diff --git a/converters/fsio/dos11.c b/converters/fsio/dos11.c
index 60581e3..96e44bb 100644
--- a/converters/fsio/dos11.c
+++ b/converters/fsio/dos11.c
@@ -40,45 +40,8 @@
 
 #include "fsio.h"
 
-/*
- * Tables for the bitmap allocator
- */
-uint16_t bits[16] = {
-  0000001, 0000002, 0000004, 0000010, 0000020, 0000040, 0000100, 0000200,
-  0000400, 0001000, 0002000, 0004000, 0010000, 0020000, 0040000, 0100000
-};
-
-uint16_t lowbits[16] = {
-  0000001, 0000003, 0000007, 0000017, 0000037, 0000077, 0000177, 0000377,
-  0000777, 0001777, 0003777, 0007777, 0017777, 0037777, 0077777, 0177777
-};
-
-uint16_t highbits[16] = {
-  0100000, 0140000, 0160000, 0170000, 0174000, 0176000, 0177000, 0177400,
-  0177600, 0177700, 0177740, 0177760, 0177770, 0177774, 0177776, 0177777
-};
-
-/*
- * Table of # of zeroes in each bye value.
- */
-uint8_t zeroes[256] = {
-  8,  7,  7,  6,  7,  6,  6,  5,  7,  6,  6,  5,  6,  5,  5,  4,
-  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
-  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
-  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
-  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
-  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
-  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
-  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
-  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
-  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
-  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
-  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
-  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
-  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
-  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
-  4,  3,  3,  2,  3,  2,  2,  1,  3,  2,  2,  1,  2,  1,  1,  0,
-};
+extern uint16_t bits[], lowbits[], highbits[];
+extern uint8_t zeroes[];
 
 /*
  * Table of "set" commands
@@ -1277,10 +1240,11 @@ int dos11ReadBlock(
   void *buf
 )
 {
-  void *buffer = buf == NULL ? mount->dos11data.buf : buf;
+  struct DOS11data *data = &mount->dos11data;
+  void *buffer = buf == NULL ? data->buf : buf;
   int status;
 
-  if (block >= mount->dos11data.blocks) {
+  if (block >= data->blocks) {
     ERROR("Attempt to read block (%u) outside file system \"%s\"\n",
           block, mount->name);
     return 0;
@@ -1309,7 +1273,7 @@ int dos11ReadBlock(
  *
  *      mount           - pointer to a mounted file system descriptor
  *      block           - logical block # in the range 0 - N
- *      buf             - buffer to receive data, if NULL use the mount
+ *      buf             - buffer to containing data, if NULL use the mount
  *                        point specific buffer
  *
  * Outputs:
@@ -1327,10 +1291,11 @@ int dos11WriteBlock(
   void *buf
 )
 {
-  void *buffer = buf == NULL ? mount->dos11data.buf : buf;
+  struct DOS11data *data = &mount->dos11data;
+  void *buffer = buf == NULL ? data->buf : buf;
   int status;
 
-  if (block >= mount->dos11data.blocks) {
+  if (block >= data->blocks) {
     ERROR("Attempt to write block (%u) outside file system \"%s\"\n",
           block, mount->name);
     return 0;
@@ -2142,10 +2107,11 @@ static void *dos11OpenFileR(
   char *fname
 )
 {
+  struct DOS11data *data = &mount->dos11data;
   struct dos11OpenFile *file;
   struct dos11FileSpec spec;
-  uint8_t user = mount->dos11data.user;
-  uint8_t group = mount->dos11data.group;
+  uint8_t user = data->user;
+  uint8_t group = data->group;
 
   if (dos11ParseFilespec(fname, &spec, user, group, DOS11_M_NONE) == 0) {
     fprintf(stderr, "Failed to parse filename \"%s\"\n", fname);
@@ -2200,11 +2166,12 @@ static void *dos11OpenFileW(
   off_t size
 )
 {
+  struct DOS11data *data = &mount->dos11data;
   struct dos11OpenFile *file;
   struct dos11FileSpec spec;
   unsigned long contig = (size + mount->blocksz - 1) / mount->blocksz;
-  uint8_t user = mount->dos11data.user;
-  uint8_t group = mount->dos11data.group;
+  uint8_t user = data->user;
+  uint8_t group = data->group;
 
