DOS stands for Disk Operating System. In general terms, DOS is
a command line interface (CLI) OS to manage data in disks. This
means that any OS that allows the user to access and manage data
in disks is a DOS whether that DOS is compatible with others or
The most important versions of DOS because of sales and use
have been PC DOS
(Digital Research) and FreeDOS
(developed by Jim Hall).
What we have been accustomed to as the first is DOS
as the CLI OS for the IBM Personal Computer and clones written by
Tim Paterson (86-DOS) and then sold by Microsoft, on which
Windows was later built on.
Although IBM originally used the same acronym in the early
1970s for their disk operating system for IBM System/360, the
1970s version of DOS (later replaced by VSE) is not the
same as what we commonly know as DOS for IBM PC and clones.
In computer science, many terms are confusing and DOS is one
of them. If it is spelled DoS (lower case `o`),
we refer to denial of service. In this page, I am covering DOS
(all upper case).
To make matters ever more confusing, one of the biggest
misconceptions nowadays is that many think that DOS is MS-DOS
In the early 1980s Microsoft bought the source code for 86-DOS
(commonly referred to Quick and Dirty Operating System, QDOS),
which was developed by Tim Paterson for the Intel 8086
microprocessor, for Seattle Computer Products (SCP). 86-DOS
contained about 4,000 lines of assembly. QDOS later became PC DOS
for the IBM Personal Computer system on August 1981. DOS was not
developed originally by Microsoft and Bill Gates (in his book
The Road Ahead, 1995)
recognizes Tim Paterson as the father of DOS. Although
Microsoft's version of DOS (MS-DOS) has
become obsolete, many DOS clones and OS that can interpret DOS
exist and are commonly used.
Nowadays, what is left of MS-DOS is
reduced to a handful of files buried in
C:\WINDOWS\COMMAND in Windows
9x, C:\WINNT\SYSTEM32 in Windows NT 4 or
C:\WINDOWS\SYSTEM32 in Windows
NT 5 (XP) and up — not to be confused with PowerShell
(C:\WINDOWS\SYSTEM32\WINDOW~1\V1.0). I would like to see
DOS included back in Windows as a
stand-alone OS (similar to what macOS did with
Unix). Worse of all, Windows NT 4 and up use an
emulation of MS-DOS 5.0
(1991) — not 6.0 (1993) or 6.21/6.22 (1994) — that makes our life
hell when trying to work with old DOS commands and batches. Some
of these commands do not work anymore or exist anymore. Microsoft
forces users to use the less effective Windows 4.xx versions of
programs that were reliable in DOS.
MS-DOS as a
stand-alone OS (less than 5 MB in MS-DOS 6.22)
has not been marketed by Microsoft, since 1994. Microsoft opted
to concentrate on the Windows
graphical OS project in 1983 (marketed against Steve Jobs' Apple
DOS originally included
BASIC, which later became
QuickBASIC and then
Nowadays, Microsoft does not include any programming language by
QBASIC.EXE has to be copied from
D:\OTHER\OLDMSSDOS to C:\WINDOWS\COMMAND.
DOS Shell (230 KB) was last included in MS-DOS 6.2.
Amazingly DOS Shell (PC DOS) was
dropped around the same time.
The D:\OTHER\OLDMSSDOS (Old MS-DOS)
directory on the Windows 95/98
disk has 17 files. Note that D: is your CD-ROM drive and
that there is no TREE, just DELTREE. See
Maybe you can get your hands on any used copy of MS-DOS 5.0
(1991) or MS-DOS
6.22 (1994). Be careful since Microsoft might consider the
latter activity illegal. You can download free of charge and use
Installing MS-DOS on i386 & i486
This technique is different from what most nowadays books
indicate, using FAT16. The only drawback of installing FAT16 DOS
is that the HDD has to be divided into partitions not larger than
2 GB each (seen by the system as separate disks). The first
partition is primary and the rest are logical partitions.
You can also use a RAM drive (RAMDRIVE.SYS), which
will increase memory performance similar to paging. Since it is
not a physical disk, you should not save anything on it that you
really want to save.
These instructions cover MS-DOS only
although they might also apply to DOS clones. Reference to
PC DOS 2000
is supplied. Unfortunately I do not have experience on other
versions of DOS like DR-DOS 7.03
(only 3.13 MB, 3 floppies), which is differently and not normally
taught in schools.
The installation procedure, explained in this site, is
different from what most books might tell you. Both
CONFIG.SYS and AUTOEXEC.BAT are changed. RAM is
improved. By using this technique, a DOS and Windows set-up would work almost
as well as /swap in Unix.
Run FDISK.EXE from the boot disk.
View old partitions, if any, and delete them.
