uptr)
         if (dtc_ldsc[ln].conn == 0) {   /* connected? */
              switch(dtc_lstatus[ln] & BufSMASK) {
              case BufIdle:              /* Idle, throw in EOT */
+                /* Fall through */
              case BufWriteRdy:          /* Awaiting output, terminate */
                   dtc_bufptr[ln] = 0;
+                /* Fall through */
              case BufInputBusy:         /* reading, terminate with EOT */
                   dtc_buf[ln][dtc_bufptr[ln]++] = 017;
                   dtc_bsize[ln] = dtc_bufptr[ln];
@@ -549,7 +554,7 @@ dtco_srv(UNIT * uptr)
                   dtc_bsize[ln] = 0;
                   IAR |= IRQ_12;
                   break;
-             default:                   /* Other cases, ignore until 
+             default:                   /* Other cases, ignore until
                                            in better state */
                   break;
              break;
@@ -559,9 +564,9 @@ dtco_srv(UNIT * uptr)
         switch(dtc_lstatus[ln] & BufSMASK) {
         case BufIdle:
              /* If we have any data to receive */
-             if (tmxr_rqln(&dtc_ldsc[ln]) > 0) 
+             if (tmxr_rqln(&dtc_ldsc[ln]) > 0)
                 dtc_lstatus[ln] = BufInputBusy;
-             else 
+             else
                 break;          /* Nothing to do */
              sim_debug(DEBUG_DETAIL, &dtc_dev, "Datacomm recieve %d idle\n",
                          ln);
@@ -577,7 +582,7 @@ dtco_srv(UNIT * uptr)
                        dtc_lstatus[ln] &= ~(BufSMASK);
                        dtc_lstatus[ln] |= BufIRQ|BufAbnormal|BufWriteRdy;
                        IAR |= IRQ_12;
-                       sim_debug(DEBUG_DETAIL, &dtc_dev, 
+                       sim_debug(DEBUG_DETAIL, &dtc_dev,
                                         "Datacomm recieve ENQ %d\n", ln);
                        t = 0;
                        break;
@@ -597,7 +602,9 @@ dtco_srv(UNIT * uptr)
                        /* Fall through to next */
 
                  case '\r':
+                       /* Fall through */
                  case '\n':
+                       /* Fall through */
                  case '~':
                        dtc_lstatus[ln] &= ~BufSMASK;
                        dtc_lstatus[ln] |= BufIRQ|BufReadRdy;
@@ -625,11 +632,11 @@ dtco_srv(UNIT * uptr)
                           tmxr_putc_ln(&dtc_ldsc[ln], '\007');
                        }
                        c1 = 0;
-                       sim_debug(DEBUG_DATA, &dtc_dev, 
+                       sim_debug(DEBUG_DATA, &dtc_dev,
                                 "Datacomm recieve %d backspace %d\n", ln, dtc_bufptr[ln]);
                        break;
                  case '?':
-                       sim_debug(DEBUG_DATA, &dtc_dev, 
+                       sim_debug(DEBUG_DATA, &dtc_dev,
                                 "Datacomm recieve %d ?\n", ln);
                        dtc_lstatus[ln] |= BufAbnormal;
                        tmxr_putc_ln(&dtc_ldsc[ln], '?');
@@ -655,7 +662,7 @@ dtco_srv(UNIT * uptr)
                        break;
                  }
              }
-                
+
              break;
         case BufOutBusy:
                 /* Get next char and send to output */
@@ -684,7 +691,7 @@ dtco_srv(UNIT * uptr)
                     t = 0;
                     continue;   /* On to next line */
                  }
-                 sim_debug(DEBUG_DATA, &dtc_dev, 
+                 sim_debug(DEBUG_DATA, &dtc_dev,
                         "Datacomm transmit %d %02o %c\n", ln, c&077, c1);
                  tmxr_putc_ln(&dtc_ldsc[ln], c1);
                  if (c1 == '\n') {
@@ -715,7 +722,7 @@ dtco_srv(UNIT * uptr)
 }
 
 
-t_stat 
+t_stat
 dtc_reset(DEVICE *dptr) {
    if (dtc_unit[0].flags & UNIT_ATT) {
        sim_activate(&dtc_unit[1], 100); /* quick poll */
@@ -777,6 +784,7 @@ t_stat dtc_setnl (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
         return r;
     if ((newln == 0) || (newln > DTC_MLINES))
         return SCPE_ARG;
+    newln--;
     if (newln < dtc_desc.lines) {
         for (i = newln, t = 0; i < dtc_desc.lines; i++)
             t = t | dtc_ldsc[i].conn;
diff --git a/B5500/b5500_mt.c b/B5500/b5500_mt.c
index ac373a55..e6e98865 100644
--- a/B5500/b5500_mt.c
+++ b/B5500/b5500_mt.c
@@ -159,7 +159,7 @@ mt_cmd(uint16 cmd, uint16 dev, uint8 chan, uint16 *wc)
     int         unit = dev >> 1;
 
