#FILE: $RCSfile: drgndos.txt $
#DESC: Dragon Dos Controller, Disk and File formats
#REV: $Revision: 1.4 $
#DATE: $Date: 1997/04/10 19:02:14 $
#AUTHOR: Graham E. Kinns
#DISCLAIMER: All information provided as is etc.
#ARCHIVE: This file is part of the DRGNINFO collection of Dragon info files
#CONTACT: Comments, bugs, revisions, suggestions to Dragon@grempc.demon.co.uk
#HISTORY: 1.0 16/03/94 - Initial version
#RCSID: $Id: drgndos.txt 1.4 1997/04/10 19:02:14 Graham Exp $
#XREF: basicfmt.txt - tokenised Basic format
#      tandydsk.txt - Tandy disk format

Contents:
=========

1.	Disk Controller Cartridge
2.	Dragon DOS variants
3.	Disk Layout
4.	Directory Track
5.	Bootable disks
6.	File extensions and formats
7.	Added BASIC Keywords by Token value
8.	Description of commands added to BASIC
9.	Programmers Guide to DragonDOS
10.	DOS Lower memory usage
11.	DOS Rom reference

1.  Disk Controller Cartridge
=============================

Chip used:	WD2797 (Upwardly compatible with 17xx series)
Memory Interface:
		Floppy Disc Controller Registers
	$ff40	Status Reg (Read) / Command Reg (Write)
	$ff41	Track Reg  (R/W)
	$ff42	Sector Reg (R/W)
	$ff43	Data Reg   (R/W)

	$ff48	Write-only data latch
		bit 7	Not used
		bit 6	Not used
		bit 5	Enables !NMI Interrupt from 2797 INTRQ
		bit 4	Enables write pre-compensation (Single Density only)
		bit 3	Single Density enable
		bit 2	Motor on
		bits1:0	Drive unit number 0 - 3

	NMI Interrupt from Controller INTRQ line
	CART Interrupt from Controller DRQ line

ROM OS:
	Appears in cartridge space $c000-dfff (Cumana system uses $c000-feff)
	Adds IRQ, FIRQ and NMI handling code, uses various Ram hooks

Hardware Interface:
	Standard Shugart compatible interface

Drives Supported:	4 (1 - 4)


2.  Dragon DOS variants
=======================

Dragon DOS 1.0:
	Original release by Dragon Data Ltd.
	Patches for EPROM appeared in Dragon User 
	(with corrections in Dragon User )
	Bugs:	No more than 127 files can be accessed
		80 Track DS disks wrongly written
		Doesn't recognise disk changes
	{7} adds the following:
		Files on DS disks could be read incorrectly if immediately
		  following thefollowing first the disk access
		First file control block was corrupted when sectors 19-36 of
		  Tr20 of a DS disk were written
		First file control block corrupted when DIR was used
		Files extensions could be appended to wrong file if >127 files
		  on the disk or the master directory entry and any extension
		  entry were separated by more than 3 sectors

Cumana Dos 1.2/2.0:
	Shipped with Cumana Disk system
	DragonDOS compatible at disk level and command level but with
	  enhanced commands (SCOPY and Tape/disk oriented copying)
	Used 8K rather than 4K eprom for OS
	Supposedly a large number of Bugs

Delta Dos from Premier Microsystems.
	Early version was Single Density ? Later versions were double density
	Record/stream oriented file handling

Eurohard Dos 3.0:


Eurohard Dos 4.0:
	Improved Dragon Dos 1.0
	Features:
		Scrolling directory, autoboot at power up
	Bugs:
		(Unknown)

SuperDos E4/5/6:
	Much improved Dragon Dos 1.0 by Mike Kerry of Grosvenor Software
	Features:
		Paged directory, fixes all known 1.0 bugs
	Bugs:
		Corrupts mem/files/hangs on FWRITE time out on open files
		RENAME allows creation of zero length filenames when used to
                copy across disks
		WP error can occur 3 or 4 times in succession.
		ERROR GOTO not always cancelled on return to BASIC
		LOAD'd files remain open
		EOF errors occurs whilst FLREADing from large fragmented files

DosPlus x.x:
	Complete rewrite by Phil Scott
	Features:
		Disk labels, close individ files
	Bugs:
		(Unknown)


3.  Disk Layout
===============

        MFM Double Density
	 40 or 80 tracks (0 - 39 or 0 - 79)
	  1 or  2 sides
	 18 sectors per track (1 - 18)
	256 bytes per sector
	2:1 interleave

Drive numbering: Dragon DOS refers to drives 1-4 (physical units 0-3),
drive 0 can also be used to refer to drive 1.

