!I. INTRODUCTION
     The disk operating system described in this manual is modeled after the
ATARI (trademark of ATARI Corp.) disk operating system (DOS 2),  and may be
considered an extension of the very "user friendly" concepts  introduced with
this operating system. The ATARI 810 disk drive and the ATARI 1050 disk drive
are well supported by the DOS 2 and DOS 2.5, but those DOSs have very limited
provision for higher capacity double density disks (such as the XF-551), and
large RAMdisks.


!II. SYSTEM REQUIREMENTS

     MYDOS 4.51 is intended to function as nearly as possible like ATARI DOS
2.  This means it occupies as little memory as possible, supports all the
system calls supported by DOS 2, and in most cases uses exactly the same
parameters to the system calls.  This means compatibility, yet MYDOS goes  far
beyond this.  On a standard single sided, single density disk, MYDOS will read
and write to a DOS 2.0 or 2.5 format, and vice versa.  But there are a few
programs that will not run under MYDOS because of one or both of the following
reasons:

         direct "illegal" calls into the main DOS or FMS code, and

         relying upon exact directory data formatting (i.e., 3 digit sector
counts).

     MYDOS will run on any 8-bit Atari computer with at least one disk drive
(that is compatible with DOS 2).  MYDOS 4.51 has full READ compatibility with
the DOS 2.5 format, but will only write to the first 720 sectors of the disk.
(MYDOS has its own format for enhanced density disks that allow full access.)
It is not compatible at this time with the OS/A+ version 4 format, or the
SpartaDOS format.

     Up to eight disk drives (or nine if the ninth is a RAMdisk) may be
accessed, but only one is required.  The resident part of the operating system
(DOS.SYS) supports all documented functions of the DOS 2 operating system, so
MYDOS supports most available software for the ATARI home computers.

     The memory available to a program is affected only by the number of files
to be open concurrently:  each disk file that may be open at the same time
requires 256 bytes of buffer space. Unlike Atari DOS 2, memory  requirements
are independent of the number of disk drives or the sector size and density.
The need for a 256 byte buffer for each concurrently open file means that
programs that keep large numbers of files open will have less memory available
than under DOS 2 and as a result some programs (mostly older versions of
compilers and language interpreters) will not have enough memory to run.  With
three file buffers (which is the default) and no resident drivers (such as for
RS232 support), MYDOS 4.51 permits binary programs to load as low as $1F80.

     MYDOS 4.51 also contains a very versatile RAMdisk driver than can handle
upgrades up to 1 megabyte that follow the guidelines of the expanded  memory on
the 130XE, or the Axlon upgrade for the 800.  MYDOS also has a feature that
will determine how much memory you have, and set itself up for your machine
automatically if the memory hardware is 130XE compatible.


!III. MENU FUNCTIONS

     The menu provided by MYDOS 4.51 identifies 18 common tasks that might need
to be done. Rather than having to write a utility program (only a few lines of
BASIC would perform most of the menu functions) or even remember the name and
format of a DOS command, these tasks can be handled by entering a single
letter. MYDOS responds with a question asking for the details of the operation
(which file, what density,  I"are you sure?" I or whatever else it might need to
know).

     After you enter the remaining information, the function is performed and
another prompt is displayed.

     You should notice two interesting things about the menu: the second line
on the screen identifies the disk drives present on the system and what they
appear to MYDOS to be (single or double density, RAMdisk or high capacity hard
disk).  The next line describes the current default directory (that directory
used when a disk is referenced by "D:" (without a unit  number after the "D" -
this feature will be described later). The second thing to notice is that after
commands fill the screen, the menu "rolls" off the top: some DOS programs (e.g.
Atari DOS 2) keep the menu, MYDOS does not. This permits more information to be
displayed when a long sequence of commands are done, or when many files are
copied. To restore the menu to the screen, just type RETURN, and the initial
screen will be restored.

    If you wish to abort a command at any point, simply press BREAK.  This will
return you to the prompt.  Pressing BREAK or RESET while writing to a disk will
not cause any damage; however, the file you were writing will probably not be
displayed in the directory, and the free sector count may be incorrect.