     /* Make sure valid drive number */
-    if (unit > NUM_DEVS_MT || unit < 0)
+    if (unit > (NUM_DEVS_MT - 1) || unit < 0)
         return SCPE_NODEV;
 
     uptr = &mt_unit[unit];
@@ -199,7 +199,7 @@ mt_cmd(uint16 cmd, uint16 dev, uint8 chan, uint16 *wc)
 
     *wc = 0;    /* So no overide occurs */
 
-    /* Convert command to correct type */ 
+    /* Convert command to correct type */
     if (cmd & URCSTA_DIRECT)
         uptr->u5 |= MT_BACK;
     uptr->u6 = 0;
@@ -257,7 +257,7 @@ t_stat mt_error(UNIT * uptr, int chan, t_stat r, DEVICE * dptr)
         sim_debug(DEBUG_EXP, dptr, "BOT ");
         break;
     case MTSE_UNATT:            /* unattached */
-    default: 
+    default:
         sim_debug(DEBUG_EXP, dptr, "%d ", r);
     }
     uptr->u5 &= ~(MT_CMD|MT_BIN);
@@ -309,8 +309,8 @@ t_stat mt_srv(UNIT * uptr)
 
     switch (cmd) {
     /* Handle interrogate */
-    case MT_INT: 
-         if (sim_tape_wrp(uptr)) 
+    case MT_INT:
+         if (sim_tape_wrp(uptr))
             chan_set_wrp(chan);
          uptr->u5 &= ~(MT_CMD|MT_BIN);
          uptr->u5 |= MT_RDY;
@@ -334,7 +334,7 @@ t_stat mt_srv(UNIT * uptr)
                     ch = 017;
                     (void)chan_write_char(chan, &ch, 1);
                     sim_activate(uptr, 4000);
-                } else { 
+                } else {
                     sim_debug(DEBUG_DETAIL, dptr, "r=%d\n", r);
                     sim_activate(uptr, 5000);
                 }
@@ -369,7 +369,7 @@ t_stat mt_srv(UNIT * uptr)
               }
         }
 
-        if (chan_write_char(chan, &ch, 
+        if (chan_write_char(chan, &ch,
                              (((uint32)uptr->u6) >= uptr->hwmark) ? 1 : 0)) {
                 sim_debug(DEBUG_DATA, dptr, "Read unit=%d %d EOR\n", unit,
                          uptr->hwmark-uptr->u6);
@@ -398,7 +398,7 @@ t_stat mt_srv(UNIT * uptr)
                     ch = 017;
                     (void)chan_write_char(chan, &ch, 1);
                     sim_activate(uptr, 4000);
-                } else { 
+                } else {
                     uptr->u5 |= MT_BSY;
                     sim_debug(DEBUG_DETAIL, dptr, "r=%d\n", r);
                     sim_activate(uptr, 100);
@@ -465,7 +465,7 @@ t_stat mt_srv(UNIT * uptr)
                  sim_debug(DEBUG_DETAIL, dptr, "Write Mark unit=%d\n", unit);
                  r = sim_tape_wrtmk(uptr);
             } else {
-                sim_debug(DEBUG_DETAIL, dptr, 
+                sim_debug(DEBUG_DETAIL, dptr,
                         "Write unit=%d Block %d %s chars\n", unit, reclen,
                                 (uptr->u5 & MT_BIN)? "bin": "bcd");
                 r = sim_tape_wrrecf(uptr, &mt_buffer[chan][0], reclen);
@@ -477,10 +477,10 @@ t_stat mt_srv(UNIT * uptr)
             /* Copy data to buffer */
             ch &= 077;
             ch |= parity_table[ch];
-            if ((uptr->u5 & MT_BIN)) 
+            if ((uptr->u5 & MT_BIN))
                 ch ^= 0100;
             /* Don't write out even parity zeros */
-            if (ch != 0) 
+            if (ch != 0)
                 mt_buffer[chan][uptr->u6++] = ch;
             sim_debug(DEBUG_DATA, dptr, "Write data unit=%d %d %03o\n",
                       unit, uptr->u6, ch);
@@ -505,7 +505,7 @@ t_stat mt_srv(UNIT * uptr)
                     sim_debug(DEBUG_DETAIL, dptr, "TM ");
                     reclen = 1;
                     chan_set_eof(chan);
-                } else { 
+                } else {
                     sim_debug(DEBUG_DETAIL, dptr, "r=%d ", r);
                     reclen = 10;
                 }
@@ -534,7 +534,7 @@ t_stat mt_srv(UNIT * uptr)
                     sim_debug(DEBUG_DETAIL, dptr, "TM ");
                     reclen = 1;
                     chan_set_eof(chan);
-                } else { 
+                } else {
                     reclen = 10;
                     sim_debug(DEBUG_DETAIL, dptr, "r=%d ", r);
                 }
@@ -572,7 +572,7 @@ mt_attach(UNIT * uptr, CONST char *file)
 
     if ((r = sim_tape_attach(uptr, file)) != SCPE_OK)
         return r;
-    uptr->u5 |= MT_LOADED|MT_BOT; 
+    uptr->u5 |= MT_LOADED|MT_BOT;
     sim_activate(uptr, 50000);
     return SCPE_OK;
 }
@@ -590,8 +590,8 @@ mt_reset(DEVICE *dptr)
 {
     int i;
 
