DOS 2.5 Manual
ATARI DISK OPERATING SYSTEM 2.5
Every effort has been made to ensure the accuracy of the product
documentation in this manual. However, because we are constantly improving and
updating our computer software and hardware, Atari Corp. is unable to guarantee
the accuracy of printed material after the date of publication and disclaims
liability for changes, errors, and omissions.
ATARI, ATARI BASIC, AtariWriter, 1050, 810, 130XE, 65XE, and 800XL are
trademarks or registered trademarks of Atari Corp.
No reproduction of this document or any portion of its contents is allowed
without the specific written permission of Atari Corp., Sunnyvale, CA 94086.
Copyright 1985 Atari Corp. Sunnyvale, CA 94086
INTRODUCING ATARI DOS 2.5
In an ongoing effort to provide the highest quality of
products for use with your ATARI Computer, the new ATARI
Corp. is supplying you with the enclosed DOS 2.5 Master
Diskette. Its advantages over ATARI DOS 3 include ease and
convenience of use (most utilities are contained within a
single file and need not be loaded from disk) and
compatibility with DOS 2.0S. DOS 2.5 also allows you to use
the full capacity of your ATARI 1050 Disk Drive and to access
the full RAM potential of the ATARI 130 XE.
This short manual provides you with instructions for getting
started with DOS 2.5. For complete information on DOS 2.5,
including detailed discussions on the menu items,
compatibility with DOS 3 and 2.0S, the RamDisk, and the 2.5
Utilities, you may consider obtaining the new ATARI DOS 2.5
Manual. Available from ATARI Customer Relations, P.O. Box
61657, Sunnyvale, CA 94088. Cost: $10 plus $2.50 for
shipping and handling. California residents add 6.5% tax.
Please write ATARI DOS 2.5 Manual on the outside of your
envelope when you order the book.
Getting Started With DOS 2.5
DOS 2.5 allows you to format diskettes and store information
in either single or enhanced density. With enhanced density
you can record about 50 percent more data on each diskette
than you can with DOS 2.0S. Enhanced-density storage is only
possible if you have an ATARI 1050 Disk Drive; the 810 Disk
Drive is not capable of formatting or managing data stored in
enhanced density. You need a 1050 Disk Drive to begin
working with DOS 2.5 because your DOS 2.5 Master Diskette is
recorded in enhanced density. If you often use an 810 Disk
Drive to access your files, you may want to format all your
diskettes in single density.
DOS 2.5 works with any cartridge-based program that runs on
your Atari Computer and uses DOS–even programs that predate
DOS 2.5, including the AtariWriter word processor and ATARI
BASIC. With such programs you can always use DOS 2.5 instead
of DOS 2.0S to prepare data diskettes and manage files.
Many diskette-based programs designed for use with the
earlier DOS 2.0S can also be used with DOS 2.5. However, you
may have to continue to use DOS 2.0S with certain protected
diskette programs (see your program user’s manual if you are
unsure whether a program is protected.)
THE DOS MENU
Load DOS into your ATARI Computer using the same procedures
you use for either DOS 3 or DOS 2.0S. (If you have an ATARI
130XE, 65XE, or 800XL with built-in BASIC, type DOS and press
[RETURN] to go from BASIC to DOS). The DOS Menu on your TV
or monitor screen presents a list of the DOS 2.5 options.
The prompt below the menu invites you to make a selection.
You choose the function you want to use by pressing the
letter corresponding to your selection and pressing [RETURN].
DOS then asks you for the information it needs to proceed.
Summary of DOS 2.5 Menu Options
If you have used DOS 2.0S, you will be familiar with most
options. Note the change in Option J, and the new Option P.
If you have only used DOS 3, read this section for an
introduction to DOS functions.
A. DISK DIRECTORY Allows you to call up a complete or
selective list of the files on a diskette, showing the
filenames, extenders (if any), the number of sectors
allocated to each file, and the number of free sectors still
available on the diskette.
B. RUN CARTRIDGE (Can ONLY be used with built-in BASIC or
with a cartridge installed in the computer). This option
allows you to return control of your system to built-in BASIC
or to the cartridge inserted in the cartridge slot.
C. COPY FILE For use when you have two or more disk drives
and you want to copy files from one diskette to another.
Also use this option to copy a file on the same diskette,
assigning a different name to the copy.
D. DELETE FILES Lets you erase a file from a diskette,
increasing the available space on a diskette.
E. RENAME FILE Use when you want to change the name of a
F. LOCK FILE Can be used to prevent you from changing,
renaming, or accidentally erasing a file. You will still be
able to read the file, but will not be able to write to it.
An asterisk is placed in front of the filename in the
directory to indicate that the file is locked.
G. UNLOCK FILE This removes the asterisk in front of the
filename and allows you to make changes to the file, rename
it, or delete it.