     When entering a filename, the drive number should be entered, followed by
a ":", and then the rest of the filename. If the drive number and ":" are not
entered, the default drive (and directory) will be used.  In the [C]opy file
option, entering the drive number only will result in copying every file on the
main directory of that drive.  A drive may be specified like this: "1", "1:",
or "D1:".  If you wish to specify the file or set of files to be referenced,
the drive format must include a ":" or it must be omitted entirely (for the
default drive and directory).  Examples: D1:Test.obj, 1:TEST.ASM, or D2TEST
(really D1:D2TEST) are valid file names, but d1:Test.obj (the D in the drive
specification must be upper case) and 1TEST.ASM (though it is interpreted as
D1:TEST.ASM currently) are not proper file names.

     The file name itself is either fully specified (referring to the entire
name as it is on the disk) or includes "wild card" characters (specifying a set
of files). A fully specified file name consists of one to eight characters
followed by a period (".") and zero to three additional "extention"
characters.  The characters in the file name may be upper or lower case
letters, numbers, the underscore character ("_") or the character "@".  The
only exception is the first character - it may not be a number.  The "wild
card" characters are the characters "*" and "?":  the character  "*" or the
sequence ".*" end the 8 character file name and the character "*" neds the 3
character file extension field in the file name and match all possible
characters.  The character "?" matches only one single file name character.
Examples: "*.BAS" will match every file ending with .BAS.  "TEST?.*" will match
files TEST.BAS, TEST1.OBJ, but will not match TESTER.BAS.

     In addition to the main directory (containing up to 64 files or
subdirectories), each MYDOS disk may also contain additional subdirectories of
64 files each.  You may use one of two possible characters to separate the
subdirectory name(s):  the ":" colon, or the ">" greater-than sign.  If the
main directory contained the subdirectory BAS and a file named GRAPHIC1 were in
the subdirectory file BAS, it could be referenced with the filename
BAS:GRAPHIC1 (or BAS>GRAPHIC1).  If instead, GRAPHIC1 were in the subdirectory
GR.dir which in turn were in BAS, then the reference would be to
BAS:GR.dir:GRAPHIC1 (and so on with as many names as needed).  MYDOS does not
demand consistency, so it could also be referred to as BAS:GR.dir>GRAPHIC1,
also.  Because there is no limit to the number of subdirectories on a disk
(other than the buffer size of programs using the directories and number of
available sectors on the disk), a single diskette can contain hundreds of small
files if necessary.  Each subdirectory is actually an 8 sector file to its
parent directory.  Thus it can contain 64 files or subdirectories like the 8
sector root directory.

     If a disk directory includes the files TEST.ASM, TEST.OBJ, TEST.C,
TEST.ALM, TEASET.DOC, TRACE.FIL, and BETS.LST, the specification "t*.*" will
not match any file name (since "t" and "T" are not the same letter to MYDOS,
though they are to DOS 2).  The specification "T**" will match all but
"BETS.LST" (since the others all begin with the letter "T").  The specification
"?E??.*" will match the first four files and the last one (since the 8
character part of the file name must have no more than 4 characters in it and
the second character must be an "E").  The specification "*.?" will match only
the file TEST.C (since it is the only file name with a single character in the
3 character field).  The specification "????E**" will match the files
TEASET.DOC and TRACE.FIL and none of the others (since the 8 character part of
the file name must have at least 5 characters and the fifth must be an "E").
Note that MYDOS does not always require the "." (period) to separate the
extender from the 8 character filename.  Examples:

     FILENAME.EXT  could be entered as FILENAMEEXT; TES*.* could be TES**,
     but TEST.* could NOT be entered as TEST* (Why?).


!IV. THE MENU COMMANDS
!!  A. List a Directory or a Set of Files

     The "A" command will list the files on a disk with their sizes, followed
by a line specifying the number of free sectors on the disk.  If the line
starts with a "*", the file has been locked and may not be modified or deleted
without first being unlocked.  A ":" before the file name marks those files
that are subdirectories.  These files cannot be read or written (like normal
files) but they can only accessed as directories or deleted (when they are
empty).  File lengths and the number of free sectors are reported as 4 digit
decimal numbers (most other Atari DOSs report the values as 3 digit numbers).

     If the number of free sectors on a drive exceeds 9999, the free sector
line will contain a 5 digit number, and be one character longer.  If a file is
longer than 9999 sectors, the blank between the file extender and its sector
count will contain the most significant digit (in this case, the line size does
BNOT Bchange).

     No indication is made of the format of the file but ATARI DOS 2.0, 2.5,
and MYDOS are the only three supported file formats.  SpartaDOS or OS/A+
Version 4 files must be converted to single or double density Atari DOS 2 files
first in order to be usable from MYDOS.  See Section VI for more detailed
directory information should you need it.

