diff --git a/scp.c b/scp.c
index 2bc28be9..86a8680e 100644
--- a/scp.c
+++ b/scp.c
@@ -1826,7 +1826,7 @@ return SCPE_OK;
 
 t_stat show_unit (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag)
 {
-int32 u = uptr - dptr->units;
+int32 u = (int32)(uptr - dptr->units);
 
 if (flag > 1)
     fprintf (st, "  %s%d", sim_dname (dptr), u);
@@ -2460,7 +2460,7 @@ if (uptr->flags & UNIT_BUFABLE) {                       /* buffer? */
     if (uptr->filebuf == NULL)                          /* no buffer? */
         return attach_err (uptr, SCPE_MEM);             /* error */
     if (!sim_quiet) printf ("%s: buffering file in memory\n", sim_dname (dptr));
-    uptr->hwmark = sim_fread (uptr->filebuf,            /* read file */
+    uptr->hwmark = (uint32)sim_fread (uptr->filebuf,    /* read file */
         SZ_D (dptr), cap, uptr->fileref);
     uptr->flags = uptr->flags | UNIT_BUF;               /* set buffered */
     }
@@ -2985,7 +2985,7 @@ for ( ;; ) {                                            /* device loop */
                 READ_I (blkcnt);                        /* block count */
                 if (blkcnt < 0)                         /* compressed? */
                     limit = -blkcnt;
-                else limit = sim_fread (mbuf, sz, blkcnt, rfile);
+                else limit = (int32)sim_fread (mbuf, sz, blkcnt, rfile);
                 if (limit <= 0)                         /* invalid or err? */
                     return SCPE_IOERR;
                 for (j = 0; j < limit; j++, k = k + (dptr->aincr)) {
@@ -3766,7 +3766,7 @@ for (i = 0, j = addr; i < sim_emax; i++, j = j + dptr->aincr) {
             SZ_LOAD (sz, sim_eval[i], uptr->filebuf, loc);
             }
         else {
-            sim_fseek (uptr->fileref, sz * loc, SEEK_SET);
+            sim_fseek (uptr->fileref, (t_addr)(sz * loc), SEEK_SET);
             sim_fread (&sim_eval[i], sz, 1, uptr->fileref);
             if ((feof (uptr->fileref)) &&
                !(uptr->flags & UNIT_FIX)) {
@@ -3857,7 +3857,7 @@ for (i = 0, j = addr; i < count; i++, j = j + dptr->aincr) {
                 uptr->hwmark = (uint32) loc + 1;
             }
         else {
-            sim_fseek (uptr->fileref, sz * loc, SEEK_SET);
+            sim_fseek (uptr->fileref, (t_addr)(sz * loc), SEEK_SET);
             sim_fwrite (&sim_eval[i], sz, 1, uptr->fileref);
             if (ferror (uptr->fileref)) {
                 clearerr (uptr->fileref);
@@ -4384,7 +4384,7 @@ REG *find_reg (char *cptr, char **optr, DEVICE *dptr)
 {
 char *tptr;
 REG *rptr;
-uint32 slnt;
+size_t slnt;
 
 if ((cptr == NULL) || (dptr == NULL) || (dptr->registers == NULL))
     return NULL;
@@ -4569,7 +4569,8 @@ return pptr;
 
