Block 0			BOOT1 - Bootstrap - Load OS from blocks 1-16 to pages 1-17 (mem 0400-7777)
Block 1 - 16		Operating System
Block 17			LYOUT - Disk layout information
Block 18 - n		DIREC - Disk directories
Block n+1 - end		DATAB - Data blocks/File Table disk-mapping/
				File header Block

LYOUT Block:
Byte		Data		Description
=========	=============   =====================================
  1 -   8 	DISKID		8-byte ASCII Disk Label
  9 -  14	FMTID		6-byte literal 'POSDSK' to identify
				a valid drive
 15 -  15	unused
 16		SECSIZ		Binary - Sector Size of drive
 17		SECTRK		Binary - Sectors per track
 18		TRKHD		Binary - Tracks per head
 19		HDDRV		Binary - Heads per drive
 20		BOOTS		Binary - Start sector of OS
 21		BOOTT		Binary - Start track of OS
 22		BOOTH		Binary - Start head of OS
 23 -  24	BOOTM		Binary - Start address to load OS
 25 - 256	unused

DATAB Block:
Byte		Data		Description
=========	=============   =====================================
  1 - 256	DATA		File Data

DIREC Block:
Byte		Data		Description
=============	=============   =====================================
1		BLKTYP		Literal "D" -- Directory block

N+2   - N+9	FILNAM		File Name
N+10  - N+12	FILTYP		File type
N+13  - N+14	FILBLK		Number of blocks used
N+15  - N+16	FILTD		Number of directory blocks used
N+17  - N+18	FILTAB1		First data-mapping block location
N+19  - N+20	FSIZE		File size in words
N+21  - N+21	FUID		File owner's UID
N+22  - N+71	FTITLE		File title text
   (15 more entries)

Byte		Data		Description
=============	=============   =====================================
1		BLKTYP		Literal "M" -- Data mapping block
2     -    3	DMBP		Previous data mapping block (or 0)
4     -    4	

Byte		Data		Description
=============	=============   =====================================
1		BLKTYP		Literal "H" -- File header block
2     -    2	FUID		File owner's UID
3     -    4	FSIZE		File size in words
5     -   34	FTITLE		File title text

--------------------------------------------
1.6 million 12-bit words

Data Tracks 		203
Surfaces 		2
Sectors per track 	16
Words per sector 	256 (4096 per track)