Double sided disks are usually considered as having 36 sectors per
track rather than referring to side numbers.

Logical Sector Numbers (LSNs) are used to refer to a sector relative to the
first sector on the disk.  LSN 0x000 == Track 0, Side 0, Sector 1.

40 Tracks, 1 Side,  18 Sectors:
 
  LSN 0x000  Track 0 Side 0 Sector 1
  LSN 0x012  Track 1 Side 0 Sector 1

40 Tracks, 2 Sides, 36 Sectors:

  LSN 0x000  Track 0 Side 0 Dragon Sector  1 Physical Sector 1
  LSN 0x012  Track 0 Side 1 Dragon Sector 19 Physical Sector 1
  LSN 0x024  Track 1 Side 0 Dragon Sector  1 Physical Sector 1

4.  Directory Track
===================

Track 20 contains the Directory information

Sectors 1 and 2 hold the sector bitmap

Track 20 Sector 1 identifies the disk format as follows:
Offset
0xfc	Tracks on disk
0xfd	Sectors per track (36 indicates double sided / 18 secs per track)
0xfe	One's complement of offset 0xfc
0xff	One's complement of offset 0xfd

Sectors 3 - 18 hold directory entries.
Each directory entry is 25 bytes long - 160 entries max numbered 0 - 159.
Each sector contains 10 directory entries as follows:
0x00 - 0x18	Directory Entry  1
0x19 - 0x31	Directory Entry  2
0x32 - 0x4a	Directory Entry  3
0x4b - 0x63	Directory Entry  4
0x64 - 0x7c	Directory Entry  5
0x7d - 0x95	Directory Entry  6
0x96 - 0xae	Directory Entry  7
0xaf - 0xc7	Directory Entry  8
0xc8 - 0xe0	Directory Entry  9
0xe1 - 0xf9	Directory Entry 10
0xfa - 0xff	6 unused bytes - usually 0x00 - used by some programs to
		store long disk labels

4.1  Format of Sector Bitmap
----------------------------

The sector bitmap is split across sectors 1 and 2 of track 20 
Sector 1:
0x00 - 0xb3	Bitmap for LSNs 0x000 - 0x59f
0xb4 - 0xfb	Unused - 0x00 - used by DosPlus for label and something else
0xfc - 0xff	Disk format information (see above)

Sector 2:
0x00 - 0xb3	Bitmap for LSNs 0x5a0 - 0xb3f (80 Track, DS only)
0xb4 - 0xff	Unused - 0x00

Each bit in the sector bitmap represents a single logical sector number -
0 = used, 1 = free

LSN
0x000	Sector 1 Byte 0x00 Bit 0
0x007	Sector 1 Byte 0x00 Bit 7
0x008	Sector 1 Byte 0x01 Bit 0
0x59f	Sector 1 Byte 0xb3 Bit 7
0x5a0	Sector 2 Byte 0x00 Bit 0
0xb3f	Sector 2 Byte 0xb3 Bit 7

4.2  Directory entry format
---------------------------

0x00		flag byte
	bit 7	Deleted - this entry may be reused
	bit 6	Unused
	bit 5	Continued - byte at offset 0x18 gives next entry number
	bit 4	Unused
	bit 3	End of Directory - no further entries need to be scanned
	bit 2	Unused
	bit 1	Protect Flag - file should not be overwritten
	bit 0	Continuation Entry - this entry is a Continuation Block

0x01 - 0x17	File Header Block or Continuation Block

0x18	[flag byte bit 5 == 0]
		Bytes used in last sector (0x00 == 256 bytes)
	[flag byte bit 5 == 1]
		Next directory entry num (0-159)

File Header block:  (flag byte bit 0 == 0)

0x01 - 0x08	filename (padded with 0x00)
0x09 - 0x0b 	extension (padded with 0x00)
0x0c - 0x0e	Sector Allocation Block 1
0x0f - 0x11	Sector Allocation Block 2
0x12 - 0x14	Sector Allocation Block 3
0x15 - 0x17	Sector Allocation Block 4

