diff --git a/sys/src/boot/pc/fat.c b/sys/src/boot/pc/fat.c
index 285a08594..a35d4b043 100644
--- a/sys/src/boot/pc/fat.c
+++ b/sys/src/boot/pc/fat.c
@@ -1,20 +1,42 @@
 #include <u.h>
 #include "fns.h"
 
+#define GETSHORT(p) (*(ushort *)(p))
+#define GETLONG(p) (*(uint *)(p))
+
 enum {
 	Sectsz = 0x200,
 	Dirsz = 0x20,
 	Maxpath = 64,
+	Fat12 = 1,
+	Fat16 = 2,
+	Fat32 = 4,
 };
 
 typedef struct Extend Extend;
 typedef struct Dir Dir;
 typedef struct Pbs Pbs;
+typedef struct Fat Fat;
+
+struct Fat
+{
+	ulong ver;
+	int drive;
+	ulong clustsize;
+	ulong eofmark;
+	ulong partlba;
+	ulong fatlba;
+	ulong dirstart; /* LBA for FAT16, cluster for FAT32 */
+	ulong dirents;
+	ulong datalba;
+};
 
 struct Extend
 {
-	int drive;
+	Fat *fat;
 	ulong lba;
+	ulong clust;
+	ulong lbaoff;
 	ulong len;
 	uchar *rp;
 	uchar *ep;
@@ -53,12 +75,34 @@ struct Pbs
 	uchar nheads[2];
 	uchar nhidden[4];
 	uchar bigvolsize[4];
-	uchar driveno;
-	uchar reserved0;
-	uchar bootsig;
-	uchar volid[4];
-	uchar label[11];
-	uchar type[8];
+	union
+	{
+		struct
+		{
+			uchar driveno;
+			uchar reserved0;
+			uchar bootsig;
+			uchar volid[4];
+			uchar label[11];
+			uchar type[8];
+		} fat16;
+		struct
+		{
+			uchar fatsize[4];
+			uchar flags[2];
+			uchar ver[2];
+			uchar rootclust[4];
+			uchar fsinfo[2];
+			uchar bootbak[2];
+			uchar reserved0[12];
+			uchar driveno;
+			uchar reserved1;
+			uchar bootsig;
+			uchar volid[4];
+			uchar label[11];
+			uchar type[8];
+		} fat32;
+	};
 };
 
 int readsect(ulong drive, ulong lba, void *buf);
@@ -68,14 +112,47 @@ unload(void)
 {
 }
 
+static ulong
+readnext(Extend *ex, ulong clust)
+{
+	Fat *fat = ex->fat;
+	uint b = fat->ver;
+	ulong sect, off;
+	
+	sect = clust * b / Sectsz;
+	off = clust * b % Sectsz;
+	if(readsect(fat->drive, fat->fatlba + sect, ex->buf))
+		memset(ex->buf, 0xff, 4);
+	switch(fat->ver){
+	case Fat16:
+		return GETSHORT(&ex->buf[off]);
+	case Fat32:
+		return GETLONG(&ex->buf[off])& 0x0fffffff;
+	}
+	return 0;
+}
+
 int
 read(void *f, void *data, int len)
 {
 	Extend *ex = f;
+	Fat *fat = ex->fat;
 
-	if(ex->len > 0 && ex->rp >= ex->ep)
-		if(readsect(ex->drive, ex->lba++, ex->rp = ex->buf))
+	if(ex->len > 0 && ex->rp >= ex->ep){
+		if(ex->clust != ~0U){
+			if(ex->lbaoff % fat->clustsize == 0){
+				if((ex->clust >> 4) == fat->eofmark)
+					return -1;
+				ex->lbaoff = (ex->clust - 2) * fat->clustsize;
+				putc('.');
+				ex->clust = readnext(ex, ex->clust);
+				ex->lba = ex->lbaoff + fat->datalba;
+			}
+			ex->lbaoff++;
+		}
+		if(readsect(fat->drive, ex->lba++, ex->rp = ex->buf))
 			return -1;
+	}
 	if(ex->len < len)
 		len = ex->len;
 	if(len > (ex->ep - ex->rp))
@@ -87,42 +164,21 @@ read(void *f, void *data, int len)
 }
 
 void
-close(void *f)
+open(Fat *fat, void *f, ulong lba)
 {
 	Extend *ex = f;
 
-	ex->drive = 0;
-	ex->lba = 0;
+	ex->fat = fat;
+	ex->lba = lba;
 	ex->len = 0;
+	ex->lbaoff = 0;
+	ex->clust = ~0U;
 	ex->rp = ex->ep = ex->buf + Sectsz;
 }
 
-static ulong
-rootlba(Extend *fat)
+void
+close(void *)
 {
-	ulong lba;
-	Pbs *p = (Pbs*)fat->buf;
-
-	lba = fat->lba;
-	lba += *((ushort*)p->nreserv);
-	lba += *((ushort*)p->fatsize) * p->nfats;
-	return lba;
-}
-
-static ulong
-dirlba(Extend *fat, Dir *d)
-{
-	ulong clust;
-	ulong dirs;
-	ulong lba;
-	Pbs *p = (Pbs*)fat->buf;
-
-	lba = rootlba(fat);
-	dirs = *((ushort*)p->rootsize);
-	lba += (dirs * Dirsz + Sectsz-1) / Sectsz;
-	clust = *((ushort*)d->starthi)<<16 | *((ushort*)d->startlo);
-	lba += (clust - 2) * p->clustsize;
-	return lba;
 }
 
 static int
@@ -155,18 +211,27 @@ dirname(Dir *d, char buf[Maxpath])
 	return x - buf;
 }
 
