DOS stands for Disk Operating System. DOS is a command line interface operating system for IBM Personal Computer systems and clones. Although IBM originally used the acronym DOS in the early 1970’s for their disk operating system for the 360 series computers, the 1970's version of DOS (later replaced by VSE) is not the same as what we commonly know as DOS. In the computer science, may terms are confusing and the use of the name DOS is one of them.

In the early 1980's Microsoft bought the code for 86-DOS (commonly referred to QDOS), which was developed by Tim Paterson for the Intel 8086 processor, for Seattle Computer Products. 86-DOS is commonly referred to as Quick and Dirty Operating System (QDOS), which contained about 4,000 lines of assembly language code. 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 operating systems that can interpret DOS exist and are commonly used.

What is left of MS-DOS is hidden in C:\WINDOWS\COMMAND in Windows 9x, C:\WINNT\SYSTEM32 in Windows NT 4 or C:\WINDOWS\SYSTEM32 in Windows NT 5 (XP) and many of its files were deleted. I would like to see DOS included back in Windows as a stand alone system (similar to what Mac OS X did with Unix). Worse of all, Windows NT 4 and 5.1(XP) use an emulation of DOS 5.0 that makes our life hell when trying to work with old DOS commands and batches. Some of 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 system (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 operating system project in 1983 (marketed against Steve Jobs' Apple Macintosh, 1984).

DOS originally included BASIC, which later became QBASIC (Quick Basic). Nowadays, Microsoft does not include any programming language by default. QBASIC has to be copied from the CD-ROM (D:\OTHER\OLDMSSDOS) to C:\WINDOWS\COMMAND.

DOS Shell (230 KB) was last included in MS-DOS 6.2. Amazingly PC-DOS Shell from 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 command, just DELTREE. See directory.

Windows 3.1 was the last version running as a system program running on the MS-DOS operating system. The MS-DOS operating system is the foundation of Windows 4.x. Windows NT 4 and 5 are based on a different kernel and its CMD.EXE file merely emulates DOS 5.0.

Maybe you can get your hands on any used copy of DOS 5.00 (around 1991) or DOS 6.22 (1994). Be careful since Microsoft might consider the latter activity illegal. You can download free of charge and use FreeDOS.

Other Versions of DOS Compatible with MS-DOS:

PC-DOS 2000 (also known as PC-DOS 7) is made by IBM as PC-DOS 2000. Since stores do not stock it, you must buy it directly from IBM for $60 (at press time). PC-DOS 2000 (IBM's fifteenth version of the operating system, including fixes, while still being FAT 16) is more reliable than Microsoft's last 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. Read what I found on PC-DOS 6.3. Also refer to the batch file to maintain your hard drive running on PC-DOS.

XTM PC Emulator is "a software emulation of a classic PC/XT computer [PC-DOS 3.0] for the EPOC32 operating system." Within this standard application for your handheld computer, you can run any software which would run on a low-end PC clone from the 1980's.

NTFSDOS developed by Sysinternals (System Internals) lets user see NTFS partitions (NT 4/5 encrypted partitions) as regular DOS FAT 16 partitions.

FreeDOS is an open source operating system (like Linux) that can "reproduce the functionality of MS-DOS".

DOS C (81 KB) was written as a MS-DOS clone.

DR-DOS 7.03 has changed owners in the past decade or so (Digital Research, then Novell, then Caldera, then and now DeviceLogics). The current version is marketed as embedded solution.

New DOS has command-line tools via built-in menus and even a built-in text-only web browser.

ROM DOS includes Borland Tools 5.2 and is "much more than an inexpensive replacement for MS-DOS, designed for embedded and mobile computing environments".

PTS DOS 2000 Pro, developed by Paragon Software (a Russian and German project), "is a powerful and fastest DOS" with a simple graphical File Manager and FAT32 architecture. PhystechSoft also has distribution."

DOS Non-Compatible With MS-DOS:

DOS/VSE is "DOS then DOS/VS then DOS/VSE then VSE/SP then VSE/ESA (current) mainframe operating systems from 1964 till today [which] has its own half dozen files systems neither FAT nor 16/32 nor NTFS, not Linux compatible" (thanks Pete).

RX-DOS (with only eight files) supports FAT-12, FAT-16 and FAT-32. RX-DOS does not support Windows and may support Linux. The operating system has some bugs.

DOSEMU is "for DOS Emulation, and is a Linux application that enables the Linux operating system to run many DOS programs - including some DPMI [applications]."

SuperDOS is not for stand alone systems. It is only designed to do business transaction processing.

MS-DOS Installation Instructions for 386 & 486 Systems:

This technique is different from what most nowadays books indicate, using FAT 16. The only drawback of installing FAT 16 DOS is that the hard drive has be divided into 2 GB partitions (seen by the system as separate drives). The first drive is primary and the rest are logical drives.