 SCHTAB *get_search (char *cptr, int32 radix, SCHTAB *schptr)
 {
-int32 c, logop, cmpop;
+int32 c;
+size_t logop, cmpop;
 t_value logval, cmpval;
 char *sptr, *tptr;
 const char logstr[] = "|&^", cmpstr[] = "=!><";
@@ -4599,11 +4600,11 @@ for (logop = cmpop = -1; c = *cptr++; ) {               /* loop thru clauses */
     else return NULL;
     }                                                   /* end for */
 if (logop >= 0) {
-    schptr->logic = logop;
+    schptr->logic = (int32)logop;
     schptr->mask = logval;
     }
 if (cmpop >= 0) {
-    schptr->boolop = cmpop;
+    schptr->boolop = (int32)cmpop;
     schptr->comp = cmpval;
     }
 return schptr;
diff --git a/sim_disk.c b/sim_disk.c
index c431601b..2f852262 100644
--- a/sim_disk.c
+++ b/sim_disk.c
@@ -473,7 +473,7 @@ if (!err) {
         memset (&buf[i*ctx->xfer_element_size], 0, tbc-(i*ctx->xfer_element_size));
     err = ferror (uptr->fileref);
     if ((!err) && (sectsread))
-        *sectsread = (i*ctx->xfer_element_size+ctx->sector_size-1)/ctx->sector_size;
+        *sectsread = (t_seccnt)((i*ctx->xfer_element_size+ctx->sector_size-1)/ctx->sector_size);
     }
 return err;
 }
@@ -587,7 +587,7 @@ if (!err) {
     i = sim_fwrite (buf, ctx->xfer_element_size, tbc/ctx->xfer_element_size, uptr->fileref);
     err = ferror (uptr->fileref);
     if ((!err) && (sectswritten))
-        *sectswritten = (i*ctx->xfer_element_size+ctx->sector_size-1)/ctx->sector_size;
+        *sectswritten = (t_seccnt)((i*ctx->xfer_element_size+ctx->sector_size-1)/ctx->sector_size);
     }
 return err;
 }
@@ -826,7 +826,7 @@ if (sim_switches & SWMASK ('C')) {                      /* create vhd disk & cop
     else {
         uint8 *copy_buf = malloc (1024*1024);
         t_lba lba;
-        t_seccnt sectors_per_buffer = (1024*1024)/sector_size;
+        t_seccnt sectors_per_buffer = (t_seccnt)((1024*1024)/sector_size);
         t_lba total_sectors = (t_lba)(uptr->capac/sector_size);
         t_seccnt sects = sectors_per_buffer;
 
@@ -894,12 +894,12 @@ uptr->disk_ctx = ctx = (struct disk_context *)calloc(1, sizeof(struct disk_conte
 if ((uptr->filename == NULL) || (uptr->disk_ctx == NULL))
     return _err_return (uptr, SCPE_MEM);
 strncpy (uptr->filename, cptr, CBUFSIZE);               /* save name */
-ctx->sector_size = sector_size;                         /* save sector_size */
-ctx->xfer_element_size = xfer_element_size;             /* save xfer_element_size */
+ctx->sector_size = (uint32)sector_size;                 /* save sector_size */
+ctx->xfer_element_size = (uint32)xfer_element_size;     /* save xfer_element_size */
 ctx->dptr = dptr;                                       /* save DEVICE pointer */
 ctx->dbit = dbit;                                       /* save debug bit */
 ctx->auto_format = auto_format;                         /* save that we auto selected format */
-ctx->storage_sector_size = sector_size;                 /* Default */
+ctx->storage_sector_size = (uint32)sector_size;         /* Default */
 if (sim_switches & SWMASK ('R')) {                      /* read only? */
     if ((uptr->flags & UNIT_ROABLE) == 0)               /* allowed? */
         return _err_return (uptr, SCPE_NORO);           /* no, error */
@@ -1470,7 +1470,7 @@ if (Removable) {
 return TRUE;
 }
 