     The "A" command will list the directory information to the screen if only
one file specification is entered. If two are entered, the second is taken as a
destination file and will be overwritten (or appended to if the /A flag is
used) with the directory data. Use "2,D1:DIR.TXT"  to  save the directory data
of drive 2 to a text file DIR.TXT  on drive 1. The entry "1,P:" will give you a
printout of the directory of drive 1.

     To list the files in a subdirectory, enter the name of the directory
followed by a ":" colon or ">" greater-than sign.  For example, "1:TEST:BAS:"
will list the files in the subdirectory BAS which in turn is in the
subdirectory TEST in the main directory of the diskette in drive 1. Using
"D1:TEST>BAS>" will achieve the same results.


!!B. Run the Cartridge
     The "B" command returns control to the cartridge in the left (or only)
cartridge  slot.  If no cartridge is present, an error is displayed, and
nothing happens.  No additional information is required, so if a cartridge is
present, it is entered after loading MEM.SAV (if enabled) or immediately.


!!C. Copy a File or a Set of Files

     The "C" command is used to make another copy of one or more files of
data.  The two file specifications asked for after entering the "C" identify
the source and the destination of the information being copied.  Either may be
fully specified disk file or a device specification (such as E:, P: or one of
the RS232 ports R1: to R4:).  The destination may be a set of disk files
(specified with "*" and "?"s) only if the source specifies a file name for the
destination to use.  The source may be a set and the destination a single disk
file, but unless the "/A" modifier is specified to append each copied file to
the end of the previously copied files, only the last source file will remain
on the destination disk.

     Note  that the "C" command always uses the full memory space for a copy
operation (unlike ATARI DOS 2) and as a result, it will always invalidate
MEM.SAV.  Any pending program cannot be restarted after a "C" or "J" command.

     There are several options when entering files to copy.  As with all
filename inputs, the default drive and directory (whatever "D:" is equal to on
the top status line) will be used if Dn: is not specified.  Using "/Q" at the
end of the line will query you for each source file it finds (useful for
copying certain files but specifying *.*)  if  you  wish to copy it.  Using
"/S" will copy all files EXCEPT those  with the first letter of the extender
being "S" (that is, it will omit all *.S?? files).  This emulates DOS 2.0's [O]
copy file option, and is useful when you want to copy all files except .SYS
files. The last option is the "/X" parameter.  This will prompt you for disk
swaps, even if the source and destination drives are not the same number. Here
are some examples of using the [C]opy file(s) command:

     "TEST.BAS"  will  copy  the  file  TEST.BAS on the default drive (and
directory) to the same drive, but prompt you to insert the destination disk.
(Just like the [O] command in DOS 2.0.) "D1:TE*.*,3" will copy all files on
drive 1 starting with the letters "TE" to drive 3.  "D4:DIR>*.TXT,E:/Q" will
copy all files in the directory DIR on drive 4  with the extension ".TXT" to
the screen, but will ask for confirmation before reading each one.
"2:ADD,2:LIST/A" will append the data in the file ADD on drive 2 to the file
LIST on drive 2.


!!D. Delete a File or Set of Files
     The "D" command will remove all files that match the file specification
entered, asking for confirmation before each one is removed.  The "Delete file
xxx?" prompts may be disabled by adding "/N" to the filename.  In this case,
all the matching files will be removed  "quietly", and the only further
indication you will see is the prompt for the next command.


!!E. Rename a File or Set of Files

     The "E" command changes the name of the source file or files to match the
specification in the destination.  Unlike other file specifications, the
destination specification BMUST Bconsist  of a single file name (perhaps
containing wild card characters): it must not contain any directory names or a
disk drive number.  For example, "D2:TEST>BASIC>NOTPNT.BAS,RANDIO.BAS" is the
line entered to change the name of a file in the directories "D2:TEST>BASIC>".
To change the name of the directory "BASIC" to "ATBASIC", the line would look
like "D2:TEST>BASIC,ATBASIC". One word of caution:  Never rename more than one
file to another name without wildcards  in the destination.  For example,
renaming "*.*" to "TEST" would rename BEVERY Bfile to "TEST", making it
impossible to retrieve files other than the first one!


