diff --git a/utils/dos33fs-utils/dos33_vtoc_bitmap.c b/utils/dos33fs-utils/dos33_vtoc_bitmap.c
index b2348c71..ce9ffccd 100644
--- a/utils/dos33fs-utils/dos33_vtoc_bitmap.c
+++ b/utils/dos33fs-utils/dos33_vtoc_bitmap.c
@@ -2,6 +2,9 @@
 
 #include "dos33.h"
 
+/* FIXME: this code assumes that we have 16 sectors pretty much everywhere */
+
+
 static int ones_lookup[16]={
 	/* 0x0 = 0000 */ 0,
 	/* 0x1 = 0001 */ 1,
diff --git a/utils/dos33fs-utils/mkdos33fs.c b/utils/dos33fs-utils/mkdos33fs.c
index 30f5cce6..c47ad64d 100644
--- a/utils/dos33fs-utils/mkdos33fs.c
+++ b/utils/dos33fs-utils/mkdos33fs.c
@@ -32,12 +32,14 @@ static void usage(char *binary,int help) {
 
 int main(int argc, char **argv) {
 
-	int num_tracks=35,num_sectors=16,block_size=256;
+	int num_tracks=35,num_sectors=16,sector_size=256;
 	int max_files=105,catalog_track=17,vtoc_track=17,volume_number=254;
+	int catalog_sectors,current_sector;
 	int max_ts_pairs=255;
 	int fd,dos_fd;
 	char device[BUFSIZ],dos_src[BUFSIZ];
-	char *vtoc_buffer=NULL,*sector_buffer=NULL,*endptr;
+	unsigned char *vtoc_buffer=NULL,*sector_buffer=NULL;
+	char *endptr;
 	int i,c,copy_dos=0;
 	int result;
 
@@ -59,7 +61,7 @@ int main(int argc, char **argv) {
 				break;
 
 			case 'b':
-				block_size=strtol(optarg,&endptr,10);
+				sector_size=strtol(optarg,&endptr,10);
 				if ( endptr == optarg ) usage(argv[0], 1);
 				break;
 
@@ -98,35 +100,40 @@ int main(int argc, char **argv) {
 
 	strncpy(device,argv[optind],BUFSIZ-1);
 
+	/***********************/
 	/* Sanity check values */
+	/***********************/
 
-	/* s 2->32  (limited by 4-byte bitfields) */
+	/* sectors: 2->32  (limited by 4-byte bitfields) */
 	if ((num_sectors<2) || (num_sectors>32)) {
 		printf("Number of sectors must be >2 and <=32\n\n");
 		goto end_of_program;
 	}
 
-	/* t 1 ->(block_size-0x38)/2 */
-	if ((num_tracks<1) || (num_tracks>(block_size-0x38)/2)) {
-		printf("Number of tracks must be >18 and <=%i (block_size-0x38)/2\n\n",
-			(block_size-0x38)/2);
+	/* tracks 18-50 ->(sector_size-0x38)/4 */
+	/* limited by VTOC room for freespace bitmap (which is $38 to $ff) */
+	/* VOTC is always on track 17 so we need at least that many */
+	/* though could double if we used the unused sector fields */
+	if ((num_tracks<vtoc_track) || (num_tracks>(sector_size-0x38)/4)) {
+		printf("Number of tracks must be >%d and <=%i\n\n",
+			vtoc_track,(sector_size-0x38)/4);
 		goto end_of_program;
 	}
 
 	/* sector_size 256->65536 (or 512 based on one byte t/s size field?) */
-	if ((block_size<256)||(block_size>65536)) {
+	if ((sector_size<256)||(sector_size>65536)) {
 		printf("Block size must be >=256 and <65536\n\n");
 		goto end_of_program;
 	}
 
 	/* allocate space for buffers */
-	vtoc_buffer=calloc(1,sizeof(char)*block_size);
+	vtoc_buffer=calloc(1,sizeof(char)*sector_size);
 	if (vtoc_buffer==NULL) {
 		fprintf(stderr,"Error allocating memory!\n");
 		goto end_of_program;
 	}
 
-	sector_buffer=calloc(1,sizeof(char)*block_size);
+	sector_buffer=calloc(1,sizeof(char)*sector_size);
 	if (sector_buffer==NULL) {
 		fprintf(stderr,"Error allocating memory!\n");
 		goto end_of_program;
@@ -143,7 +150,7 @@ int main(int argc, char **argv) {
 