Continuation block:  (flag byte bit 0 == 1)

0x01 - 0x03	Sector Allocation Block 1
0x04 - 0x06	Sector Allocation Block 2
0x07 - 0x09	Sector Allocation Block 3
0x0a - 0x0c	Sector Allocation Block 4
0x0d - 0x0f	Sector Allocation Block 5
0x10 - 0x12	Sector Allocation Block 6
0x13 - 0x15	Sector Allocation Block 7
0x16 : 0x17	Unused

Sector Allocation Block format:

0x00 : 0x01	Logical Sector Number of first sector in this block
0x02		Count of contiguous sectors in this block

5.  Bootable disks
==================

The characters 'OS' at the offsets 0 and 1 of LSN 2 (Track 0, sector 3)
signify the disk is bootable.

The DragonDos BOOT command checks for this signature returning BT error
if not found.  Otherwise, Sectors 3-18 of track 0 are loaded into memory
at address $2600 and execution begins at $2602.

Note that the operation of BOOT under the original DragonDos does not set the
default drive number to that passed to the BOOT command but DosPlus does.

6.  File extensions and formats
===============================

Three standard file types exist under Dragon Dos - these are
        .DAT - standard data file
        .BAS - BASIC tokenised file 
        .BIN - binary image file

Contents of DAT file are typically in ASCII style text format

BAS and BIN are essentially the same - both start with an 9 byte header of
the following format:
     
Offset     Value

0x00       0x55
0x01       Filetype
0x02:0x03  Load Address
0x04:0x05  Length
0x06:0x07  Exec Address
0x08       $AA
0x09-      Data

Filetype is
0x01    BAS
0x02    BIN
0x03    Segmented Binary files under DosPlus {7}
Remainder are undefined under standard Dragon DOS.  

?? Result on 'RUN'ning a file of the wrong type is not known

Load Address is the data load address - typically $2401 for a .BAS file
  although unsure whether this is actually used.

Length is length of Data block that follows i.e. complete file should be
  Length+9 bytes long

Exec Address is execute address stored in $9d:9e for default EXEC addr if
  the  data/program is LOADed - if the BIN file is RUN this defines the entry
  point that is jumped to.  For a BASIC program this should be $8B8D.


7.  Added BASIC Keywords by Token value
=======================================

Keywords:

0xce	AUTO
0xcf	BACKUP
0xd0	BEEP
0xd1	BOOT
0xd2	CHAIN
0xd3	COPY
0xd4	CREATE	
0xd5	DIR
0xd6	DRIVE
0xd7	DSKINIT
0xd8	FREAD
0xd9	FWRITE
0xda	ERROR
0xdb	KILL
0xdc	LOAD
0xdd	MERGE
0xde	PROTECT
0xdf	WAIT
0xe0	RENAME
0xe1	SAVE
0xe2	SREAD
0xe3	SWRITE
0xe4	VERIFY
0xe5	FROM
0xe6	FLREAD
0xe7	SWAP

Functions:

0xa2	LOF
0xa3	FREE
0xa4	ERL
0xa5	ERR
0xa6	HIMEM
0xa7	LOC
0xa8	FRE$

8.  Description of commands added to BASIC
==========================================

AUTO (Token 0xce)
BACKUP (Token 0xcf)
BEEP (Token 0xd0)
BOOT (Token 0xd1)
CHAIN (Token 0xd2)
COPY (Token 0xd3)
CREATE (Token 0xd4)
DIR (Token 0xd5)
DRIVE (Token 0xd6)
DSKINIT (Token 0xd7)
ERL (Token 0xffa4)
ERR (Token 0xffa5)
ERROR (Token 0xda)
FLREAD (Token 0xe6)
FRE$ (Token 0xffa8)
FREAD (Token 0xd8)
FREE (Token 0xffa3)
FROM (Token 0xe5)
FWRITE (Token 0xd9)
HIMEM (Token 0xffa6)
KILL (Token 0xdb)
LOAD (Token 0xdc)
LOC (Token 0xffa7)
LOF (Token 0xffa2)
MERGE (Token 0xdd)
PROTECT (Token 0xde)
RENAME (Token 0xe0)
SAVE (Token 0xe1)
SREAD (Token 0xe2)
SWAP (Token 0xe7)
SWRITE (Token 0xe3)
VERIFY (Token 0xe4)
WAIT (Token 0xdf)