+static ulong
+dirclust(Dir *d)
+{
+	return *((ushort*)d->starthi)<<16 | *((ushort*)d->startlo);
+}
+
 static int
-fatwalk(Extend *ex, Extend *fat, char *path)
+fatwalk(Extend *ex, Fat *fat, char *path)
 {
 	char name[Maxpath], *end;
-	Pbs *pbs = (Pbs*)fat->buf;
 	int i, j;
 	Dir d;
 
-	close(ex);
-	ex->drive = fat->drive;
-	ex->lba = rootlba(fat);
-	ex->len = *((ushort*)pbs->rootsize) * Dirsz;
+	if(fat->ver == Fat32){
+		open(fat, ex, 0);
+		ex->clust = fat->dirstart;
+		ex->len = ~0U;
+	}else{
+		open(fat, ex, fat->dirstart);
+		ex->len = fat->dirents * Dirsz;
+	}
 	for(;;){
 		if(readn(ex, &d, Dirsz) != Dirsz)
 			break;
@@ -178,25 +243,81 @@ fatwalk(Extend *ex, Extend *fat, char *path)
 			end = path + strlen(path);
 		j = end - path;
 		if(i == j && memcmp(name, path, j) == 0){
-			ex->rp = ex->ep;
-			ex->lba = dirlba(fat, &d);
+			open(fat, ex, 0);
+			ex->clust = dirclust(&d);
 			ex->len = *((ulong*)d.len);
 			if(*end == 0)
 				return 0;
 			else if(d.attr & 0x10){
-				ex->len = pbs->clustsize * Sectsz;
+				ex->len = fat->clustsize * Sectsz;
 				path = end;
 				continue;
 			}
 			break;
 		}
 	}
-	close(ex);
 	return -1;
 }
 
 static int
-findfat(Extend *fat, int drive)
+conffat(Fat *fat, void *buf)
+{
+	Pbs *p = buf;
+	uint fatsize, volsize, datasize, reserved;
+	uint ver, dirsize, dirents, clusters;
+	
+	/* sanity check */
+	if(GETSHORT(p->sectsize) != Sectsz){
+		print("sectsize != 512\r\n");
+		halt();
+	}
+	
+	/* load values from fat */
+	fatsize = GETSHORT(p->fatsize);
+	if(fatsize == 0)
+		fatsize = GETLONG(p->fat32.fatsize);
+	volsize = GETSHORT(p->volsize);
+	if(volsize == 0)
+		volsize = GETLONG(p->bigvolsize);
+	reserved = GETSHORT(p->nreserv);
+	dirents = GETSHORT(p->rootsize);
+	dirsize = (dirents * Dirsz + Sectsz - 1) / Sectsz;
+	datasize = volsize - (reserved + fatsize * p->nfats + dirsize);
+	clusters = datasize / p->clustsize;
+	
+	/* determine fat type */
+	if(clusters < 4085)
+		ver = Fat12;
+	else if(clusters < 65525)
+		ver = Fat16;
+	else
+		ver = Fat32;
+	
+	/* another check */
+	if(ver == Fat12){
+		print("TODO: implement FAT12\r\n");
+		halt();
+	}
+	
+	/* fill FAT descriptor */
+	fat->ver = ver;
+	fat->dirents = dirents;
+	fat->clustsize = p->clustsize;
+	fat->fatlba = fat->partlba + reserved;
+	fat->dirstart  = fat->fatlba + fatsize * p->nfats;
+	if(ver == Fat32){
+		fat->datalba = fat->dirstart;
+		fat->dirstart  = GETLONG(p->fat32.rootclust);
+		fat->eofmark = 0xffffff;
+	}else{
+		fat->datalba = fat->dirstart + dirsize;
+		fat->eofmark = 0xfff;
+	}	
+	return 0;
+}
+
+static int
+findfat(Fat *fat, int drive)
 {
 	struct {
 		uchar status;
@@ -206,20 +327,22 @@ findfat(Extend *fat, int drive)
 		uchar lba[4];
 		uchar len[4];
 	} *p;
+	uchar buf[Sectsz];
 	int i;
 
-	if(readsect(drive, 0, fat->buf))
+	if(readsect(drive, 0, buf))
 		return -1;
-	if(fat->buf[0x1fe] != 0x55 || fat->buf[0x1ff] != 0xAA)
+	if(buf[0x1fe] != 0x55 || buf[0x1ff] != 0xAA)
 		return -1;
-	p = (void*)&fat->buf[0x1be];
+	p = (void*)&buf[0x1be];
 	for(i=0; i<4; i++){
 		if(p[i].status != 0x80)
 			continue;
-		close(fat);
 		fat->drive = drive;
-		fat->lba = *((ulong*)p[i].lba);
-		if(readsect(drive, fat->lba, fat->buf))
+		fat->partlba = *((ulong*)p[i].lba);
+		if(readsect(drive, fat->partlba, buf))
+			continue;
+		if(conffat(fat, buf))
 			continue;
 		return 0;
 	}
@@ -231,12 +354,14 @@ start(void *sp)
 {
 	char path[Maxpath], *kern;
 	int drive;
-	Extend fat, ex;
+	Extend ex;
+	Fat fat;
 	void *f;
 
 	/* drive passed in DL */
 	drive = ((ushort*)sp)[5] & 0xFF;
 
+	print("9bootfat\r\n");
 	if(findfat(&fat, drive)){
 		print("no fat\r\n");
 		halt();