Running DOS under linux

1) Introduction

Even though MSDOS is a legacy operting system,  there  are a number of applications written exclusively for it. Also DOS has very low resource requirments and hence can run on  ancient hardware. This document describes how to set up  DOS on a linux machine using dos emulator.

2) DOS versions
  Major Dos versios currenly available are. MSDOS 6.2 DRDOS 7.03 and freedos.
 Dos emulator can run any of the above versions 

3) Software  required

  The following programs are required to run DOS
 
  ftp://ftp.dosemu.org/pub/dosemu/dosemu-1.0.2-bin.tgz
  ftp://ftp.dosemu.org/pub/dosemu/dosemu-freedos-bin.tgz
  
  dosemu-1.0.2-bin.tgz is the binary of latest dos emulator
  dosemu-freedos-bin.tgz is the image for freedos
  
 If you want to run MS DOS you need an MSDOS boot disk with all necessary programs

4) Installation
  Create a new user called dos. login as dos
  Download  the above files
  uncompress and untar
  $ gunzip dosemu-1.0.2-bin.tgz
  $gunzip dosemu-freedos-bin.tgz
  $tar -xvf dosemu-1.0.2-bin.tar
  $ tar -xvf dosemu-freedos-bin.tar
  
  All the files will be untarred to a directory named dosemu

  $cd dosemu
  $./dosemu
   Your enulator will start and a copy of freedos will be booted
 Play around it.
 To come back to $ prompt type EXITEMU
 
5) Booting msdos
  Make a directory to hold msdos files
  
  $ mkdir ~/dosemu/msdos
  
  Mount your msdos boot floppy and copy all files to ~/dosemu/msdos
  copy boot sector of the floppy 
   ( Alternately you can use  mtools package which provide dropin replacemnet
   for dos commands. eg mdir a:  , mcopy a:*.*)
   
  $ cd ~/dosemu/msdos
  $ dd  dd if=/dev/fd0 of=boot.blk bs=512 count=1
  
  Edit ~/dosemu/conf/dosemu.conf
  Look for a line  
  
   $_hdimage = "freedos"
   change it to 
   $_hdimage = "msdos"
   
 Save the file
 Copy  the contents of ~/dosemu/freedos/dosemu to msdos directory
 $cp ~/dosemu/freedos/dosemu  ~/dosemu/msdos
 
 Now change directory to ~/dosemu/
 start MsDos with
 $ ./dosemu
 If everything is ok your MSDOS will startup
 
 Exit dos by typing exitemu

5) Adding additinal drives

Adding additinal drives and software is very easy
 
 Create a directory user in ~/dosemu
 $mkdir ~/dosemu/users
 edit ~/dosemu/conf/dosemu.conf
 Change the line 
 $_hdimage = "msdos"
 to 
 $_hdimage = "msdos users"
 Start msdos
 Now user directory will be your D:
 You can add any number of drives this way.
 The configuration file offers a number of options which you can try
 It is possible to access netware servers from within dosemulator

6) Fooling people 
 The  dos setup done this way may be combined with LTSP so that you can manage all your dos programs and users centrally. The problem is that anybody can log into dos accout and change the settings. In order to prevent it do the following
 
 Delete the passwoed of dos account
 
 $ passwd -d
 
 Edit .bash_profile
 Add the following lines towards the end
 
 /home/dos/dosemu/dosemu
 logout
 Save the file
 Logout and then login as dos
 Dos will  automaticaly startup
 
 ( A clever user can make a work around)
 
7) Conclusion
   The dosemu  is a very good dos emulator which can be effectivly used. If you are using LTSP along with dosemu you will have very good control over your software as well as network.
 
8) References
  http://www.dosemu.org
 

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