   if (SWISSET('c') && (contig == 0)) {
       fprintf(stderr,"DOS-11 contiguous files must be at least 1 block\n");
diff --git a/converters/fsio/fsio-rt11.1 b/converters/fsio/fsio-rt11.1
index 923d9c7..2dce4a0 100644
--- a/converters/fsio/fsio-rt11.1
+++ b/converters/fsio/fsio-rt11.1
@@ -49,6 +49,12 @@ depending on the type of device specified:
 .br
 .RS
 .TP
+\fIrk05\fP    \- RK05 image (2.5MB, 4800 blocks)
+.br
+.TP
+\fIrl01\fP    \- RL01 image (5MB, 10240 blocks)
+.br
+.TP
 \fIrl02\fP    \- RL02 image (10MB, 20480 blocks)
 .br
 .TP
diff --git a/converters/fsio/fsio.c b/converters/fsio/fsio.c
index 116a5c1..57017a4 100644
--- a/converters/fsio/fsio.c
+++ b/converters/fsio/fsio.c
@@ -356,6 +356,46 @@ struct mountedFS *mounts;
 
 struct FSdef *fileSystems = NULL;
 
+/*
+ * Tables for use with bitmap allocators
+ */
+uint16_t bits[16] = {
+  0000001, 0000002, 0000004, 0000010, 0000020, 0000040, 0000100, 0000200,
+  0000400, 0001000, 0002000, 0004000, 0010000, 0020000, 0040000, 0100000
+};
+
+uint16_t lowbits[16] = {
+  0000001, 0000003, 0000007, 0000017, 0000037, 0000077, 0000177, 0000377,
+  0000777, 0001777, 0003777, 0007777, 0017777, 0037777, 0077777, 0177777
+};
+
+uint16_t highbits[16] = {
+  0100000, 0140000, 0160000, 0170000, 0174000, 0176000, 0177000, 0177400,
+  0177600, 0177700, 0177740, 0177760, 0177770, 0177774, 0177776, 0177777
+};
+
+/*
+ * Table of # of zeroes in each byte value.
+ */
+uint8_t zeroes[256] = {
+  8,  7,  7,  6,  7,  6,  6,  5,  7,  6,  6,  5,  6,  5,  5,  4,
+  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
+  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
+  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
+  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
+  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
+  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
+  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
+  7,  6,  6,  5,  6,  5,  5,  4,  6,  5,  5,  4,  5,  4,  4,  3,
+  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
+  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
+  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
+  6,  5,  5,  4,  5,  4,  4,  3,  5,  4,  4,  3,  4,  3,  3,  2,
+  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
+  5,  4,  4,  3,  4,  3,  3,  2,  4,  3,  3,  2,  3,  2,  2,  1,
+  4,  3,  3,  2,  3,  2,  2,  1,  3,  2,  2,  1,  2,  1,  1,  0,
+};
+
 void FSioCommands(FILE *);
 static void FSioExecute(char *);
 
@@ -1926,6 +1966,77 @@ void FSioCommands(
 #endif
 }
 
+/*++
+ *      F S i o R e a d B l o b
+ *
+ *  Read an arbitrary sized blob of binary data from the container file. The
+ *  caller is responsible for making sure that the buffer has sufficient
+ *  space for the blob.
+ *
+ * Inputs:
+ *
+ *      mount           - pointer to a mounted file system descriptor
+ *      offset          - offset in the container file to start the read
+ *      size            - size of the data to read (in bytes)
+ *      buf             - pointer to the buffer to receive the data
+ *
+ * Outputs:
+ *
+ *      The buffer will be overwrittn by the contents of the blob from the
+ *      container file system
+ *
+ * Returns:
+ *
+ *      1 if read was successful, 0 otherwise
+ *
+ --*/
+int FSioReadBlob(
+  struct mountedFS *mount,
+  off_t offset,
+  unsigned int size,
+  void *buf
+)
+{
+  if (fseeko(mount->container, offset, SEEK_SET) == 0)
+    return fread(buf, size, 1, mount->container);
+
+  return 0;
+}
+
+/*++
+ *      F S i o W r i t e B l o b
+ *
+ *  Write an arbitrary sized blob of binary to from the container file.
+ *
+ * Inputs:
+ *
+ *      mount           - pointer to a mounted file system descriptor
+ *      offset          - offset in the container file to start the write
+ *      size            - size of the data to write (in bytes)
+ *      buf             - pointer to the buffer with the data
+ *
+ * Outputs:
+ *
+ *      None
+ *
+ * Returns:
+ *
+ *      1 if write was successful, 0 otherwise
+ *
+ --*/
+int FSioWriteBlob(
+  struct mountedFS *mount,
+  off_t offset,
+  unsigned int size,
+  void *buf
+)
+{
+  if (fseeko(mount->container, offset, SEEK_SET) == 0)
+    return fwrite(buf, size, 1, mount->container);
+
+  return 0;
+}
+
 /*++
  *      F S i o R e a d B l o c k
  *
@@ -2049,7 +2160,7 @@ int FSioReadSector(
  *      mount           - pointer to a mounted file system descriptor
  *      sector          - logical sector # in the range 0 - N
  *      size            - size of each sector (in bytes)
- *      buf             - pointer to the buffer to receive the data
+ *      buf             - pointer to the buffer with the data
  *
  * Outputs:
  *
@@ -2057,7 +2168,7 @@ int FSioReadSector(
  *
  * Returns:
  *
- *      1 if read was successful, 0 otherwise
+ *      1 if write was successful, 0 otherwise
  *
  --*/
 int FSioWriteSector(
diff --git a/converters/fsio/fsio.h b/converters/fsio/fsio.h
index 02c86d5..c9f1d60 100644
--- a/converters/fsio/fsio.h
+++ b/converters/fsio/fsio.h
@@ -164,6 +164,8 @@ struct mountedFS {
 #define os8data         FSdata._os8
 };
 