9.  Programmers Guide to DragonDOS
==================================

DragonDOS functions are available via an indirect jump table located at $c004
onwards

[$c004]	Hardware Command routine - general disk operation restore, seek, etc.
	Contents of $00ea specify operation

[$c006]	Address of data table for [$c004] ($00ea)

[$c008]	Validates filename and copies to 'current drive block'
	  On entry:
	    X points to filename e.g. '3:FILENAME.EXT'
	    B length of filename e.g. 0x0e
	    Y points to default extension to use if none is given e.g. 'DAT'.
              Use '   ' for no default extension
	  On Return:
	    Filename appears at $0650-$065a
	    CC.Z clear on error
	    B contains error code
	    U $065b always (SuperDosE6)

[$c00a]	Open a file - copies directory entry to a file control block
	  On entry:
	    Filename at $0650 ??
	  Returns:
	    CC.Z clear on error
	    A FCB number (0-9)
	    B contains error code

[$c00c]	Create a file/directory entry with backup
	  On entry:
	  Returns:
	    CC.Z clear on error
	    B contains error code

[$c00e]	%LENFIL% Reports length of file

[$c010] %CLOSAL% Closes	all open files on drive specified in $00eb
	  On entry:
	  Returns:
	    CC.Z clear on error
	    B contains error code

[$c012]	Closes a single file
	  On entry:
	    A FCB number (0-9) to close
	  Returns:
	    CC.Z clear on error
	    B contains error code

[$c014]	Read data from file to memory
	  On entry:
	  Returns:
	    CC.Z clear on error
	    B contains error code

[$c016]	Write data to file from memory, verifies if on.
	  On entry:
	    A  FCB number (0-9)
	    X  pointer to data to write
	    U  number of bytes to write
	    Y:B  24bit file pointer position to write at
	         Y  LSN of sector
	         B  byte offset within sector
	  Returns:
	    CC.Z clear on error
	    B contains error code

[$c018]	%GETFRE% Gets free space on disk

[$c01a]	%DELETE% Deletes file and frees sectors

[$c01c]	Protect/Unprotect a file

[$c01e]	%RENAME% Rename a file

[$c020]	%GETDIR% Gets a directory entry

[$c022]	Find free buffer and read sector

[$c024]	Copy updated directory sectors from Tr20 to Tr16

[$c026]	Read absolute sector

[$c028]	Write absolute sector, no verify


DosPlus adds the following functions: {7}

[$c02a]	Verify absolute sector

[$c02c]	Initialise disk

[$c02e]	Disk error codes table base address


10.  DOS Lower memory usage
===========================

$00ea		Disk operation code command byte
$00eb		Active/last used drive number (1-4)
$00ec		Track number (0-79)
$00ed		Sector number (1-36)
$00ee:00ef	Disk buffer ptr
$00f0		Disk error status byte
$00f1		Current disk file control block number (0-9)
		  0xff - no files open ??
$00f2		Number of bytes in disk buffer area
$00f3		Number of bytes to transfer to/from buffer
$00f4		Current disk type - taken from directory track on
		  first disk access after switch on or reset
			0x00  1 side  40 tracks
			0x01  2 sides 40 tracks
			0xfe  2 sides 80 tracks
			0xff  1 side  80 tracks
$00f4		{2} lists this as "Record Length Flag"
			0x00 don't care, 0xff do care
$00f5		File read/write/verify flag
			0x00 read
			0x01 write
			0xff verify
$00f6		I/O currently in progress flag
		  0x00 check for time out, Non-0x00 skip timeout check
$00f8		Sector currently seeking {SuperDos Rom}