!!F. Lock a File or Set of Files
     The "F" command limits access to the files identified.  "Locked" files may
not be deleted, renamed, added to, or replaced without being first unlocked
with the "G" command.  When a directory is listed, the files that have been
locked will be marked with an "*" in the first column. The files that are
locked may be read or loaded and executed normally, only modification or
removal are prohibited.  A locked directory cannot be deleted or renamed and no
files may be written to it.  The files already in it are not locked however.

     MYDOS  will ask you for confirmation on each file,  "Lock xxx?", unless
you override this feature by adding "/N" to the filename.


!!G. Unlock a File or Set of Files

     The "G" command removes the limitations imposed on a file when it is
"locked" using the "F" command.  It does not alter the file or otherwise change
the way the file is accessed or used.  The same function may be performed in a
program using the CIO function to "unlock" a file.

     As with the "F" function, MYDOS will ask you for confirmation ofeach
file to be unlocked,  unless you specify the "/N" parameter
     after the filename.


     H. Write MYDOS to a Disk

          The  "H"  command is used to make a bootable copy of the current
     MYDOS  4.51  files  in memory. The two files created or rewritten are
     "DOS.SYS"  and  "DUP.SYS". "DOS.SYS" is the permanently resident file
     management  routine  accessed  through  CIO  and  the small interface
     package  that loads and saves MEM.SAV (an image of the part of memory
     used  to  hold the nonresident part (DUP.SYS) of MYDOS), and the code
     to load the menu portion of MYDOS  ("DUP.SYS"). The file "DUP.SYS" is
     a  standard  binary  load  file  containing the part of MYDOS that is
     overwritten  when  a  program is loaded into memory. Neither of these
     files  may  be  interchanged  with  any other version or type of disk
     operating  system;  both  should be treated as a single object. Never
     copy  only  DOS.SYS  or  only  DUP.SYS  to a disk without copying the
     other,  unless  you  will  never  access  the DUP.SYS menu (called by
     typing  "DOS"). The files written to the disk by the "H" command will
     reflect  the  configuration parameters currently in memory, which may
     be  different  from  the ones active if the system were rebooted from
     the  master  disk  again. (See Section IV.O., configuring the system,
     for  the  definition  of the configuration parameters provided in the
     system and how to specify a modified configuration.)


     I. Initialize a Diskette

          The  "I"  command is used to "Format", or prepare a new disk for
     use with the MYDOS operating system, or to remove all the files on an
     old  disk.  The result of the "I" command is a completely empty disk.
     The  only  data  on  the diskette is that system provided information
     defining  the  space  available  and the empty main directory. If the
     drive  number  is followed by a "/N" parameter, the diskette will not
     be  reformatted,  but  just  "erased"  (the directory sectors will be
     rewritten).  If  a  disk  has  recently  been  formatted, this is the
     fastest way to remove all the files on a diskette, rather than to use
     the  "D" command. Use this option ONLY if you know the disk was good,
     for  this  does not verify the integrity of the disk. Due to a bug in
     some  hard  disk  interfaces,  this  "/N"  parameter may be needed to
     initially format the hard disk partitions.

          A  diskette  may  also  be  formatted in the Atari 1050 enhanced
     format  by  responding  to  the  question  "(Type  [A]  to  format in
     Enhanced)  Type  [Y]  to  format  drive x:" with a "A" (presuming the
     drive  is a 1050 drive or compatible with the 1050). The diskette is,
     however,  not  compatible with the diskettes similarly created by DOS
     2.5.  The MYDOS diskette will not be readable by DOS 2.5, but DOS 2.5
     enhanced disks can be fully read by MYDOS.

          An  additional note: it is a good idea to set the density of the
     drive  you  are  about  to format, unless the drive is not capable of
     double  density.  (see  the  "P"  command  for information on setting
     density.)  Otherwise,  MYDOS  will format the drive in the density of
     which it was last accessed.


     J. Duplicate a Diskette

          The  "J" command copies all the information from one diskette to
     another.  The  information  to  be copied form the source diskette is
     determined  by  specifying a starting and an ending sector number. If
     the  range is not stated, the sectors marked as in use in the DOS bit
     map  (on the VTOC sectors) are copied. The VTOC may be constructed by
     Atari  DOS  2, any version of MYDOS or any other compatible operating
     system.