 	/* zero out file */
 	for(i=0;i<num_tracks*num_sectors;i++) {
-		result=write(fd,vtoc_buffer,block_size);
+		result=write(fd,vtoc_buffer,sector_size);
 	}
 
 	/**************************/
@@ -171,12 +178,19 @@ int main(int argc, char **argv) {
 			vtoc_track);
 	}
 
-	max_ts_pairs=((block_size-0xc)/2);
+	max_ts_pairs=((sector_size-0xc)/2);
 	if (max_ts_pairs>255) {
 		printf("Warning!  Truncating max_ts pairs to 255\n");
 		max_ts_pairs=255;
 	}
 
+	catalog_sectors=max_files/7;
+	if (max_files%7) catalog_sectors++;
+	if (catalog_sectors>num_sectors-1) {
+		printf("Warning! num_files leads to too many sectors %d, max is %d\n",catalog_sectors,num_sectors-1);
+		catalog_sectors=num_sectors-1;
+	}
+
 	/***************/
 	/* Create VTOC */
 	/***************/
@@ -193,7 +207,7 @@ int main(int argc, char **argv) {
 
 	/* Number of T/S pairs fitting */
 	/* in a T/S list sector */
-	/* Note, overflows if block_size>524 */
+	/* Note, overflows if sector_size>524 */
 	vtoc_buffer[VTOC_MAX_TS_PAIRS]=max_ts_pairs;
 
 	/* last track space was allocated on */
@@ -204,11 +218,11 @@ int main(int argc, char **argv) {
 
 	vtoc_buffer[VTOC_NUM_TRACKS]=num_tracks;
 	vtoc_buffer[VTOC_S_PER_TRACK]=num_sectors;
-	vtoc_buffer[VTOC_BYTES_PER_SL]=block_size&0xff;
-	vtoc_buffer[VTOC_BYTES_PER_SH]=(block_size>>8)&0xff;
+	vtoc_buffer[VTOC_BYTES_PER_SL]=sector_size&0xff;
+	vtoc_buffer[VTOC_BYTES_PER_SH]=(sector_size>>8)&0xff;
 
 	/* Set sector bitmap so whole disk is free */
-	for(i=VTOC_FREE_BITMAPS;i<block_size;i+=4) {
+	for(i=VTOC_FREE_BITMAPS;i<sector_size;i+=4) {
 		vtoc_buffer[i]=0xff;
 		vtoc_buffer[i+1]=0xff;
 		if (num_sectors>16) {
@@ -228,36 +242,26 @@ int main(int argc, char **argv) {
 		lseek(fd,0,SEEK_SET);
 		/* copy first 3 sectors */
 		for(i=0;i<3*(num_sectors);i++) {
-			result=read(dos_fd,vtoc_buffer,block_size);
-			result=write(fd,vtoc_buffer,block_size);
+			result=read(dos_fd,vtoc_buffer,sector_size);
+			result=write(fd,vtoc_buffer,sector_size);
 		}
 		close(dos_fd);
 
 		/* Set boot filename */
 
 		/* Track 1 sector 9 */
-		lseek(fd,((1*num_sectors)+9)*block_size,SEEK_SET);
-		result=read(fd,vtoc_buffer,block_size);
+		lseek(fd,((1*num_sectors)+9)*sector_size,SEEK_SET);
+		result=read(fd,vtoc_buffer,sector_size);
 
 		/* filename begins at offset 75 */
 		for(i=0;i<30;i++) {
 			vtoc_buffer[0x75+i]=boot_filename[i]|0x80;
 		}
-		lseek(fd,((1*num_sectors)+9)*block_size,SEEK_SET);
-		result=write(fd,vtoc_buffer,block_size);
-	}
+		lseek(fd,((1*num_sectors)+9)*sector_size,SEEK_SET);
+		result=write(fd,vtoc_buffer,sector_size);
 