$0600-0604	Temporary storage {2}
$0605-0609	Controller Variables {2}
$0605		Timeout count, timeout occurs when this location is
		  decremented from 0x01 to 0x00 
$0606		Hardware command byte mask for $ff40
$0607		Hardware control byte mask for $ff48 {SuperDosE6 Rom}
$0608		(0xff)
$0609		Verify flag, 0x00 Off Non-0x00 On
$060a		Default DRIVE number
$060b:060c	FWRITE buffer addr
$060d:060e	AUTO current line number
$060f:0610	AUTO line number increment
$0611		RUN/LOAD flag, 0x00 LOAD Non-0x00 RUN
$0612		FREAD/FLREAD flag {2}
$0613		AUTO flag, 0x00 Off Non-0x00 On
$0614		ERROR GOTO flag, 0x00 Off Non-0x00 On
$0615:0616	ERROR GOTO trap line number
$0617:0618	ERL Line number containing last error
$0619		ERR Last error number
$061a:061b	Address of statement in error
$061c-0621	Drive 1 details - 6 bytes
		  Offset:
		    0x00
		    0x01
		    0x02
		    0x03
		    0x04
		    0x05 (0x00)
$0622-0627	Drive 2 details
$0628-062d	Drive 3 details 
$062e-0633	Drive 4 details 
$0634-063a	Disk Buffer 1 details - 7 bytes
		  Offset:
		    0x00:0x01	LSN ?
		    0x02	(0x00) ?? tested for 0x55, 0xff
		    0x03	Drive # ? (1-4)
		    0x04	Buffer priority # ?? (0x04)
		    0x05:0x06	Buffer address ($0800)
$063b-0641	Disk Buffer 2 details 
$063f		Disk Buffer 2 ?? (0x03)
$0640:0641	Disk Buffer 2 address ($0900)
$0642-0648	Disk Buffer 3 details
$0646		Disk Buffer 3 ?? (0x02)
$0647:0648	Disk Buffer 3 address ($0a00)
$0649-064f	Disk Buffer 4 details 
$064d		Disk Buffer 4 ?? (0x01)
$064e:064f	Disk Buffer 4 address ($0b00)
$0650-0682	Current drive information 
$0652:0653	Start addr of program loaded
$0654:0655	Length of program loaded
$0656:0657	Exec addr of program loaded
$0678:0679
$067d		FCB number
$0683-0696	USR vector table relocated from $0134-0147
$0697-069a	Drive on line flag - one per drive
		  0x00 off line Non-0x00 on line
$0697:0698	CumanaDOS - AUTO current line number {1}
$0699:069a	CumanaDOS - AUTO line number increment {1}
$069b-069e	Current track - one per drive
$069b		CumanaDOS - AUTO flag, 0x00 Off Non-0x00 On {1}
$069c:069d	CumanaDOS - ERROR GOTO line number {1}
$069e		CumanaDOS - ERROR GOTO flag, 0x00 Off Non-0x00 On {1}
$069f-06a2	Head stepping rate - one per drive (0x02) {4} & {5}
		  0x00	 6ms <- this can safely be used with most drives
		  0x01	12ms
		  0x02	20ms <- this is default
		  0x03	30ms
$069f:06a0	CumanaDOS - ERL Last error line {1}
$06a1		CumanaDOS - ERR Last error code {1}
$06a3-06a6	Tracks on disk - one per drive
$06a7-06aa	Sectors per track - one per drive
$06ab-06bc	Directory Sector status
$06bd-06db	File Control Block 0 - 31 bytes each
		Offset: 0x00 - 0x07	Filename
			0x08 - 0x0a	Extension
			0x0b		Drive number (1-4)
			0x0c
			0x0d
			0x0e
			0x0f
			0x10
			0x11 - Flag ?
			0x12
			0x13
			0x14
			0x15
			0x16
			0x17
			0x18
			0x19
			0x1a
			0x1b
			0x1c
			0x1d
			0x1e
$06dc-06fa	File Control Block 1
$06fb-0719	File Control Block 2
$071a-0738	File Control Block 3
$0739-0757	File Control Block 4
$0758-0776	File Control Block 5
$0777-0795	File Control Block 6
$0796-07b4	File Control Block 7
$07b5-07c3	File Control Block 8
$07c4-07f2	File Control Block 9
$07f3-07ff	Temporary Variables
$0800-08ff	Disk Buffer 1
$0900-09ff	Disk Buffer 2
$0a00-0aff	Disk Buffer 3
$0b00-0bff	Disk Buffer 4

11.  DOS Rom reference
======================

See memmap.txt for the usage of low memory $0000-$0bff.
See romref.txt for any BASIC ROM calls $8000-$bfff and abbreviations used.