          Specifying  a  sector  range  is  done  by  adding  two  numbers
     separated  by  a  dash  and enclosed in parentheses to the end of the
     drive  specification(s).  For  example, to copy sectors 19 through 54
     (tracks  1  through 3) from drive 1 to drive 3 without formatting the
     diskette  in  drive  3,  the command line could be "1,3/N(19-54)". To
     copy  the  entire  disk  from drive 1 to drive 2 after formatting the
     diskette  in  drive  2 the command could be "1,2(1-720)". This is the
     proper  way  to duplicate a non-MYDOS compatible diskette (of course,
     copies  of  "copy  protected" disks will not normally be usable after
     copying  but  data  disks  for  some word processors and games can be
     backed  up this way). Enhanced density disks may be duplicated in the
     same manner: "1,2(1-1040)".

          If   the  destination  disk  is  already  a  properly  formatted
     diskette,  the "/N" modifier may be entered after either drive number
     to  skip  the  formatting  of  the  destination drive. Otherwise, the
     destination  diskette  will  be  formatted  before  the data from the
     source  is copied to it. That is, either "1/N,2" or "1,2/N" will copy
     from  drive  1  to  drive  2 without first formatting the diskette in
     drive 2.

          Note  that  the  "J" command, like that in ATARI DOS 2, will use
     all of available memory to duplicate the diskette: this means that if
     memory  has  been  saved using the MEM.SAV file, it will no longer be
     valid.  Any  pending  program  cannot be restarted after a "C" or "J"
     command.


     K. Save Memory to Disk

          The  "K"  command  builds a binary load file containing the data
     from  the  memory area specified, as well as adding an initialization
     and  a run vector address if specified. If the file is not to execute
     an  initialization routine on being loaded, the initialization vector
     should  be  omitted.  If  it  is  not to run on being loaded, the run
     vector  should also be omitted (trailing commas need not be entered).
     If  either  vector is entered as zero, that is equivalent to omitting
     it.  Note  that  the starting and ending addresses of the program and
     both  entry  points  are all specified as hex numbers. You may append
     data  to  another file by using the "/A" parameter.  This command may
     also be used for just adding a Run address to a binary file. Example:
     "D1:PROGRAM.OBJ/A,0,0,,4000"  would  add  the run address of $4000 to
     the program "PROGRAM.OBJ" on drive 1.

          If  MEM.SAV  is  active  when  the  "K"  command is entered, the
     MEM.SAV file is loaded before writing the file to the disk.


     L. Load Memory from a File/Disable MEM.SAV

          The "L" command takes a binary load file from the disk and loads
     it  into  memory.  The  load file's initialization routine(s) will be
     executed  and  the program started at its run address unless the "/N"
     parameter  is  added  to  the  file name. If the file is not a binary
     file, you will be returned with an "Error -- 180". A binary file that
     is corrupted will usually return an "Error -- 181".

          This  command  also  disables the MEM.SAV feature before loading
     and  executing  the program. To just disable MEM.SAV, press "L", then
     [RETURN] (instead of entering a file name).


     M. Run at Address

          The  "M" command is used to enter a program loaded without a run
     address,  or  to  jump into any program without the need for a return
     address.  It  may  be  used  to  restart  the  computer  (loading the
     AUTORUN.SYS  file, if any, or a new DOS, etc...) by specifying "E477"
     as  the  jump  address.  If  MEM.SAV  is active (enabled with the "N"
     command  and  not since disabled by the "L" command), the contents of
     memory  will  be  restored from MEM.SAV before jumping to the address
     specified.


     N. Load MEM.SAV from a File/Enable MEM.SAV

          The "N" command takes a binary load file from the disk and loads
     it  into memory, just as does the "L" command. The difference is this
     command  enables  the MEM.SAV file before loading (and executing) the
     program;  and  when  control  is  returned  to MYDOS, the contents of
     memory will be saved back to MEM.SAV.

          To  just  enable  MEM.SAV,  first enter this DOS menu (by typing
     "DOS" in BASIC), then press "N" and [RETURN]. From BASIC you may also
     "POKE 1982,160" to enable MEM.SAV without going to DOS.


     O. System and Drive Configuration

          The "O" command is used to specify the type (at least logically)
     of  the  disk  drives  on  your  computer and is also used to specify
     several  system  configuration  parameters such as the number of file
     buffers  provided  or  whether  a  RAMdisk  is  present.  The  system
     configuration functions, which are not specific to individual drives,
     are  selected  by  pressing  [RETURN]  at the prompt "Drive number or
     RETURN:".  The  following  table  explains all the prompts for system
     configuration:

     Verify WRITEs?          N=do not write with verify, else do verify

     Number of File Buffers? The number of disk files that can be open
                             at once (RETURN = 3)

     RAM disk present?       N=no RAM disk on the system (skips the
                             next 4 questions as well), else the
                             RAMdisk is enabled, and the next questions
                             determine what kind it is.