H. WRITE DOS FILES Lets you add the DOS files (DOS.SYS and
DUP.SYS) on your Master Diskette or System Diskette to a
diskette in any disk drive.
I. FORMAT DISK Used to format a blank diskette, which is
necessary before you can record any information on it. Be
sure you do not have any files you want to keep on a diskette
before formatting it. This option will format a diskette in
enhanced density provided you are using a 1050 Disk Drive;
otherwise, it will format in single density.
J. DUPLICATE DISK Use when you want to create an exact
duplicate of a diskette. This option will automatically
format the destination disk.
K. BINARY SAVE Saves the contents of specified memory
locations on a diskette.
L. BINARY LOAD Lets you retrieve an object file from
M. RUN AT ADDRESS Use to enter the hexadecimal starting
address of an object program after it has been loaded into
RAM with BINARY LOAD.
N. CREATE MEM.SAV Reserves space on a diskette for the
program in RAM to be stored while the DUP.SYS file is being
used. For some applications like programming, it is a good
idea to create a MEM.SAV file on each new diskette you intend
to use as a System Diskette. As you become more familiar
with DOS, you may find there are cases where a MEM.SAV file
serves no useful function. The inconvenience of waiting for
MEM.SAV to load into memory may warrant deleting it from the
O. DUPLICATE FILE Copies a file from one diskette to another,
even if you have only a single disk drive.
F. FORMAT SINGLE Formats a diskette in single density using a
1050 Disk Drive.
DOS 2.5 AND THE ATARI 130XE RAMDISK
The ATARI 130XE Computer is equipped with 131,072
bytes–128K– of Random Access Memory (RAM), twice the
maximum 64K available with earlier model ATARI Computers.
The additional 64K RAM can be useful for many purposes: fast
exchange of screen images for animation, additional storage
for large data bases, and so forth.
You can also use the extra RAM of the 130XE as a very fast
“virtual” disk drive. Set up as a “RamDisk”–recognized by
DOS 2.5 as Drive 8 in your system–it can accommodate up to
the equivalent of 499 sectors on a diskette. That is about
half what you can store on a diskette formated in enhanced
The “storage” capacity offered by the RamDisk is volatile
memory. Information stored in it will be lost when you turn
off your computer system. So before turning off your system,
be sure that any data currently in the RamDisk that you want
to save permanently is recorded on an actual diskette.
The RamDisk can be a very convenient tool. It allows you to
switch almost instantaneously between BASIC (or any other
programming language) and DOS, and back again. Use it to
work with files “stored” on Drive 8–a technique that might
prove especially useful when you are transferring large
amounts of data between two programs that are chained
together (that is, when one program RUNs the other).
To Activate the RamDisk
Your DOS 2.5 Master Diskette contains a file called
RAMDISK.COM that automatically sets up the extra 64K RAM of
the 130XE as a RamDisk.
When you boot your 130XE system with a DOS 2.5 Master or
System Diskette containing RAMDISK.COM, DOS will:
– Display a message that it is initializing the RamDisk;
– Set up your computer’s extra 64K of memory to act very much
as a disk drive, telling DOS to regard it as Drive 8; and
– Copy the DOS file DUP.SYS and establish MEM.SAV on the
RamDisk, and use the versions of these files on the RamDisk
rather than those on your Master Diskette.
If you wish to expand the usable capacity of your RamDisk,
you may recover the memory used by DUP.SYS and MEM.SAV by:
– Changing the contents of location 5439 ($153F) to ATASCII 1
— for example, POKE 5439,ASC(“1”); and
– Deleting the files DUP.SYS and MEM.SAV from the “diskette”
in Drive 8–that is, the RamDisk. Use option D., DELETE
FILE(S), on the DOS Menu and enter D8:*.* in response to the
DELETE FILESPEC prompt.
Note: Booting a disk which doesn’t contain DUP.SYS will cause
RAMDISK.COM to initialize the RamDisk, but DUP.SYS and
MEM.SAV will not be moved to the RamDisk.
Using DOS With the RamDisk
Because of the size of the RamDisk, you may not use DOS Menu
option J., DUPLICATE DISK, to copy either a single-density or
enhanced-density diskette to the RamDisk. Instead, you must
copy individual files, taking care that they do not exceed in
size the capacity of the RamDisk. You can ask DOS to
duplicate the contents of the RamDisk on an actual diskette.
From then on, however, that diskette will be capable under
DOS of accessing only 499 sectors worth of data–though you
can always duplicate its contents back to the RamDisk.
If You Do Not Want to Use the RamDisk
If you do not want to use the ATARI 130XE RamDisk, you can
either delete or rename the RAMDISK.COM file on your DOS 2.5
Master or System Diskette. You may then use the extra RAM
for other purposes.