Delete first non-DOS partitions, then logical, then extended
and finally the primary (if any).
Make primary partition. Since MS-DOS has a
FAT16 architecture, MS-DOS cannot
read more than 2 GB at a time.
Make secondary partitions (less than 2 GB). On the secondary
partition, make logical partitions if needed. If the logical
partition is close or over 2 GB, make 1 GB partitions. Then
FORMAT each partition.
Make sure CONFIG.SYS recognizes as many logical
partitions as you need. The total number cannot exceed 26 logical
partitions (one for each letter of the English alphabet). Each
partition will be assigned a letter by MS-DOS.
Create backup files (.BAK) of CONFIG.SYS and
AUTOEXEC.BAT before doing changes. Should there be a
problem while booting, change CONFIG.BAK and
AUTOEXEC.BAK back to CONFIG.SYS and
AUTOEXEC.BAT accordingly. It is better to be safe than
Open CONFIG.SYS and AUTOEXEC.BAT with
EDIT on MS-DOS or
E on PC DOS. Then
save them with the new names.
You may also copy them to new files with different names, of
At this point, you can create the RAM drive (or virtual disk)
that I mentioned before.
DEVICEHIGH=C:\WINDOWS\RAMDRIVE.SYS 2048 /E
Do changes on CONFIG.SYS by adding the following
lines to mount a CD-ROM in MS-DOS.
Then edit AUTOEXEC.BAT.
Copy AOATAPI.SYS to the HDD from MS-DOS. Both
CONFIG.SYS and AUTOEXEC.BAT need this file, so
copy it to your HDD.
A:\COPY AOATAPI.SYS C:
Run MEMMAKER (MS-DOS 6.x)
to optimize memory management in MS-DOS.
PC DOS does
not have MEMMAKER, but rather RAMBOOST, which
does a similar job, including EMM386.EXE to simulate
Reboot system pressing F8, which will let you confirm
each step of the CONFIG.SYS and AUTOEXEC.BAT.
If there is a problem, reboot system pressing F5
bypassing CONFIG.SYS and AUTOEXEC.BAT. Change
CONFIG.BAK and AUTOEXEC.BAK to
CONFIG.SYS and AUTOEXEC.BAT. Repeat
instructions or throw these instructions away. Either way, it is
still a fun learning experience.
Make sure the BIOS will read CD-ROM first. Follow instructions
provided by the computer manufacturer.
Reboot system with the Windows
CD-ROM or 3.5 floppies. If you are installing Windows 3.1 on an i386 or i486
PC, check out the Calmira
Depending on your needs, you might need to
connect the system to a network (internet or LAN, most likely) or
not. If you do, you need to load to memory the correct packet
driver for the network interface card (NIC) on boot. Note that
the packet driver is a .COM file ending on
PD (for packet driver). Add the
following line to AUTOEXEC.BAT replacing
FOOBARPD.COM with the correct packet driver
LH FOOBARPD.COM 0X60 5 0X300
In the example above, the first parameter (0X60) sets
the interrupt. The second one (5) sets the IRQ and the
last one (0X300) sets the I/O port.
Maintaining a Hard Drive Running MS-DOS &
I have put together a batch file (set of organized commands),
which will DEFRAG and SCANDISK your HDD. The
batch is compatible with i386 clones with DOS like FreeDOS.
Keep in mind that you can only run the batch in MS-DOS, not
If you do not want to see the DOS commands while the batch
file is running, edit the batch turning ECHO off.
All files are randomly saved on your HDD. A practical way to
manage your HDD would be having all parts that form a file
together. DEFRAG organizes files fully (/F),
defragments (defrags) files leaving space between them
(/U), sorts them by extensions (/SE) and skips
using extended or upper memory (/SKIPHIGH).
DEFRAG /F/U/SE/SKIPHIGH C:
SCANDISK repairs problems that your all disks may
have automatically without prompting (asking), deletes errors,
skips summary and checks the surface the disk. This line of code
might not work with other distributions of DOS.
The batch creates (if not already created) and assigns
C:\TEMP as the temporary directory instead of using
C:\DOS or C:\WINDOWS as a temporary directory.
Some programs delete the temporary directories after
installation. This would be serious trouble if the installation
routine deleted the C:\DOS directory.
IF NOT EXIST C:\TEMP MKDIR C:\TEMP
If you are running Microsoft Office 6.0 or earlier, you might
want to delete all temporary files, which start with a tilde
DEL C:\~*.* /F/S/Q/A:R/A:H/A:S/A:A
Note that using the recursive switch (/S) in
DEL tells the system to delete a certain criteria (in
this example, ~*.*) in all subdirectories from a
specific starting point, (in this example, C:, meaning
the whole drive).
