diff --git a/fat32lib/TODO b/fat32lib/TODO
index 322b91d..35d4d0a 100644
--- a/fat32lib/TODO
+++ b/fat32lib/TODO
@@ -1,13 +1,14 @@
-newlog naming template, 3 for extension, else max, [0-9A-Z], so FFFFFFFF would do hex, 99999999 would do decimal, ZZZZZZZZ would do all, "FFFF    " would limit to 4 chars.
-
-New cluster and link cluster should only do one read then write instead of r w r w.
+(TESTING) New cluster and link cluster should only do one read then write instead of r w r w.
 dirty buffer flag for RMW - write only when needed, validate RMW fully/properly
+Double buffer for sector (fill one while pulling from other).
 typedef int to something?
 max file size - if using auto-create log, auto create next log
 
 if directory empty allow rmdir
    check for empty, save . and .. cluster num, delete dir as file, cd .., find . cluster, 0xe5 ent.
 
+newlog naming template, 3 for extension, else max, [0-9A-Z], so FFFFFFFF would do hex, 99999999 would do decimal, ZZZZZZZZ would do all, "FFFF    " would limit to 4 chars.
+
 rename (and/or move in tree) (technically writing the directory, chk for dup name)
 
 optional clear new linked clusters (takes time but log will be cleaner on crash
diff --git a/fat32lib/creat.c b/fat32lib/creat.c
index a1b430c..e642c51 100644
--- a/fat32lib/creat.c
+++ b/fat32lib/creat.c
@@ -3,8 +3,7 @@
 // sequence number for next auto log file name;
 static u32 nextlog = 0;
 
-unsigned char fntemplate[10] = "FFFFFFFF";
-unsigned char extension[4] = "LOG";
+unsigned char newextension[4] = "LOG";
 
 static void clearclus(u32 clus)
 {
@@ -49,8 +48,7 @@ static int findemptydirent(u8 * dosname)
                 if (c[11] == 0x0f)      // long name ent
                     continue;
                 if (!dosname) {
-
-                    if (c[8] == extension[0] && c[9] == extension[1] && c[10] == extension[2]) {
+                    if (c[8] == newextension[0] && c[9] == newextension[1] && c[10] == newextension[2]) {
                         u32 thislog = 0;
                         u16 j, k;
                         for (j = 0; j < 8; j++) {
@@ -97,6 +95,43 @@ static void setdirent(u8 * c, u8 attr, u32 clus)
     }
 }
 
+static u32 getclus()
+{
+    u32 clus = 0, newclus, curr = 1;
+    u8 *c;
+
+    newclus = currclus + 1;
+    while (newclus < fpm.mxcl) {
+        readsec(fpm.fat0 + (newclus >> 7));     // read sector with cluster
+        clus = newclus & 127;   // index within sector
+        c = &filesectbuf[clus << 2];
+        do {
+            get4todw(curr);     // get linked cluster
+        } while (curr && ++clus < 128);
+        newclus &= ~127;
+        if (clus < 128)
+            break;
+        newclus += 128;
+    }
+    if (newclus >= fpm.mxcl)
+        return 0;
+    newclus += clus;
+    c = &filesectbuf[clus << 2];
+    *c++ = 0xff;
+    *c++ = 0xff;
+    *c++ = 0xff;
+    *c = 0x0f;
+    // can merge link here for that case - saves extra read and write if in same clus
+    u8 i;
+    for (i = 0; i < fpm.nft; i++)
+        writesec(fpm.fat0 + (newclus >> 7) + i * fpm.spf);
+
+    secinclus = 0;
+    byteinsec = 0;
+
+    return newclus;
+}
+
 int newdirent(u8 * dosname, u8 attr)
 {
     int r;
@@ -122,7 +157,7 @@ int newdirent(u8 * dosname, u8 attr)
         u32 t = nextlog;
         u8 i = 8, j;
         c += 8;
-        tzmemcpy(c, extension, 3);
+        tzmemcpy(c, newextension, 3);
         while (i--) {
             j = t & 15;
 #ifndef HEXFN
diff --git a/fat32lib/fat32.h b/fat32lib/fat32.h
index e954531..7f582f7 100644
--- a/fat32lib/fat32.h
+++ b/fat32lib/fat32.h
@@ -42,8 +42,7 @@ int getdirent(u8 * dosmatch);
 // creates new file or directory (attr with 0x10 set) - changes to dir or ready to write if xero return
 // combined creat / mkdir
 // if dosname is NULL (a null pointer) it creates %08X.LOG where the number is 1 greater than any existing
-unsigned char extension[4]; //= "LOG";
-unsigned char fntemplate[10]; //= "FFFFFFFF";
+unsigned char newextension[4]; //= "LOG";
 int newdirent(u8 * dosname, u8 attr);
 
 // WRITE
@@ -58,6 +57,7 @@ int writenextsect(void);        // writes entire secbuf, links, continues at nex
 // write out partially written sector
 void flushbuf(void);
 
+// DO flushbuf BEFORE CALLING THIS IF THE BUFFER IS NOT FLUSHED
 // update dirent for writes - mainly file size if changed.past EOF.
 // Maxout extends to end of cluster for crash recovery - won't miss anything
 void syncdirent(u8 maxout);
diff --git a/fat32lib/fat32private.h b/fat32lib/fat32private.h
index 867baad..9d78aab 100644
--- a/fat32lib/fat32private.h
+++ b/fat32lib/fat32private.h
@@ -62,7 +62,6 @@ FAT32EXTERN u16 byteinsec;      //which byte in the sector
 FAT32EXTERN u8 rmw;             // read-mod-write mode, off after new file, append, and truncate
 
 u32 nextclus(u32 clus);
-u32 getclus(void);
 