Dragon DOS (All presumed v1.0 unless stated otherwise)

$c000:c001	'DK' - used by BASIC Rom init to detect Disk Rom
$c002-c003	Cartridge Init entry point (BRA $c0xx)
$c004-c029	Indirect address table
$c004:c005	Low Level Hardware Command byte routine ($cxxx)
$c006:c007	($00ea)
$c008:c009	($cxxx)
$c00a:c00b	($cxxx)
$c00c:c00d	($cxxx)
$c00e:c00f	%LENFIL% Reports length of file ($cxxx)
$c010:c011	%CLOSAL% Closes	all open files ($cxxx)
$c012:c013	($cxxx)
$c014:c015	($cxxx)
$c016:c017	($cxxx)
$c018:c019	%GETFRE% Gets free space ($dxxx)
$c01a:c01b	%DELETE% Deletes file ($cxxx)
$c01c:c01d	Protect/Unprotect a file ($dxxx)
$c01e:c01f	%RENAME% Rename a file ($dxxx)
$c020:c021	%GETDIR% Gets a directory entry ($dxxx)
$c022:c023	($dxxx)
$c024:c025	($cxxx)
$c026:c027	($dxxx)
$c028:c029	($dxxx)
$c0fc		Writes a sector to disk
$c104		Read sector from disk
$c165		Drive/Hardware Init
$c169		Low level Hardware I/O routine to send cmd
$c397		DSKINIT token dispatch address
$c3bc		Formats disk in DEFD drive {1}
$c520		BACKUP token dispatch address
$c64c		Reserved words token dispatch routine
$c667		Function token dispatch routine
$c69e		Ram Hook JMP from System error trap at $0191
$d14d		Get free space on current drive
$d311		Convert Logical Sector Num in Y to physical track/sector
$d332		COPY token dispatch address
$d3e5		MERGE token dispatch address
$d490		Ram Hook JMP from RUN Link at $0194
$d4a7		LOAD token dispatch address
$d503		CHAIN token dispatch address
$d53f		SAVE token dispatch address
$d720		Ram Hook JMP from LINE INPUT from DEVN at $0182
$d725		CREATE token dispatch address
$d774		KILL token dispatch address
$d781		PROTECT token dispatch address
$d7a5		RENAME token dispatch address
$d7c7		FLREAD token dispatch address
$d7fb		FREAD token dispatch address
$d8a5		FWRITE token dispatch address
$d8fa		Ram Hook JMP from O/p chr in A to DEVN at $0167
$d902		Ram Hook JMP from Device Open at $015e
$d917		Ram Hook JMP from Close file at $0176
$d960		Ram Hook JMP from Re-request keyb i/p at $017c
$da35		DIR token dispatch address
$da3c		%DIRDSK% Directory of current disk to DEVNUM (CoCo $cbcf) {1}
$dadc		AUTO token dispatch address
$db90		BEEP token dispatch address
$dba5		Beep B times
$dbc1		WAIT token dispatch address
$dbcb		Wait for time X milliseconds
$dbd5		SWAP token dispatch address
$dc03		BOOT token dispatch address
$dc0a		Boots disk in current drive
$dc3c		DRIVE token dispatch address
$dc49		ERROR token dispatch address
$dc79		SREAD token dispatch address
$dcc8		SWRITE token dispatch address
$dd36		VERIFY token dispatch address
$dd4d		Ram Hook JMP from Check EOF on DEVN at $0188
$dd7a		LOC function token dispatch address
$dd88		LOF function token dispatch address
$dda3		FREE function token dispatch address
$ddbb		ERL function token dispatch address
$ddc1		ERR function token dispatch address
$ddc7		HIMEM function token dispatch address
$ddcb		FRE$ function token dispatch address
$debb		Function words table
$ded4		Reserved words table
$e56d		Cumana DOS - Sector Read routine {1}
$e643		Cumana DOS - Sector Write routine {1}