+extern int FSioReadBlob(struct mountedFS *, off_t, unsigned int, void *);
+extern int FSioWriteBlob(struct mountedFS *, off_t, unsigned int, void *);
 extern int FSioReadBlock(struct mountedFS *, unsigned int, void *);
 extern int FSioWriteBlock(struct mountedFS *, unsigned int, void *);
 extern int FSioReadSector(struct mountedFS *, unsigned int, unsigned int, void *);
diff --git a/converters/fsio/os8.c b/converters/fsio/os8.c
index bebcf33..8e705b7 100644
--- a/converters/fsio/os8.c
+++ b/converters/fsio/os8.c
@@ -1023,11 +1023,10 @@ static int os8CheckDirectory(
 )
 {
   struct OS8data *data = &mount->os8data;
-  uint16_t i, entrysz, entries, extra, off = OS8_DH_SIZE;
+  uint16_t i, entrysz, entries, off = OS8_DH_SIZE;
 
   entrysz = OS8_DI_SIZE + (-os8SXT(le16toh(data->buf[OS8_DH_EXTRA])));
   entries = os8Neg(le16toh(data->buf[OS8_DH_ENTRIES]));
-  extra = os8Neg(le16toh(data->buf[OS8_DH_EXTRA]));
 
   for (i = 0; i < entries; i++)
     if (os8Word(le16toh(data->buf[off + OS8_DI_FNAME1])) != 0)
@@ -1116,11 +1115,11 @@ static int os8FindSpace(
                 }
           }
           off += OS8_ED_SIZE;
-          } else {
-            blks = os8Neg(le16toh(data->buf[off + extra + OS8_DI_LENGTH]));
-            off += entrysz;
-          }
-          startblk += blks;
+        } else {
+          blks = os8Neg(le16toh(data->buf[off + extra + OS8_DI_LENGTH]));
+          off += entrysz;
+        }
+        startblk += blks;
       }
 
       dirblk = os8Word(le16toh(data->buf[OS8_DH_NEXT]));
@@ -2991,7 +2990,7 @@ static size_t os8WriteFile(
 struct FSdef os8FS = {
   NULL,
   "os8",
-  "os8              PDP-8 OS/8 file system\n",
+  "os8              PDP-8 OS/8 file system (RX01, RX02 or RK05 disks)\n",
   FS_UNITVALID,
   OS8_BLOCKSIZE * sizeof(uint16_t),
   os8Mount,
diff --git a/converters/fsio/rt11.c b/converters/fsio/rt11.c
index fb105e9..94c1e48 100644
--- a/converters/fsio/rt11.c
+++ b/converters/fsio/rt11.c
@@ -45,6 +45,8 @@ static struct DiskSize {
   char          *name;                  /* Disk name */
   size_t        size;                   /* Disk size */
 } rt11DiskSize[] = {
+  { "rk05", RT11_RK05SZ * RT11_BLOCKSIZE },
+  { "rl01", RT11_RL01SZ * RT11_BLOCKSIZE },
   { "rl02", RT11_RL02SZ * RT11_BLOCKSIZE },
   { "rx01", RT11_RX0xSZ * RT11_RX01SS },
   { "rx02", RT11_RX0xSZ * RT11_RX02SS },
@@ -1483,7 +1485,7 @@ static int partitionType(
  *
  *      mount           - pointer to a mounted file system descriptor
  *      unit            - partition number
- *      blocks          - return the actual size of the partition here
+ *      maxblk          - return maximum block # of the partition here
  *      first           - return first directory segment block # here
  *
  * Outputs:
@@ -1502,7 +1504,7 @@ static int partitionType(
 static int validate(
   struct mountedFS *mount,
   uint8_t unit,
-  uint16_t *blocks,
+  uint16_t *maxblk,
   uint16_t *first
 )
 {
@@ -1561,6 +1563,8 @@ static int validate(
            ((RT11_DS_SIZE - off) >= entrysz)) {
       uint16_t status = le16toh(data->buf[off + RT11_DI_STATUS]);
 