-    /* Scan all devices and enable those that 
-       are loaded. This is to allow tapes that 
+    /* Scan all devices and enable those that
+       are loaded. This is to allow tapes that
        are mounted prior to boot to be recognized
        at later. Also disconnect all devices no
        longer connected. */
diff --git a/B5500/b5500_sys.c b/B5500/b5500_sys.c
index 5dff9024..28dfc65e 100644
--- a/B5500/b5500_sys.c
+++ b/B5500/b5500_sys.c
@@ -90,8 +90,8 @@ DEBTAB              dev_debug[] = {
 };
 
 
-uint8                parity_table[64] = { 
-    /* 0    1    2    3    4    5    6    7 */ 
+uint8                parity_table[64] = {
+    /* 0    1    2    3    4    5    6    7 */
     0000, 0100, 0100, 0000, 0100, 0000, 0000, 0100,
     0100, 0000, 0000, 0100, 0000, 0100, 0100, 0000,
     0100, 0000, 0000, 0100, 0000, 0100, 0100, 0000,
@@ -103,15 +103,15 @@ uint8                parity_table[64] = {
 };
 
 uint8           mem_to_ascii[64] = {
-   /* x0   x1   x2   x3   x4   x5   x6   x7 */ 
+   /* x0   x1   x2   x3   x4   x5   x6   x7 */
      '0', '1', '2', '3', '4', '5', '6', '7',     /* 0x */
      '8', '9', '#', '@', '?', ':', '>', '}',     /* 1x */
      '+', 'A', 'B', 'C', 'D', 'E', 'F', 'G',     /* 2x */
      'H', 'I', '.', '[', '&', '(', '<', '~',     /* 3x */
-     '|', 'J', 'K', 'L', 'M', 'N', 'O', 'P',     /* 4x */ 
-     'Q', 'R', '$', '*', '-', ')', ';', '{',     /* 5x */ 
-     ' ', '/', 'S', 'T', 'U', 'V', 'W', 'X',     /* 6x */ 
-     'Y', 'Z', ',', '%', '!', '=', ']', '"'      /* 7x */ 
+     '|', 'J', 'K', 'L', 'M', 'N', 'O', 'P',     /* 4x */
+     'Q', 'R', '$', '*', '-', ')', ';', '{',     /* 5x */
+     ' ', '/', 'S', 'T', 'U', 'V', 'W', 'X',     /* 6x */
+     'Y', 'Z', ',', '%', '!', '=', ']', '"'      /* 7x */
 };
 
 const char          con_to_ascii[64] = {
@@ -349,13 +349,13 @@ print_opcode(FILE * of, t_value val, t_opcode * tab)
     while (tab->name != NULL) {
         switch(tab->type) {
         case TYPE_A:
-                if (op != tab->op) 
+                if (op != tab->op)
                    break;
                 fputs(tab->name, of);
                 fputs("       ",of);
                 return;
         case TYPE_B:
-                if ((op & 077) != tab->op) 
+                if ((op & 077) != tab->op)
                    break;
                 fputs(tab->name, of);
                 fputc(' ',of);
@@ -431,7 +431,7 @@ fprint_sym(FILE * of, t_addr addr, t_value * val, UNIT * uptr, int32 sw)
         fputc('\'', of);
     }
     if (sw & SWMASK('F')) {     /* Floating point/Descriptor */
-    }   
+    }
     return SCPE_OK;
 }
 
@@ -474,10 +474,10 @@ parse_sym(CONST char *cptr, t_addr addr, UNIT * uptr, t_value * val, int32 sw)
 
