diff --git a/src/sys/ubixfsv2/ubixfs.cpp b/src/sys/ubixfsv2/ubixfs.cpp
index 0dbe748..a72d4ec 100644
--- a/src/sys/ubixfsv2/ubixfs.cpp
+++ b/src/sys/ubixfsv2/ubixfs.cpp
@@ -1,4 +1,5 @@
 #include <stddef.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <assert.h>
@@ -191,6 +192,7 @@
   ubixfsInode * inode = NULL;
 
   inode = new ubixfsInode;
+  assert(inode);
   if (inode == NULL) return NULL;
   memset(inode, 0, sizeof(ubixfsInode));
 
@@ -253,7 +255,7 @@
   if (sb == NULL) return -1;
   memset(sb, 0, sizeof(diskSuperBlock));
 
-  // dev->size is the size of the device in 512 sectors
+  // dev->size is the size of the device in 512 byte sectors
 
   blocks = (dev->size-1) / 8;     // 4k blocks
   batSize = (dev->size-1) % 8;    // remainder
@@ -283,6 +285,9 @@
   sb->numAGs = (sb->numBlocks+2047) / 2048;
   sb->lastUsedAG = 0;
 
+  // the BAT exists outside our official block count, so no 
+  // entries in the BAT need to be set for it
+
   sb->BAT.allocationGroup = batSect / sb->blocksPerAG;
   sb->BAT.start = batSect % sb->blocksPerAG;
   sb->BAT.len = (batSize+7) / 8;
@@ -298,11 +303,43 @@
   sb->indicies.start = 0;
   sb->indicies.len = 0;
 
-  sb->rootDir.allocationGroup = 2;
+  sb->rootDir.allocationGroup = 0;
   sb->rootDir.start = 0;
   sb->rootDir.len = 1;
 
+  // write out the superBlock
   dev->write(dev, sb, dev->size-1, 1);
+ 
+  // mark the first two 4k blocks used
+  sector[0] = (1 << 7) | (1 << 6);
+  // write out the first sector of the BAT 
+  dev->write(dev, &sector, batSect, 1);
+  // clear the rest
+  sector[0] = 0;
+  // write out the rest of the BAT
+  dev->write(dev, &sector, batSect+1, batSize-1);
+
+  /* allocate part of the root dir */
+
+  // sanity checks
+  assert(superBlock->blockSize);
+  assert((unsigned)superBlock->blockSize >= sizeof(bTreeHeader));
+
+  bTreeHeader * bth = (bTreeHeader *)malloc(superBlock->blockSize);
+  assert(bth);
+  memset(bth, 0, superBlock->blockSize);
+  bth->firstDeleted = bth->firstNodeOffset = -1;
+
+  // write out the "root" dir inode
+  ubixfsInode * inode = new ubixfsInode;
+  assert(inode);
+  memset(inode, 0, sizeof(ubixfsInode));
+
+  strcpy(inode->name, "/");
+  dev->write(dev, inode, 0, superBlock->inodeSize / 512);
+  // write out the "root" dir
+  dev->write(dev, bth, 1, superBlock->blockSize / 512);
+  free(bth);
   delete sb;
   return 0;
 } // UbixFS::vfs_format