+      position += le16toh(data->buf[off + RT11_DI_LENGTH]);
+
       if ((status & RT11_E_MPTY) != 0)
         break;
 
@@ -1571,8 +1575,6 @@ static int validate(
       if (((position + le16toh(data->buf[off + RT11_DI_LENGTH])) & 0xFFFF) < position)
         return RT11_NOPART;
 
-      position += le16toh(data->buf[off + RT11_DI_LENGTH]);
-
       off += entrysz;
     }
     if (position > highest)
@@ -1584,7 +1586,7 @@ static int validate(
       return RT11_NOPART;
    } while (dsseg != 0);
 
-  *blocks = highest;
+  *maxblk = highest - 1;
   return type;
 }
 
@@ -1936,7 +1938,7 @@ static void rt11Umount(
  *
  * Returns:
  *
- *      Size of the container file in blocks of default file system size
+ *      Size of the container file in bytes.
  *
  --*/
 static size_t rt11Size(void)
@@ -1970,7 +1972,7 @@ static size_t rt11Size(void)
  *
  *      mount           - pointer to a mounted file system descriptor
  *                        (not in the mounted file system list)
- *      size            - the size (in blocks) of the file system
+ *      size            - the size (in bytes) of the file system
  *
  * Outputs:
  *
@@ -2024,7 +2026,8 @@ static int rt11Newfs(
   /*
    * Remove possible first track
    */
-  size = ((size * RT11_BLOCKSIZE) - mount->skip) / RT11_BLOCKSIZE;
+  size = (size - mount->skip) / RT11_BLOCKSIZE;
+  //  size = ((size * RT11_BLOCKSIZE) - mount->skip) / RT11_BLOCKSIZE;
 
   /*
    * Mark partition 0 as valid
@@ -2038,14 +2041,15 @@ static int rt11Newfs(
   /*
    * Build and write the Home Block.
    */
-  memset(data->buf, 0, RT11_BLOCKSIZE);
+  memset(&data->buf[0], 0, RT11_BLOCKSIZE);
 
   data->buf[RT11_HB_PCS] = htole16(1);
   data->buf[RT11_HB_FIRST] = htole16(RT11_DSSTART);
   data->buf[RT11_HB_SYSVER] = htole16(RT11_SYSVER_V05);
-  strncpy((char *)&data->buf[RT11_HB_VOLID], RT11_VOLID, strlen(RT11_VOLID));
-  strncpy((char *)&data->buf[RT11_HB_OWNER], RT11_OWNER, strlen(RT11_OWNER));
-  strncpy((char *)&data->buf[RT11_HB_SYSID], RT11_SYSID, strlen(RT11_SYSID));
+
+  memcpy((char *)&data->buf[RT11_HB_VOLID], RT11_VOLID, strlen(RT11_VOLID));
+  memcpy((char *)&data->buf[RT11_HB_OWNER], RT11_OWNER, strlen(RT11_OWNER));
+  memcpy((char *)&data->buf[RT11_HB_SYSID], RT11_SYSID, strlen(RT11_SYSID));
 
   for (i = 0; i < 255; i++)
     checksum += le16toh(data->buf[i]);
diff --git a/converters/fsio/rt11.h b/converters/fsio/rt11.h
index 6159576..378485a 100644
--- a/converters/fsio/rt11.h
+++ b/converters/fsio/rt11.h
@@ -191,6 +191,8 @@
 #define RT11_MAXPARTSZ  0200000         /* Max partition size */
 #define RT11_MINPARTSZ  0000010         /* Min partition size */
 
+#define RT11_RK05SZ     4800            /* Blocks on an RK05 drive */
+#define RT11_RL01SZ     10240           /* Blocks on an RL01 drive */
 #define RT11_RL02SZ     20480           /* Blocks on an RL02 drive */
 #define RT11_RX0xSZ     2002            /* Sectors on an RX01/RX02 */