SuperDos E6

$c000:c001	'DK' - used by BASIC Rom init to detect Disk Rom
$c002-c003	Cartridge Init entry point (BRA $c02a)
$c004-c029	Indirect address table
$c004:c005	Hardware Command routine ($c168)
$c006:c007	($00ea)
$c008:c009	Validates filename ($c7e8)
$c00a:c00b	Open a file ($c8a8)
$c00c:c00d	Create a file ($cf3a)
$c00e:c00f	%LENFIL% Reports length of file ($ce9f)
$c010:c011	%CLOSAL% Closes	all open files on drive in $00eb ($cee1)
$c012:c013	Closes single file ($cef7)
$c014:c015	read data from file ($c9bd)
$c016:c017	write data to file ($cb7f)
$c018:c019	%GETFRE% Gets free space ($d173)
$c01a:c01b	%DELETE% Deletes file ($cfdf)
$c01c:c01d	Protect/Unprotect a file ($d0c5)
$c01e:c01f	%RENAME% Rename a file ($d0f7)
$c020:c021	%GETDIR% Gets a directory entry ($d204)
$c022:c023	($d276)
$c024:c025	($c75e)
$c026:c027	($d337)
$c028:c029	($d327)
$c02a-c09c	Cartridge init code
$c09d-c0da	Inits DOS workspace area and buffers
$c0dd-c0ed	Disk motor spin up delay subroutine - if motor is not active
		  ($0605 == 0x00) then a X is decremented from 0xd800 before
		  returning.  Value in A on entry is stored in $0605
$c0fb		Subroutine
$c101		Subroutine
$c104		Subroutine
$c15e		Subroutine
$c161		Subroutine
$c164		Hardware init
$c168		Low level Hardware I/O routine to send cmd
$c28a-c2c0	Subroutine - clears any current disk operation, checks drive
		  number in $00eb, enables motor and NMI interrupt, sets
		  current track in $ff41 then calls $c0dd with A=0xd2
$c29c		Some unused Ram hooks JMP here (RTS)
$c39e-c3b3	Subroutine to enable/disable write-precompensation on disk
		  controller via bit 4 of $ff48 for a track number (from
		  $ff41) > 16 
$c3b4		DSKINIT token dispatch address
$c508-c539	Subroutine to place a tracks worth of formatting data in
		  buffer pointed to by $00ee:00ef
$c544		BACKUP token dispatch address
$c670		Reserved words token dispatch routine
$c68b		Function token dispatch routine
$c6a1-c6b2	Subroutine
$c6b3		Sub to read drive num by evaluating next
		  expression, used by DRIVE, BOOT, returns in B
$c6c5		Ram Hook JMP from System error trap at $0191
$c706-c71d	RESET Interrupt service routine 
$c71e-c726	NMI Interrupt service routine
		  Assumes DP=0xff on NMI occurring - possible bug?
		  CLRs B and DP, removes 12 bytes from stack, A contains
		  status at $ff40 on return
$c727-c74d	IRQ Interrupt service routine
		  CLRs DP, decrements $0605 if $00f6 == 0x00, if $0605 is
		  decremented from 0x01 to 0x00, $c75e is called and motor is
		  stopped