     [A]xlon or [X]E type?   A=Axlon, (RETURN)=XL or XE type. If
                             Axlon, skip the next question.

     Use default config for (x)K? N=no, specify parameters. "Y" or
                             [RETURN] uses the parameters the DOS
                             generated for your type of machine. Note
                             that the "x" is replaced by the amount
                             of total memory MYDOS thinks you have.
                             Skip the next three questions if answered
                             yes.

     Size(K)?                Size of the RAMdisk area in K (8 single
                             density sectors = 1K); this must be a
                             multiple of 16 (NI 256K upgrade=192 OR 128,
                             AXLON=112, default or 130XE=64).

     Control Address(HEX)?   Address of the memory map control port: a
                             RETURN specifies $D301 for the 130XE. For
                             the AXLON RAMPOWER 128, enter "CFFF" here.

     Page sequence?          [RETURN] if using a standard Atari 130XE
                             or equivalent RAMdisk. Other standard values
                             are (1) for the Newell industries upgrade,
                             (2) for the RAMBO from ICD, and (5) for
                             Axlon or compatible boards. The most
                             general response is to list the page
                             numbers to be used as 2 hex digits each,
                             separated by commas, and continuing if
                             necessary by ending the line with a comma.
                             The sequence is ended with a "0" if the
                             RAMdisk is 130XE compatible, and
                             with a "FF" if it is Axlon compatible.

     RAM disk drive no?      Drive number used to access the RAMdisk
                             (RETURN for drive 9 or a drive number 1-9)

          A  [RETURN] does not retain the current value when responding to
     these  questions;  it  changes  the setting to a generally acceptable
     default.  Even  a  BREAK  or  RESET  will not leave the configuration
     unchanged.  If  the  configuration process is aborted for any reason,
     and  you wish to retain your old configuration, you should reboot the
     computer or properly complete the configuration before doing anything
     else.

          If  instead  of  a  [RETURN], a drive number had been specified,
     then  that drive would be reconfigured. The first question identifies
     whether  the  drive  is  to be included in system initialization (and
     thus be available for later use). If a non-existent disk is included,
     it does not cause any problems with the system: it simply causes that
     disk  to be examined each time the system is booted and reset (adding
     perhaps  a  second  to  the time it takes to boot MYDOS). If drive is
     excluded  from the system, no further questions are asked. Otherwise,
     the second question asks if the drive is configurable: that is, is it
     like  the  ATARI 810 drive (with a fixed configuration) or is it like
     the  PERCOM  or ATR8000 drives. If the disk is not configurable it is
     assumed   to  be  a  720  sector,  single  or  double  density  ATARI
     810/815/1050 disk drive.

          The third question is whether the drive is a high capacity drive
     (does  it  use the modified configuration for non-floppy disks). This
     is  for  hard  disks.  This  should be answered "N" if the drive is a
     floppy disk drive, and "Y" if otherwise. If this question is answered
     "Y", the only remaining question is the size (in sectors, from 256 to
     65535)  of  the  drive.  Drives  up  to  16 million bytes (Megabytes)
     capacity  can  used  with  MYDOS,  and  larger  drives can usually be
     partitioned  to  appear as two or more drives of less than 16 million
     bytes  capacity.  See  your  hard disk manual for more information on
     this subject.

          Drives that have not been configured can still be accessed. This
     configuration  is necessary ONLY when formatting hard disks, and when
     using  PERCOM  or ATR8000 interfaces. Other than the above, the drive
     configuration is not necessary - MYDOS will figure out by itself what
     the disk is capable of by its format.

          If  the  first three answers are "N" (do not exclude the drive),
     "Y"  (it is configurable), and "N" (it is not a high capacity drive),
     the  configuration  is asked for: Is the drive double sided, how many
     tracks  are there on the each side of the disk, and at what speed can
     it  move the read/write head across the disk (what is its step rate).
     The  first question is answered with "Y" or "N" ("Y" meaning "yes" it
     is a double sided drive, and diskettes formatted on it will be double
     sided).  The  second  question  is  answered  with  35, 40, 77, or 80
     followed  by  a  [RETURN].  If you have IBM PC/AT style high capacity
     disk  drives (1.2Mb capacity) you may use 77 of the 80 tracks in high
     capacity  mode  providing  1  Mb  capacity by selecting 77 tracks. No
     other  numbers  are  accepted.  The answer to this question specifies
     both  the type of drive (8 inch/high capacity 5 1/4 inch, or standard
     5  1/4 inch) as well as the number of tracks per side. This answer is
     very important to the operation of the drive.