-static t_stat sim_os_disk_info_raw (FILE *Disk, size_t *sector_size, uint32 *removable)
+static t_stat sim_os_disk_info_raw (FILE *Disk, uint32 *sector_size, uint32 *removable)
 {
 DWORD IoctlReturnSize;
 #ifndef __GNUC__
@@ -2822,7 +2822,7 @@ ExpandToFullPath (const char *szFileSpec,
                   size_t BufferSize)
 {
 #ifdef _WIN32
-GetFullPathNameA (szFileSpec, BufferSize, szFullFileSpecBuffer, NULL);
+GetFullPathNameA (szFileSpec, (DWORD)BufferSize, szFullFileSpecBuffer, NULL);
 #else
 strncpy (szFullFileSpecBuffer, szFileSpec, BufferSize);
 #endif
@@ -2905,14 +2905,14 @@ hVHD->Dynamic.ParentLocatorEntries[6].PlatformDataOffset = NtoHll (LocatorPositi
 if (RelativeMatch) {
     memcpy (hVHD->Dynamic.ParentLocatorEntries[5].PlatformCode, "W2ru", 4);
     hVHD->Dynamic.ParentLocatorEntries[5].PlatformDataSpace = NtoHl (BytesPerSector);
-    hVHD->Dynamic.ParentLocatorEntries[5].PlatformDataLength = NtoHl (2*strlen(RelativeParentVHDPath));
+    hVHD->Dynamic.ParentLocatorEntries[5].PlatformDataLength = NtoHl ((uint32)(2*strlen(RelativeParentVHDPath)));
     hVHD->Dynamic.ParentLocatorEntries[5].Reserved = 0;
     hVHD->Dynamic.ParentLocatorEntries[5].PlatformDataOffset = NtoHll (LocatorPosition+LocatorsWritten*BytesPerSector);
     ++LocatorsWritten;
     }
 memcpy (hVHD->Dynamic.ParentLocatorEntries[4].PlatformCode, "W2ku", 4);
 hVHD->Dynamic.ParentLocatorEntries[4].PlatformDataSpace = NtoHl (BytesPerSector);
-hVHD->Dynamic.ParentLocatorEntries[4].PlatformDataLength = NtoHl (2*strlen(FullParentVHDPath));
+hVHD->Dynamic.ParentLocatorEntries[4].PlatformDataLength = NtoHl ((uint32)(2*strlen(FullParentVHDPath)));
 hVHD->Dynamic.ParentLocatorEntries[4].Reserved = 0;
 hVHD->Dynamic.ParentLocatorEntries[4].PlatformDataOffset = NtoHll (LocatorPosition+LocatorsWritten*BytesPerSector);
 ++LocatorsWritten;
diff --git a/sim_fio.c b/sim_fio.c
index 671e8f39..c80c8020 100644
--- a/sim_fio.c
+++ b/sim_fio.c
@@ -96,7 +96,7 @@ if (sim_end || (count == 0) || (size == sizeof (char)))
     return;
 for (j = 0, dptr = sptr = (unsigned char *) bptr;       /* loop on items */
      j < count; j++) { 
-    for (k = size - 1; k >= (((int32) size + 1) / 2); k--) {
+    for (k = (int32)(size - 1); k >= (((int32) size + 1) / 2); k--) {
         by = *sptr;                                     /* swap end-for-end */
         *sptr++ = *(dptr + k);
         *(dptr + k) = by;
@@ -130,7 +130,7 @@ if (sim_end || (size == sizeof (char))) {
     return;
     }
 for (j = 0; j < count; j++) {                           /* loop on items */
-    for (k = size - 1; k >= 0; k--)
+    for (k = (int32)(size - 1); k >= 0; k--)
         *(dptr + k) = *sptr++;
     dptr = dptr + size;
     }
@@ -153,7 +153,7 @@ if (lcnt) nbuf = nbuf + 1;
 else lcnt = nelem;
 total = 0;
 sptr = (unsigned char *) bptr;                          /* init input ptr */
-for (i = nbuf; i > 0; i--) {                            /* loop on buffers */
+for (i = (int32)nbuf; i > 0; i--) {                     /* loop on buffers */
     c = (i == 1)? lcnt: nelem;
     sim_buf_copy_swapped (sim_flip, sptr, size, c);
     sptr = sptr + size * count;
diff --git a/sim_sock.c b/sim_sock.c
index 63c0f573..027f7f1d 100644
--- a/sim_sock.c
+++ b/sim_sock.c
@@ -90,7 +90,7 @@ void sim_close_sock (SOCKET sock, t_bool master)
 return;
 }
 
-SOCKET sim_setnonblock (SOCKET sock)
+int32 sim_setnonblock (SOCKET sock)
 {
 return SOCKET_ERROR;
 }
@@ -289,7 +289,7 @@ return;
 }
 
 #if defined (_WIN32)                                    /* Windows */
-SOCKET sim_setnonblock (SOCKET sock)
+int32 sim_setnonblock (SOCKET sock)
 {
 unsigned long non_block = 1;
 
@@ -297,7 +297,7 @@ return ioctlsocket (sock, FIONBIO, &non_block);         /* set nonblocking */
 }
 
 #elif defined (VMS)                                     /* VMS */
-SOCKET sim_setnonblock (SOCKET sock)
+int32 sim_setnonblock (SOCKET sock)
 {
 int non_block = 1;
 
diff --git a/sim_sock.h b/sim_sock.h
index 5d469519..d8531cbe 100644
--- a/sim_sock.h
+++ b/sim_sock.h
@@ -83,6 +83,6 @@ int32 sim_check_conn (SOCKET sock, t_bool rd);
 int32 sim_read_sock (SOCKET sock, char *buf, int32 nbytes);
 int32 sim_write_sock (SOCKET sock, char *msg, int32 nbytes);
 void sim_close_sock (SOCKET sock, t_bool master);
-SOCKET sim_setnonblock (SOCKET sock);
+int32 sim_setnonblock (SOCKET sock);
 