$c75e		Called from IRQ driven motor timeout
$c7da-c7e0	FIRQ Interrupt service routine
$c8a8		Subroutine
$cc12		Subroutine
$ced2-cee0	Returns FCB data address in X from FCB num(0-9) in $00f1
$cee1-cef6	Closes all files on current drive in $00e6 by calling
		  $cef9 with FCB numbers in $00f1
$cef7-		Closes FCB (0-9) specified in A
$cef9-		Closes FCB (0-9) specified in $00f1
$cf3a		Subroutine
$d0e4		Subroutine - on entry A = FCB number (0-9) stored in $00f1
$d0f7		Subroutine
$d123		Subroutine
$d1a3-		Subroutine called by close FCB at $cef9
		  If drive online returns B=0, X=ptr 6 bytes of drive details
		    U ptr drive online flag, A=drive num (0-3)
$d237		Subroutine
$d24a		Subroutine
$d276		Subroutine
$d2a2		Subroutine - searches for a drive buffer detail block with a
		  priority of 0x01
$d2cb		Subroutine
$d2e2-d326	Subroutine
$d327		Subroutine
$d33e		Subroutine
$d35f		COPY token dispatch address
$d410		MERGE token dispatch address
$d4b7		Ram Hook JMP from RUN Link at $0194
$d4ce		LOAD token dispatch address
$d562		SAVE token dispatch address
$d5f9		CHAIN token dispatch address
$d6c5		Subroutine
$d6d1		Subroutine
$d6f5-d70f	Ram Hook JMP from Close file at $0176
		  Also called from Dskinit routine
		  Closes all open FCBs and clears drive online flags ($0697)
$d710-d714	Clears drive online flags & JMPs $ba77
$d71f		CREATE token dispatch address
$d767		Subroutine
$d76d		KILL token dispatch address
$d77a		PROTECT token dispatch address
$d79d		RENAME token dispatch address
$d7be		FLREAD token dispatch address
$d7f0		FREAD token dispatch address
$d879		Subroutine
$d897		FWRITE token dispatch address
$d8ec		Ram Hook JMP from Verify Device Number at $0161
$d8f4		Ram Hook JMP from Device Open at $015e
$d90b		Ram Hook JMP from O/p chr in A to DEVN at $0167
$d954		Ram Hook JMP from Re-request keyb i/p at $017c
$da28		DIR token dispatch address
$dac5		Ram Hook JMP from LINE INPUT from DEVN at $0182
$dae5		AUTO token dispatch address
$dba0		BEEP token dispatch address
$dbc3		WAIT token dispatch address
$dbd7		SWAP token dispatch address
$dc08		Subroutine
$dc0d-dc45	BOOT token dispatch address
$dc46		DRIVE token dispatch address
$dc52		ERROR token dispatch address
$dc82		SREAD token dispatch address
$dcd1		SWRITE token dispatch address
$dd3d		VERIFY token dispatch address
$dd54		Ram Hook JMP from Check EOF on DEVN at $0188
$dd81		LOC function token dispatch address
$dd8f		LOF function token dispatch address
$dda9		FREE function token dispatch address
$ddc1-ddc6	ERL function token dispatch address
		  Returns value in $0617:0618 with JMP $8c37
$ddc7-ddcc	ERR function token dispatch address
		  Returns value in $0619 as 16bit with JMP $8c37
$ddcd-ddd0	HIMEM function token dispatch address
		  Returns value in $0027:0028 with JMP $8c37
$ddd1-ddd9	FRE$ function token dispatch address
		  Performs a String space 'Garbage collection' with a call to
		  $8cd7.  Returns $0023:0024 - $0021:0022 with JMP $8c37
$ddda-dde9	Indirect jump table of 8 routines
$ddea-ddfb	18 byte table of sector numbers to create 2:1 interleave when
		  formatting disk track
$ddfc		Terminator byte (0x00) for above table
$ddfd-de23	Data sent to Disk controller during track format
$de24-de58	Init data in fmt: byte count, dest address, data
$de24-de2f	0x09, $0109, data for Interrupt vectors
$de30-de36	0x04, $069f, data for Step rate settings
$de37-de55	0x1e, $012a, data for Stub 1 and 2
$de56-de58	0x00, 0x0000 terminator
$de59-de8c	Reserved words token dispatch table
$de8d-de9a	Function words token dispatch table
$de9b-dec0	Ram hook vectors copied to $015e-0196
$dec1-ded9	Function words table
$deda-df5a	Reserved words table
$df5b-df6d	'INSERT SOURCE    ', 0x0d, 0x00
$df6e-df86	'INSERT DESTINATION     ', 0x0d, 0x00
$df87-df9d	'PRESS ANY KEY        ', 0x0d, 0x00
$df9e-dfa9	Extension Table 'BASDATBIN   '
$dfaa-dfcf	Error code table
$dfd0-dfd1	'??'
$dfd2-dfdf	Sign on message 'SUPERDOS E6 ', 0x0d, 0x00

CoCo DOS
$cbcf		Directory same as DIR (Dragon $da3c) {1}
$d7ae		NMI Interrupt service routine {1}
$d7bc		IRQ Interrupt service routine {1}

References
==========

{1}	'The Dragon Notebook', Ray Smith, NDUG.
{2}	'Inside the Dragon', Duncan Smeed and Ian Sommerville,
	   Addison-Wesley, 1983.
{3}	'TRS-80 Color Computer Tech Ref Manual', Tandy Corp, 1981.
{4}	WD2797 Floppy Disc Driver Controller Data Sheet (RS Components #6991).
{5}	Dragon Disc Controller Circuit Diagram, ex Dragon Data Ltd, now NDUG.
{6}	Dragon 32/64 Upgrade Manual, R. Hall, NDUG, 1985.
{7}	'Boss Dos', R.E. Warwick, p6, Dragon User, Feb 1987.