          The  last  answer  ("Step  Rate?") is entered as a code: use the
     following  table and the drive specifications to determine the proper
     value:

       Code value    8 inch rate     5 1/4 inch rate
           0         3 ms/track      6 ms/track    (XF-551)
           1         6 ms/track      12 ms/track
           2         10 ms/track     20 ms/track
           3         15 ms/track     30 ms/track


     P. Diskette Density Selection

          The  density  used  for most MYDOS commands is determined by the
     data  written  on  the diskette and the operator need not worry about
     setting  it. The "P" command is provided to allow forcing the density
     setting  for  the  format  ("I")  command,  and to permit setting the
     density  for  disk  drives  and  systems  that  do  not automatically
     recognize  the  density  of  a  diskette  when  reading sector 1 (for
     example, Indus GT drives).

          Type the drive number, followed by "S" or "D" to set the density
     of the drive. Example: "2,D".


     Q. Create Subdirectories

          When  a  diskette  is formatted, an empty directory (the highest
     level  or  root  directory)  is created. This directory is capable of
     holding   up   to  64  files  or  other  directories.  If  additional
     directories  are  installed in this directory, each of the additional
     directories  can  contain  up  to 64 files as well. A subdirectory is
     installed  in  an  existing  directory  using  the  "Q"  command  and
     responding  with  the  filename of the new directory. For example, if
     "TEST"  and "BAS" are two subdirectories in the root directory of the
     diskette in drive 1, "1:TEST:COMM" or "1:BAS>COMM" would create a new
     directory   in   the   "TEST"   or  "BAS"  directories  respectively.
     "1:NEW:COMM"  would  not  create  a  directory,  however,  since  the
     directory  "NEW"  does  not  already  exist.  A  "Q" command with the
     response  "1:NEW"  would create it, however, and a second "Q" command
     with  the  response  "1:NEW:COMM" would then create the new directory
     called "COMM" within the directory "NEW".

          Each  directory  takes  up 8 sectors, and after it is created it
     may  only be referenced as a directory (followed by a ":" or ">"), or
     deleted. It may only be deleted if it is empty (if it has no files in
     it). A directory may be emptied by using the "D" (delete) command and
     specifying  the files "*.*" or "*.*/N" to remove all the files in the
     directory. You can most safely do this by specifying the full name of
     the  directory:  D5:MSGBASE>SEPT1983>*.*/N for example. Now to delete
     the  SEPT1983 subdirectory, simply delete "D5:MSGBASE>SEPT1983" (note
     no trailing ":" or ">").


     R. Set the Default Directory

          The  "R" command is used to select a directory to be used when a
     file is referenced without the drive number: that is, when file names
     such  as "TEST1.BAS" or "D:NEWCODE" or even ":BIGFILE" are used, they
     are  assumed to be in the default directory. Programs run under MYDOS
     can  access  the contents of the current default directory by using a
     file  name  of  the  form "D:..." without the drive number explicitly
     entered.  They  may also set the default directory by calling the CIO
     Function code 41 (set directory) routine.

          The  directory  is  set  by  inserting  the  diskette  with that
     directory  on  it into the desired drive, then entering the file name
     of the directory with no trailing ":" or ">".

          If the diskette in the drive containing the default directory is
     replaced,  or  if the default directory on a diskette is deleted, the
     default  should  be  redefined.  The  one exception is if the default
     directory  is  the  root  or  main  directory  on a diskette: this is
     because the root directory is at the same location on all diskettes.


     IV. THE MENU COMMANDS: The MEM.SAV feature

          Whenever  the  DOS menu is entered, MYDOS will load DUP.SYS from
     drive  1.  If DUP.SYS cannot be found on drive 1, it will look for it
     on drive 2, 3, etc... until it finds it.