To delete any temporary files created by other programs,
delete by force the contents of the C:\TEMP directory
and all subdirectories without being prompted to confirm
deletion, regardless of their attributes.
DEL C:\TEMP\*.* /F/S/Q/A:R/A:H/A:S/A:A
If you want to generate a log of the deletions, send the
output to text file (for this example, FOO.TXT). In the
example below, the system will first write the date
(%DATE%) and time (%TIME%) when the batch is
run and two blank lines (ECHO., including the period
after ECHO) after the log has been generated for
cosmetic purposes. As such, these blank lines can be
ECHO %DATE% %TIME% > FOO.TXT
DEL C:\~*.* /F/S/Q/A:R/A:H/A:S/A:A > FOO.TXT
DEL C:\TEMP\*.* /F/S/Q/A:R/A:H/A:S/A:A > FOO.TXT
ECHO. > FOO.TXT
ECHO. > FOO.TXT
Putting all the commands together, your batch file would look
as the sample below.
Note that is good practice to leave blank lines between
sections of a batch file to make it easier to read. These lines
do not affect the functionality of the batch file (no speed
increase or delay). Therefore the sample above is the same as the
one below, but the one below is easier on the eyes.
Of course, follow this instructions at your own risk. Although
these commands will not normally hurt your system, do
NOT blame me as I take no responsibility if
something goes wrong and/or if you delete important data by
mistake. Refer to the disclaimer.
As I mentioned at the beginning of this section, these
instructions are for MS-DOS. Other
versions of DOS are slightly different. For example, FreeDOS has
a more organized directory structure and comes with
C:\FDOS\TEMP where FDOS is the DOS
subdirectory. I do not know if FreeDOS has
a built-in facility for garbage management. If you were to adapt
the previous code, make sure you understand the directory
structure of the version of DOS as well as which commands and
executables are available.
an alternative to MS-DOS and
during the DOS heyday in the 1980s. It has changed owners in
the past two decades from Digital Research (DR) to Novel as
Novel DOS (1991), to Caldera as OpenDOS (1996), to DeviceLogics
once again as DR-DOS
(2002). Since its last incarnation, DR-DOS/OpenDOS
Enhancement Project was started as a community initiative to
keep its open
source up to date with technology.
FreeDOS (Jim Hall)
FreeDOS by Jim Hall is an x86
clone based on DOS-C (1994) by Pat Villani that can
"reproduce the functionality of MS-DOS.".
The directory structure of FreeDOS is
based on Linux and all content of the OS is
located in C:\FDOS including the TEMP
subdirectory (C:\FDOS\TEMP, which is different from
the path that I have used since I learned to work with MS-DOS.
Within modern DOS clones, FreeDOS
seems to be the most popular, robust and most user-friendly
choice. As a matter of fact, it is my DOS of choice especially
since Jim Hall is very accessible for questions and
continuously makes video tutorials on his OS.
To install software, you can use FDIMPLES to access
its repository. To establishing network connections,
FDNET.BAT handles a vanilla packet
MSX-DOS was a version of DOS developed by Microsoft in 1984
for MSX systems, which combined MS-DOS 1.0
New-DOS (not to be confused with NEWDOS or NewDOS) is
clone in German with command line tools via built-in menus and
even a built-in text-only web browser.
NewDOS (not to be confused with New-DOS or NEWDOS) is
NEWDOS (NewDOS or NEWDOS+>; not to be confused with
New-DOS or NewDOS) was designed for TRS-80 series of computers.
NTFSDOS developed by System Internals (Winternals) allowed
users see NTFS partitions (NT
4/5 encrypted partitions) as regular DOS FAT16 partitions.
To no one's surprise, if NTFSDOS could break Microsoft's
encryption in order to access a drive as plain DOS, Microsoft
was bound to acquire it and remove it from the market
NX-DOS is an x32 16-bit/32-bit MS-DOS
clone that uses RX-DOS memory management.
DOS is made by IBM. It is more reliable than Microsoft's
latest commercial version (MS-DOS
6.22). IBM indicates that PC DOS 2000 can give users an
additional 40 KB of free disk space. There is further
information on PC DOS 7.
Also refer to the batch to maintain your HDD running on MS-DOS or
PTS-DOS "is a powerful and fastest DOS with a simple
graphical file manager and FAT32 architecture. PhystechSoft
also has distribution."
ROM-DOS includes Borland SDK and is "much more than an
inexpensive replacement for MS-DOS,
designed for embedded and mobile computing environments"
with access to FAT32.
Apple DOS was Apple's OS for Apple II (1977). It was
replaced by ProDOS (1983), related to Sophisticated Operating
System (SOS) (1980).