+		/* if copying dos reserve tracks 1 and 2 as well */
 
-	/* reserve track 0 */
-	/* No user data can be stored here as track=0 is special case */
-	/* end of file indicator */
-	vtoc_buffer[VTOC_FREE_BITMAPS]=0x00;
-	vtoc_buffer[VTOC_FREE_BITMAPS+1]=0x00;
-	vtoc_buffer[VTOC_FREE_BITMAPS+2]=0x00;
-	vtoc_buffer[VTOC_FREE_BITMAPS+3]=0x00;
-
-	/* if copying dos reserve tracks 1 and 2 as well */
-	if (copy_dos) {
 		vtoc_buffer[VTOC_FREE_BITMAPS+4]=0x00;
 		vtoc_buffer[VTOC_FREE_BITMAPS+5]=0x00;
 		vtoc_buffer[VTOC_FREE_BITMAPS+6]=0x00;
@@ -266,36 +270,76 @@ int main(int argc, char **argv) {
 		vtoc_buffer[VTOC_FREE_BITMAPS+9]=0x00;
 		vtoc_buffer[VTOC_FREE_BITMAPS+10]=0x00;
 		vtoc_buffer[VTOC_FREE_BITMAPS+11]=0x00;
+
 	}
 
-	/* reserve track 17 (0x11) */
-	/* reserved for vtoc and catalog stuff */
-	vtoc_buffer[VTOC_FREE_BITMAPS+17*4]=0x00;
-	vtoc_buffer[VTOC_FREE_BITMAPS+17*4+1]=0x00;
-	vtoc_buffer[VTOC_FREE_BITMAPS+17*4+2]=0x00;
-	vtoc_buffer[VTOC_FREE_BITMAPS+17*4+3]=0x00;
+
+	/* reserve track 0 */
+	/* No user data can be stored here as track=0 is used */
+	/*   as a special-case end of file indicator */
+	for(i=0;i<num_sectors;i++) {
+		dos33_vtoc_reserve_sector(vtoc_buffer, 0, i);
+	}
+
+	/********************/
+	/* reserve the VTOC */
+	/********************/
+	dos33_vtoc_reserve_sector(vtoc_buffer, vtoc_track, 0);
+
+	/*****************/
+	/* Setup Catalog */
+	/*****************/
+
+	/* clear buffer */
+	memset(sector_buffer,0,sector_size);
+
+	/* Set catalog next pointers */
+	for(i=0;i<catalog_sectors;i++) {
+		/* point to next */
+		/* for first sector_size-1 walk backwards from T17S15 */
+		/* if more, allocate room on disk??? */
+		/* Max on 140k disk is 280 or so */
+
+		current_sector=num_sectors-i-1;
+
+		if (i==catalog_sectors-1) {
+			/* last one, pointer is to 0,0 */
+			sector_buffer[1]=0;
+			sector_buffer[2]=0;
+		}
+		else {
+			printf("Writing $%02X,$%02X=%d,%d\n",
+				catalog_track,current_sector,
+				catalog_track,current_sector-1);
+			sector_buffer[1]=catalog_track;
+			sector_buffer[2]=current_sector-1;
+		}
+
+		/* reserve */
+		dos33_vtoc_reserve_sector(vtoc_buffer,
+			catalog_track, current_sector);
+
+		lseek(fd,((catalog_track*num_sectors)+current_sector)*
+			sector_size,SEEK_SET);
+		result=write(fd,sector_buffer,sector_size);
+		if (result!=sector_size) {
+			fprintf(stderr,"Error writing catalog sector %d! (%s)\n",
+				current_sector,strerror(errno));
+
+		}
+	}
 
 	/**************************/
 	/* Write out VTOC to disk */
 	/**************************/
-	lseek(fd,((vtoc_track*num_sectors)+0)*block_size,SEEK_SET);
+	lseek(fd,((vtoc_track*num_sectors)+0)*sector_size,SEEK_SET);
 
-	result=write(fd,vtoc_buffer,block_size);
+	result=write(fd,vtoc_buffer,sector_size);
 	if (result<0) {
 		fprintf(stderr,"Error writing VTOC (%s)!\n",strerror(errno));
 	}
 
-	/* clear vtoc_buffer */
-	for(i=0;i<block_size;i++) vtoc_buffer[i]=0;
-	/* Set catalog next pointers */
-	for(i=(num_sectors-1);i>1;i--) {
-		vtoc_buffer[1]=0x11;
-		vtoc_buffer[2]=i-1;
 
-		lseek(fd,((17*num_sectors)+i)*block_size,SEEK_SET);
-		result=write(fd,vtoc_buffer,block_size);
-		if (result<0) fprintf(stderr,"Error writing!\n");
-	}
 
 	close(fd);