 // ATTR X X ARCH DIR VOLID SYS HID RO
 // DATE Y-1980, 7 bits : Month 1-12 J=1, 4 bits, Day, 5 bits, 1-31
diff --git a/fat32lib/opendir.c b/fat32lib/opendir.c
index a9510da..f5a6894 100644
--- a/fat32lib/opendir.c
+++ b/fat32lib/opendir.c
@@ -38,6 +38,8 @@ int getdirent(u8 * dosmatch)
                 entcnt++;       // count entries
                 //               printf( ">%11.11s\n", c );
                 if (!tzfncmp(c, dosmatch)) {
+                    // RENAME HERE, memcpy 11 (or 3 for EXT) and writesec(thissector)
+
                     // check attributes, etc.
                     u16 chf;
                     c += 20;
diff --git a/fat32lib/write.c b/fat32lib/write.c
index 57bc2bd..1a62691 100644
--- a/fat32lib/write.c
+++ b/fat32lib/write.c
@@ -30,69 +30,71 @@ void syncdirent(u8 maxout)
     writesec(direntsect);
 }
 
-u32 getclus()
+// this allocates and links in a new cluseter.
+// inlined getclus so for in-sector, it iw r w(w fat copy 2) except where the link crosses sectors
+// whire it is r0 ... rN wN(wN) r0 w0(w0).
+static int linkclus()
 {
-    u32 clus = 0, newclus, curr = 1;
+    u32 nextc;
+    u32 clus = 0, curr = 1;
+    u32 cfatoffst, nfatoffst;
     u8 *c;
+    u8 i;
+
+    nextc = nextclus(currclus);
+    if (nextc < 0xffffff0)
+        return 0;
 
-    newclus = currclus + 1;
-    while (newclus < fpm.mxcl) {
-        readsec(fpm.fat0 + (newclus >> 7));     // read sector with cluster
-        clus = newclus & 127;   // index within sector
+    // from nextclus
+    cfatoffst = currclus >> 7;
+
+    nextc = currclus + 1;
+    while (nextc < fpm.mxcl) {
+        nfatoffst = nextc >> 7;
+        if( nfatoffst != cfatoffst ) {
+            readsec(fpm.fat0 + (nextc >> 7));     // read sector with cluster
+            cfatoffst = nfatoffst;
+        }
+        clus = nextc & 127;   // index within sector
         c = &filesectbuf[clus << 2];
         do {
             get4todw(curr);     // get linked cluster
         } while (curr && ++clus < 128);
-        newclus &= ~127;
+        nextc &= ~127;
         if (clus < 128)
             break;
-        newclus += 128;
+        nextc += 128;
     }
-    if (newclus >= fpm.mxcl)
-        return 0;
-    newclus += clus;
+    if (nextc >= fpm.mxcl) {
+        currclus = 0;
+        return -1;
+    }
+    nextc += clus;
     c = &filesectbuf[clus << 2];
     *c++ = 0xff;
     *c++ = 0xff;
     *c++ = 0xff;
     *c = 0x0f;
-    // can merge link here for that case - saves extra read and write if in same clus
-    u8 i;
-    for (i = 0; i < fpm.nft; i++)
-        writesec(fpm.fat0 + (newclus >> 7) + i * fpm.spf);
 
-    secinclus = 0;
-    byteinsec = 0;
-
-    return newclus;
-}
-
-static void linkclus()
-{
-    u32 nextc;
-
-    nextc = nextclus(currclus);
-    if (nextc < 0xffffff0)
-        return;
-
-    nextc = getclus();
-    if (!nextc) {
-        currclus = 0;
-        return;
+    cfatoffst = currclus >> 7;
+    if( cfatoffst != nfatoffst ) { // next clus is in diff FAT sector
+        for (i = 0; i < fpm.nft; i++)
+            writesec(fpm.fat0 + (nextc >> 7) + i * fpm.spf);
+        readsec(fpm.fat0 + cfatoffst);        // read sector with cluster
     }
-    // redundant if alloc and next are in same FAT sector
-    readsec(fpm.fat0 + (currclus >> 7));        // read sector with cluster
-    u8 *c = &filesectbuf[(currclus & 127) << 2];
+    c = &filesectbuf[(currclus & 127) << 2];
     // should be 0x0fffffff;
     *c++ = nextc;
     *c++ = nextc >> 8;
     *c++ = nextc >> 16;
     *c = nextc >> 24;
 
-    u8 i;
-    for (i = 0; i < fpm.nft; i++)
+    for (i = 0; i < fpm.nft; i++) // write the linked version out
         writesec(fpm.fat0 + (currclus >> 7) + i * fpm.spf);
     currclus = nextc;
+    secinclus = 0;
+    byteinsec = 0;
+    return 0;
 }
 
 void flushbuf()
@@ -130,7 +132,8 @@ int writenextsect()
 #if 0
         syncdirent(0);
 #endif
-        linkclus();
+        if( linkclus() )
+            return 1;
         secinclus = 0;
         if (currclus < 2)
             return 1;           // written, but no more space