If you have applications for which you do not wish to use the
RamDisk, it is recommended that you leave the RAMDISK.COM
file intact on your DOS 2.5 Master Diskette. You might wish
to make one working copy of DOS (System Diskette) that
contains RAMDISK.COM, and one that does not. Or you can
simply rename the RAMDISK.COM file on your System Diskette,
then rename it back to RAMDISK.COM when you wish to use it.
THE DOS 2.5 DISK UTILITIES
Your DOS 2.5 Master Diskette contains three new utility
programs in addition to the standard disk utilities handled
by the DUP.SYS file–those available from the DOS Menu. The
programs, each of which appears on the disk directory with a
.COM extender, function as follows:
COPY32.COM allows you to copy files from diskettes formatted
and written to from ATARI DOS 3 to DOS 2.5 diskettes,
converting the files in the process from DOS 3 to DOS 2.5.
DISKFIX.COM allows you to correct some problems that may
occur with files on DOS 2.5 and 2.0S diskettes. Under
certain conditions, you can also use this utility to recover
SETUP.COM allows you to change certain DOS parameters. You
can also use it to create an AUTORUN.SYS file that will
automatically load and run a BASIC program when you boot your
Note: RAMDISK.COM is not a disk utility. It is used only to
set up the RamDisk on a 130XE Computer.
Selecting and Loading a Utility
All three utilities are binary files that are loaded and run
using option L., BINARY LOAD, from the DOS 2.5 Menu. For
example, to begin using the COPY32.COM program, with the DOS
2.5 Menu on your screen, you would type L and press [RETURN].
For more detailed instructions for the latter two utilities,
consult the ATARI DOS 2.5 Manual (see the Getting Started
section of this manual for ordering instructions).
Using this utility is much like using the COPY FILE function
on the DOS Menu. After you load the COPY32.COM program, you
are prompted to specify which drive will hold your DOS 3
(source) disk and which drive will hold your DOS 2.5
(destination) disk. If you have only one drive, type 1 in
response to both prompts. In this case, you will have to
swap your DOS 3 and DOS 2.5 diskettes during the copying
process. If you have more than one disk drive, you may
select one to hold your DOS 3 diskette and another to hold
your DOS 2.5 diskette.
At this point, if you have only one drive, the utility
prompts you to insert your DOS 3 disk in Drive 1. For safety,
place a write-protect tab on your DOS 3 disk so that you will
not erase valuable data if you make an error while swapping
If you specified two different drives, the utility prompts
you to insert both your DOS 3 and DOS 2.5 disks.
After you insert the diskette or diskettes, press [START].
The COPY32.COM program reads the directory of the DOS 3
diskette an` displays the files it contains, sixteen at a
time, by number. Press [RETURN] to see the next sixteen
files. When all the files on the diskette have been listed,
you have the options to restart, return to DOS, or view the
To convert a file, enter the number of the file you wish to
convert. The utility prompts you to confirm your choice by
When you press [START], the program begins the conversion
process by reading the specified file from the DOS 3
diskette. After COPY32.COM reads the entire file (or as much
data as it can accommodate in its memory buffer), it asks you
to swap disks if you specified the same drive for your DOS 3
and DOS 2.5 disks. With very large files, you may have to
swap diskettes several times. If you are using two drives,
the program copies and converts the file in a single
After the file has been copied and converted, press [START]
to return to the listing of files on your DOS 3 diskette,
from which you may choose another file to convert.
If an error occurs during the copy process, COPY32.COM
displays an error number and prompts you press [START] to
restart, or [SELECT] to return to the DOS 2.5 menu.
Note: Unless you have two disk drives, you will be unable to
convert files of more than 124,700 bytes (300 bytes less than
the maximum file length possible under DOS 2.5).
This program begins by showing you the current drive number
and a menu with these five options:
1. Change Drive #
2. Unerase File
3. Verify Disk
4. Rename File by #
5. Quit to DOS
Type the number of the function you wish to use but do not
press [RETURN] after typing your choice. After activating an
option, follow the prompts.
This program begins by showing you a menu with these four
1. Change current drive number
2. Change system configuration
3. Set up an AUTORUN for Boot
0. Quit – Return to DOS
Menu selections 1 and 0 are used for “housekeeping” purposes.
The two main functions of this utility are menu selections 2
and 3. Press the number key that corresponds to the function
you wish to use, then follow the prompts.
Atari Corp. welcomes any questions you might have about your
Atari Computer product.
Atari Customer Relations
P.O. Box 61657
Sunnyvale, CA 94088
Please write the subject of your letter on the outside of the
We suggest that you contact your local Atari User Group.
They are outstanding sources of information on how to get the
most out of your Atari Computer. To receive a list of the
user groups in your area, send a self-addressed stamped
Atari User Group List
P.O. Box 61657
Sunnyvale, CA 94088