 #endif
diff --git a/sim_tape.c b/sim_tape.c
index c6ee3cae..fd7003fe 100644
--- a/sim_tape.c
+++ b/sim_tape.c
@@ -764,7 +764,7 @@ if (rbc > max) {                                        /* rec out of range? */
     uptr->pos = opos;
     return MTSE_INVRL;
     }
-i = sim_fread (buf, sizeof (uint8), rbc, uptr->fileref);/* read record */
+i = (t_mtrlnt)sim_fread (buf, sizeof (uint8), rbc, uptr->fileref);/* read record */
 if (ferror (uptr->fileref)) {                           /* error? */
     MT_SET_PNU (uptr);
     uptr->pos = opos;
@@ -823,7 +823,7 @@ if (st = sim_tape_rdlntr (uptr, &tbc))                  /* read rec lnt */
 *bc = rbc = MTR_L (tbc);                                /* strip error flag */
 if (rbc > max)                                          /* rec out of range? */
     return MTSE_INVRL;
-i = sim_fread (buf, sizeof (uint8), rbc, uptr->fileref);/* read record */
+i = (t_mtrlnt)sim_fread (buf, sizeof (uint8), rbc, uptr->fileref);/* read record */
 if (ferror (uptr->fileref))                             /* error? */
     return sim_tape_ioerr (uptr);
 for ( ; i < rbc; i++)                                   /* fill with 0's */
@@ -1765,7 +1765,8 @@ uint32 sim_tape_tpc_map (UNIT *uptr, t_addr *map)
 {
 t_addr tpos;
 t_tpclnt bc;
-uint32 i, objc;
+size_t i;
+uint32 objc;
 
 if ((uptr == NULL) || (uptr->fileref == NULL))
     return 0;
diff --git a/sim_tmxr.c b/sim_tmxr.c
index 1fc4b25f..4cb866de 100644
--- a/sim_tmxr.c
+++ b/sim_tmxr.c
@@ -212,14 +212,14 @@ if (newsock != INVALID_SOCKET) {                        /* got a live one? */
         lp->cnms = sim_os_msec ();                      /* time of conn */
         if (!mp->buffered) {
             lp->txbpi = 0;                              /* init buf pointers */
-            lp->txbpr = lp->txbsz - strlen (msgbuf);
+            lp->txbpr = (int32)(lp->txbsz - strlen (msgbuf));
             lp->rxcnt = lp->txcnt = lp->txdrp = 0;      /* init counters */
             }
         else
             if (lp->txcnt > lp->txbsz)
                 lp->txbpr = (lp->txbpi + 1) % lp->txbsz;
             else
-                lp->txbpr = lp->txbsz - strlen (msgbuf);
+                lp->txbpr = (int32)(lp->txbsz - strlen (msgbuf));
         lp->tsta = 0;                                   /* init telnet state */
         lp->xmte = 1;                                   /* enable transmit */
         lp->dstb = 0;                                   /* default bin mode */
@@ -228,7 +228,7 @@ if (newsock != INVALID_SOCKET) {                        /* got a live one? */
         tmxr_linemsg (lp, msgbuf);                      /* beginning of buffer */
         lp->txbpi = psave;                              /* restore insertion pointer */
         tmxr_poll_tx (mp);                              /* flush output */
-        lp->txcnt -= strlen (msgbuf);                   /* adjust statistics */
+        lp->txcnt -= (int32)strlen (msgbuf);            /* adjust statistics */
         return i;
         }
     }                                                   /* end if newsock */
@@ -752,7 +752,7 @@ return SCPE_NOFNC;
 void tmxr_msg (SOCKET sock, char *msg)
 {
 if (sock)
-    sim_write_sock (sock, msg, strlen (msg));
+    sim_write_sock (sock, msg, (int32)strlen (msg));
 return;
 }
 
@@ -760,7 +760,7 @@ void tmxr_linemsg (TMLN *lp, char *msg)
 {
 int32 len;
 
-for (len = strlen (msg); len > 0; --len)
+for (len = (int32)strlen (msg); len > 0; --len)
     tmxr_putc_ln (lp, *msg++);
 return;
 }