          Loading DUP.SYS will overwrite a good chunk of lower memory, and
     will  wipe out the data in most languages. Here's where MEM.SAV comes
     into  play.  When  this  feature is enabled (by going to the menu and
     pressing  "N"  and  [RETURN], then "B" to exit back), the memory that
     DUP.SYS  would  overwrite  is  saved to the file "MEM.SAV" on drive 1
     (may  be drive 8 if you use one of the RAMBOOT programs on the disk).
     It  then  loads  the DUP.SYS. When you press "B" to return, or if you
     use the "N" command of the menu, MYDOS will load back in the MEM.SAV,
     thus  restoring  the  overwritten  memory. The result is your program
     remains intact.


     V. FILE MANAGER FUNCTIONS PROVIDED THROUGH CIO

          MYDOS  supports all CIO calls supported by ATARI DOS 2, with the
     following  modifications to the OPEN (Function code 3) and the FORMAT
     (Function  code  254)  functions. Three additional CIO functions have
     been  added:  MAKE  DIRECTORY (Function codes 34 & 42), SET DIRECTORY
     (Function code 41) and LOAD MEMORY (Function codes 39 & 40).

          The  OPEN function in ATARI DOS 2 does not use the data provided
     in  the  AUX2 byte, but in MYDOS when the AUX1 byte is 8 (the file is
     opened for creation or replacement), the AUX2 byte contains two flags
     that  control  the file format, and whether it will be created locked
     or not.

          If  AUX2  bit  2  is  set,  the  file will be written in MYDOS 4
     format,  and  may contain sectors beyond absolute sector 1023. Such a
     file  may not (easily) be read by DOSes other than MYDOS. This is the
     only  format used with high capacity disks. If AUX2 bit 5 is set, the
     file  will  be  written  with  the  "LOCKED" bit in the directory set
     initially.  This is provided for use by multi-tasking functions (such
     as  a  print  spooler,  sequential file pre-reading function or other
     enhancements  one  might  want  to  make  to  the  standard OS or DOS
     provided functions).

          The  FORMAT  function  in  ATARI  DOS 2 does not provide for any
     variations  to  the standard disk usage: in MYDOS the contents of the
     AUX1  and AUX2 bytes are used to specify the number of sectors on the
     disk  being  formatted, and whether the disk needs to be formatted by
     the  controller as well as needing directory initialization. Bit 7 of
     AUX1  is  set  to  skip  the  physical  formatting of the entire disk
     surface when it is not required, and bits 6-0 of AUX1 and all of AUX2
     are  used  to specify the number of sectors on the disk being created
     (if  all 15 bits are zero, the disk is assumed to be the size defined
     by  the  drive configuration). This permits formatting a single sided
     diskette  on  double sided drives, for example. Be careful when using
     this feature: it can be more trouble than it is worth.

          To  load  (and  possibly execute) a program file, MYDOS provides
     the  CIO  function 39 call.  CIO function 40 will do the same; it was
     included for compatibility with programs written for SpartaDOS.  From
     BASIC  you  can load and execute a program by executing the line: XIO
     39,  #3, 4, 0, "D:MYPROG.OBJ".  Any inactive IOCB can be used, and if
     AUX1=4 both the INIT and the RUN entries will be executed. If AUX1=5,
     the  RUN  entry  will  be executed; if AUX1=6, the INIT entry will be
     executed;  and  if  AUX1=7, the file will be loaded without executing
     either  entry  point.  Any  other values of AUX1 will return an error
     code and do nothing.

          Another  XIO call, XIO 34, has been added to create a directory.
     CIO  function  42  performs  exactly  the  same  thing,  and has been
     provided  for compatibility with programs written for SpartaDOS. When
     a  directory  is  created,  the name used must not match any existing
     file  or  directory in its parent (for example if the directory to be
     created  is  named "D1:TEST:BUGS", there can be no other directory in
     the main directory named "TEST" nor a file named "TEST" there.

          From  BASIC,  the XIO 34 call is "XIO 34, #iocb, 8, 0, dirname",
     where  "iocb" is any available unit number, and "dirname" is the name
     of the new directory (it does not end with a trailing ":" or ">").

          The final function added to those provided by ATARI DOS 2 is XIO
     41,  to  define the default directory.  The default directory is that
     which  will be searched for a file if the file name begins with "D:".
     In  ATARI  DOS 2 this default directory is always "D1:" but in MYDOS,
     the  default directory can be any root or subdirectory on any disk in
     the  system.  The  buffer address passed to CIO in the XIO 41 call is
     the  address  of  a  string that contains the default directory name,
     terminated with either an end of line ($9B) or a null byte ($00). The
     directory will be accessed before returning to the calling program so
     that  an  error in specifying the directory will be reported as early
     as possible.