         /* Grab opcode */
         cptr = get_glyph(cptr, opcode, 0);
-        
+
         op = 0;
         opr = -1;
-        if((op = find_opcode(opcode, 
+        if((op = find_opcode(opcode,
                 (SWMASK('W') ? word_ops : char_ops))) == 0) {
             return SCPE_UNK;
         }
@@ -492,25 +492,25 @@ parse_sym(CONST char *cptr, t_addr addr, UNIT * uptr, t_value * val, int32 sw)
             cptr++;
         switch (op->type) {
         case TYPE_A:
-                if (opr >= 0) 
+                if (opr >= 0)
                    return SCPE_2MARG;
                 *val = op->op;
                 return SCPE_OK;
 
         case TYPE_B:
-                if (opr < 0 || opr > 64) 
+                if (opr < 0 || opr > 64)
                    return SCPE_ARG;
                 *val = (opr << 6) | op->op;
                 return SCPE_OK;
 
         case TYPE_C:
-                if (opr < 0 || opr > 16) 
+                if (opr < 0 || opr > 16)
                    return SCPE_ARG;
                 *val = (opr << 8) | op->op;
                 return SCPE_OK;
 
         case TYPE_D:
-                if (opr < 0 || opr > 1024) 
+                if (opr < 0 || opr > 1024)
                    return SCPE_ARG;
                 *val = (opr << 2) | op->op;
                 return SCPE_OK;
@@ -532,10 +532,4 @@ parse_sym(CONST char *cptr, t_addr addr, UNIT * uptr, t_value * val, int32 sw)
     }
     *val = d;
     return SCPE_OK;
-
-/* Symbolic input, continued */
-
-    if (*cptr != 0)
-        return SCPE_ARG;        /* junk at end? */
-    return SCPE_OK;
 }
diff --git a/B5500/b5500_urec.c b/B5500/b5500_urec.c
index b603c78b..b158655e 100644
--- a/B5500/b5500_urec.c
+++ b/B5500/b5500_urec.c
@@ -234,7 +234,7 @@ DEVICE              con_dev = {
 t_stat card_cmd(uint16 cmd, uint16 dev, uint8 chan, uint16 *wc)
 {
     UNIT        *uptr;
-    int                 u;
+    int          u;
 
     if (dev == CARD1_DEV)
         u = 0;
@@ -355,7 +355,7 @@ cdr_srv(UNIT *uptr) {
 
     /* Copy next column over */
     if (uptr->u5 & URCSTA_CARD &&
-        uptr->u4 <= ((uptr->u5 & URCSTA_BIN) ? 160 : 80)) {
+        uptr->u4 < ((uptr->u5 & URCSTA_BIN) ? 160 : 80)) {
         struct _card_data   *data;
         uint8                ch = 0;
         int                  u = (uptr - cdr_unit);
@@ -384,6 +384,8 @@ cdr_srv(UNIT *uptr) {
                         break;  /* Translate ? to error*/
             }
         }
+        sim_debug(DEBUG_DATA, &cdr_dev, "cdr %d: Char > %03o '%c' %d\n", u, ch,
+                        sim_six_to_ascii[ch & 077], uptr->u4);
         if(chan_write_char(chan, &ch, 0)) {
             uptr->u5 &= ~(URCSTA_ACTIVE|URCSTA_CARD);
             chan_set_end(chan);
@@ -396,8 +398,18 @@ cdr_srv(UNIT *uptr) {
             uptr->u4++;
             sim_activate(uptr, 100);
         }
-        sim_debug(DEBUG_DATA, &cdr_dev, "cdr %d: Char > %03o '%c' %d\n", u, ch,
-                        sim_six_to_ascii[ch & 077], uptr->u4);
+    }
+
+    /* Check if last column */
+    if (uptr->u5 & URCSTA_CARD &&
+        uptr->u4 == ((uptr->u5 & URCSTA_BIN) ? 160 : 80)) {
+
+        uptr->u5 &= ~(URCSTA_ACTIVE|URCSTA_CARD);
+        chan_set_end(chan);
+        /* Drop ready a bit after the last card is read */
+        if (sim_card_eof(uptr)) {
+            uptr->u5 |= URCSTA_EOF;
+        }
     }
     return SCPE_OK;
 }
@@ -502,7 +514,7 @@ cdp_srv(UNIT *uptr) {
     }
 
     /* Copy next column over */
-    if (uptr->u5 & URCSTA_ACTIVE && uptr->u4 <= 80) {
+    if (uptr->u5 & URCSTA_ACTIVE && uptr->u4 < 80) {
         struct _card_data   *data;
         uint8               ch = 0;
 
@@ -518,6 +530,12 @@ cdp_srv(UNIT *uptr) {
         }
         sim_activate(uptr, 10);
     }
+
+    /* Check if last column */
+    if (uptr->u5 & URCSTA_ACTIVE && uptr->u4 == 80) {
+        uptr->u5 |= URCSTA_BUSY|URCSTA_FULL;
+        uptr->u5 &= ~URCSTA_ACTIVE;
+    }
     return SCPE_OK;
 }
 
@@ -945,6 +963,7 @@ con_srv(UNIT *uptr) {
            switch (ch) {
            case 033:
                 con_data[0].inptr = 0;
+                /* Fall through */
            case '\r':
            case '\n':
                 uptr->u5 &= ~URCSTA_INPUT;