Atari DOS was the OS for Atari 8-bit home computers
(1979-1982). Various versions were available in the market by
Commodore DOS (CBM DOS) was a beast of its own running from
ROM for the MOS 6502 family of chipsets — from PET (1977) to
C128 (1985). The most commonly used version was 2.0 that came
in the C64.
DOS/VSE is "DOS then DOS/VS then DOS/VSE then VSE/SP
then VSE/ESA (current) mainframe OS from 1964 till today
[which] has its own half dozen file systems neither FAT16/FAT32
nor NTFS, not Linux compatible"
RX-DOS (with only eight files)
supports FAT12, FAT16 and FAT32. RX-DOS does not support
Windows and may support
Linux. The OS has some bugs.
4DOS was a MS-DOS 5.0
emulator and COMMAND.COM replacement by JP Software. Nowadays the vendor markets its
CMD.EXE replacement for Windows NT named Take Command
DOSBox is a MS-DOS 5.0
emulator released in 2002 for BeOS (Haiku nowadays) FreeBSD,
OS/2, RISC OS, Solaris and especially Windows. Since its source code
is available to install DOSBox. In
theory, it can be ported to any OS. Since old DOS programs
(even those written by Microsoft) may not run properly or at
all in new versions of Windows,
DOSBox is a
practical tool, not only to run DOS games (not limited to
abandonware) as marketed by the developers.
Note that this emulator runs from the Z: virtual
disk (virtual disk) as seen below.
In order to access any files system, DOSBox
needs the directories to be mounted in order to access them
(similar to Unix).
MOUNT X X:\GAMES
The latter command can be added after the line
[autoexec] in the DOSBOX.CONF, which serves
as both CONFIG.SYS and AUTOEXEC.BAT. Whether
mounting the subdirectory every time you need it or calling it
at that point, go to the new virtual disk (X:) in
order to access the contents of the mounted directory
(X:\GAMES) as normally done in most DOS versions.
Just as with a real AUTOEXEC.BAT, the
[autoexec] section in the DOSBox.CONF
file, you can call commands turning ECHO off.
MOUNT X X:\GAMES
The latter was quoted from the output of the HELP
DOSEMU is a command prompt emulator "and
is a Linux application that enables Linux to run many DOS programs — including
some DPMI [DOS Protected Mode Interface applications]" as
per the project developers.
DOSEMU "uses FreeDOS as
the default DOS". Therefore it comes with the FreeCOM
shell, a replacement for COMMAND.COM.
DOSEMU mounts A: to access the floppy (B:
reserved for second floppy), C: to access the DOSEMU
environment acting as the OS including programs you install
like OpenGEM in my example, D: to access the Linux home directory (~\),
E: to access the CD-ROM, Z: where DOSEMU and
all its commands reside.
The following was quoted from help.
XTM PC Emulator
XTM PC Emulator is
"a software emulation of a classic PC/XT computer [PC DOS 3.0]
for EPOC32." Within this standard application for your
portable computer, you can run any software which would run on
a low-end PC clones from the 1980s.
Graphic User Interfaces for MS-DOS Other Than
Since nowadays most of us are used to some GUI or
another, a good idea is installing OpenGEM (an modern and
version of GEM), which is based on FreeGEM, which is based on
Graphical Environment Manager (GEM), on MS-DOS or
any compatible clone like FreeDOS.
If you decide to do this on DOSBox,
keep in mind that the installation path should be on
C:. You would need the path where you want to mount
OpenGEM to be installed.
MOUNT C X:\OpenGEM
Once installed, GEM.BAT can be ran from the
C: virtual disk. As mentioned before, you can edit
to mount the location of the GEM.BAT as C:
(unsure if it could run properly if mounted using a different
letter). You can even call GEM.BAT to make OpenGEM run
automatically, but image guess that would take the fun out of
There was a SourceForge project named BlueGEM on SourceForge
that combined FreeDOS
with FreeGEM in one package for DOS gamers. It was a great idea
to revive many old i386 and i486 PCs. The installations was be
done from a floppy so you had to mount the of the directory
containing the installation files to A:.
MOUNT A X:\[path]
Then run the INSTALL.APP, which calls
INSTALL.TXT to copy the installation files
Note that applications in GEM (FreeGEM and OpenGEM) are
.APP files — not DOS or Windows.EXE or
Using the example above, on Linux, I
running OpenGEM, various applications from the OpenGEM SDK and
ZSNES for DOS. I do not think there is anything practical doing
this, but it is sure fun to see old technology originally
written several decades ago running on new hardware. It is
merely an excuse to show off. After all, ZSNES is also
available on Linux.
Note that, on Windows, you
can run the PortableApps.com
port of DOSBox
making it ready from a USB flash drive with any added software
and/or your personalized configuration.