You can also use a RAM drive. This virtual drive (RAMDRIVE.SYS) will increase the performance of the RAM. Since it is not a physical drive, you should not save anything on it that you really want to keep.

These instructions cover MS-DOS only. Reference to PC-DOS 2000 is supplied. Unfortunately I do not have data on other versions of DOS as FreeDOS and DR-DOS 7.03 (only 3.13 MB, 3 floppies), which behave differently and are not normally taught at college.

The installation procedure, explained in this site, is different from what most books might tell you. Both CONFIG.SYS and AUTOEXEC.BAT files are changed. The memory (RAM) is improved. By using this technique, DOS and Windows environment would work as well as Unix.

Run FDISK from the bootable disk.

a:\fdisk

View old partitions if any and delete old partitions.

Delete first non-DOS partitions, then logical, then extended and finally the primary (if any).

Make primary partition. Since MS-DOS has a FAT 16 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.

Format each partition.

a:\format c:
a:\format d:
a:\format e:

Install MS DOS 6.22 (PC-DOS 7 or 2000) on the HDD.

Make sure CONFIG.SYS recognizes as many logical drives as you need. The total number cannot exceed 26 logical drives. Each drive will be assigned a letter by MS-DOS.

lastdrive=z

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. It is better to be safe than sorry.

Open CONFIG.SYS and AUTOEXEC.BAT with EDIT on MS-DOS or E (which stands for EDITOR) on PC-DOS.

c:\edit
c:\e

Do changes on CONFIG.SYS by adding the following lines to use CD-ROM in MS-DOS.

devicehigh=c:\dos\aoatapi.sys/d:idecd000/q

You can also create a RAM drive (or virtual disk).

devicehigh=c:\windows\ramdrive.sys 2048 /e

Do changes on AUTOEXEC.BAT by adding the following lines to load CD-ROM driver.

lh= c:\dos\mscdex.exe/D:idecd000

Copy AOATAPI.SYS to HDD from MS-DOS bootable disk. Both CONFIG.SYS and AUTOEXEC.BAT need this file, so copy it to your hard disk.

a:\copy aoatapi.sys c:

Run MEMMAKER (MS-DOS 6.x) to optimize memory on MS-DOS. PC-DOS does not have this file. PC-DOS has RAMBOOST, which does a similar job, including the EMM386.EXE function (simulating expanded memory).

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 files. 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 maker.

Reboot system with the Windows CD-ROM or 3.5 floppies. If you are installing Windows 3.1 on your 386 or 486 PC, check out the Calmira shell.

Maintaining a Hard Drive Running DOS & Windows

I have put a batch (set of organized command lines), which will DEFRAG and SCANDISK your hard drive. The batch file is compatible with i386/DOS clones, like FreeDOS. Keep in mind that you can only run the batch file in MS-DOS, not from Windows.

If you do not want to see the DOS commands while the batch file is running, start the batch file turning ECHO off.

@echo off

All file are randomly saved on your hard disk. A practical way to manage your disk would be having all parts that form a file together. DEFRAG will organize files fully, defragments files leaving space between them, sorts then by extensions, and skips using extended or upper memory.

defrag/f/u/se/skiphigh c:

SCANDISK repairs problems that your all disks may have automatically without prompting, deletes errors, skips summary, and checks the surface the disk. This line of code might not work with other types of DOS.

scandisk/all/autofix/nosave/nosummary/surface

The batch file 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
temp=c:\temp

If you are running Microsoft Office 6.0 or earlier, you might want to delete all the temporary files. These files start with the tilde character (~).

if exist c:\~*.* del c:\~*.* /f/s/q/a:r/a:h/a:s/a:a
if exist c:\dos\~*.* del c:\dos\~*.* /f/s/q/a:r/a:h/a:s/a:a
if exist c:\windows\~*.* del c:\windows\~*.* /f/s/q/a:r/a:h/a:s/a:a

To delete any temporary files created by other programs, delete by force the contents of the C:\TEMP directory without being prompted to confirm deletion, all sub-directories in C:\TEMP, regardless of their attributes.

if exist c:\temp\*.* 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, deleted.txt). In the example below, the system will first write the date of the batch is run and two blank lines (ECHO.) after the log has been created for cosmetic purposes.

@echo off
echo %date% %time% >> deleted.txt
if exist c:\~*.* del c:\~*.* /f/s/q/a:r/a:h/a:s/a:a >> deleted.txt
if exist c:\dos\~*.* del c:\dos\~*.* /f/s/q/a:r/a:h/a:s/a:a >> deleted.txt
if exist c:\windows\~*.* del c:\windows\~*.* /f/s/q/a:r/a:h/a:s/a:a >> deleted.txt
if exist c:\temp\*.* del c:\temp\*.* /f/s/q/a:r/a:h/a:s/a:a >> deleted.txt
echo. >> deleted.txt
echo. >> deleted.txt

Of course, follow this instructions at your own risk. Although these commands will not normally hurt your system, do not blame me if something goes wrong or if you delete important data by mistake.