GAMEBOOMERS DOSBox FAQ

By Steve Metzler, aka MetzO'Magic (Last updated: 29th November, 2007)

Forward
Since the advent of DOSBox 0.70, it's become a lot easier to configure. So the DOSBox FAQ needed a bit of an overhaul as a consequence, due to some of the advice given being either unnecessary, or even outright misleading.

Also, Vista has come along in the meantime. Most of what is written here should apply to Vista in the same way as it does to XP. Just be careful to install DOSBox, as well as any DOS games you want to run, in a folder that's under control of your normal user account where you have privileges (NOT an Administrator account). Otherwise, you won't be able to edit the dosbox.conf file, or in fact do much of anything that's useful :-\

Q. About DOSBox, VOGONS, and my e-mail address: please read me first!
A. DOSBox is the combined effort and lifeblood of a team of people dedicated to preserving the legacy of the gaming platform that was DOS on modern operating systems. I can take no credit whatsoever for any part of its creation. However, I am an enthusiastic user of DOSBox, and you will find me seizing every opportunity to evangelise its use in the gaming community.

The VOGONS (Very Old Games On New Systems) forum is the public face of the DOSBox team. They are very busy people, and before posting any questions there you should ensure that:

  1. You have read this FAQ first.
  2. If you didn't find the answers to your questions here, you then tried to find them in the 'README.txt' file that is distributed with DOSBox.
  3. Still no joy? Then e-mail me at:

    stevemetzler at utvinternet dot ie

    (remove all spaces, change the 'at' to '@', and the 'dot' to '.')

  4. As a last resort, you can post a question to the VOGONS DOSBox General forum. BUT, you must read their posting guidelines first and adhere to them!

Q. What is DOSBox?
A. DOSBox emulates a copy of good old DOS running on a 286 or 386 PC. An emulator is, in simple terms, a programme that runs on your computer that enables you to run other programmes that were developed for a different computer or operating system. DOSBox was specifically designed to run old games that will no longer run on modern operating systems. In our case, that usually means: Windows XP/Vista and MacOS X.

Q. Where did DOSBox come from?
A. Another planet. Actually, I eventually discovered from one of the DOSBox developers who read this FAQ... that it was mainly instigated by the release of Windows 2000, which would no longer run DOS games. But it also benefits the non-Windows camp, because it runs on: Windows, Linux, and MacOS X, to name but a few. It is an open source project, and that means it's free for all of us to use... subject to certain restrictions, like that you don't try to sell it to your unsuspecting neighbour.

Q. Surely a modern computer can run some manky old DOS programmes!
A. If only it were that simple. But Microsoft have been trying to distance themselves from DOS for years. Among its most frustrating limitations: DOS can only do one thing at a time, and it is liable to crash if any programme does something... naughty. The break from DOS started with Windows NT (New Technology). NT got rid of the DOS limitations, but at the expense of backwards compatibility. Fundamentally, it no longer allowed programmes to directly access the hardware (which they were primarily doing for performance reasons), so old programmes that did this would no longer work in NT. But the system was more robust as a result. It was a trade-off. Windows XP is from the same stable as Windows NT, and thus you have the same problems trying to run those old 'misbehaving' programmes.

Q. How does DOSBox work?
A. Easy one :-) It uses a thing called the Simple DirectMedia Layer (SDL) to 'abstract' itself from the actual operating system and hardware. Then DOSBox puts another layer on top of that that makes it appear as if as if the hardware that was typically in an old 386 PC is present, most notably: sound. But all this wonderfulness comes at a cost: it is relying on the fact that machines nowadays are many, many times faster than they were, say, 10 years ago...

Q. Could we have that again in plain English, please?
A. What DOSBox does is emulate (he's boring me now with this word, you say) a certain amount of 286/386 processor instructions per millisecond. Because this is done in software, you need a much more powerful machine to get the same kind of performance you got with that old 386 PC. The requirements vary from game to game. Attempting to keep up with a game like Realms of the Haunting that even stretched the limits of a high end 486 machine takes a lot more processing power than something like Hitchhiker's Guide to the Galaxy, a static text adventure with no sound. But this 'instructions per millisecond' concept has a hidden benefit: you can precisely control how fast a game runs, thus obviating the need for special 'slow down' programmes like Mo'Slo...

Q. So, what are the system requirements for DOSBox then?
A. As alluded to above, it depends. To get a decent frame rate out of Tex Murphy: Under a Killing Moon, for example, I found that you need at least a 2GHZ processor. Older DOS games, like most 2D adventures, can get away with much less. A 500MHZ PIII might do. In the Windows world, DOSBox will run on: 95/98, ME, NT/2000/XP/Vista. But it is unlikely you will be running something like Win 98 on a machine that is powerful enough to emulate(!) even a slow 386, so beware. Having said that though... if you happen to be running Win 98 on a relatively fast machine, then it is actually easier to get old games running on DOSBox than it is to muck around with
config.sys and autoexec.bat in an effort to get enough free memory, etc.

Q. OK, you've piqued my interest. How do I get this thing?
A. Go to the DOSBox project site and download the latest version for your operating system. At the time of writing, the version was: 0.72. It practically installs itself. In the case of Windows, just double-click on the .exe file you downloaded.

Q. Downloaded and installed it, what next?
A. Well... there are various graphical user interfaces (GUIs) for DOSBox that are supposed to make it easier for the average person on the street to use, but I'm one of those Luddites (relatively speaking, of course) who prefers to hand-edit configuration files. And it's really quite easy as there are only a few things in the
dosbox.conf file you usually need to mess with to get any game running... you can probably see where this is all leading. Yes, I'm attempting to create an army of geeks to keep me in good company.

Q. So where is this 'dosbox.conf' file and how do I edit it?
A. If you installed DOSBox to the default folder, which would be something like:

C:\Program Files\DOSBox-0.72

Then just browse to there using Windows Explorer and open dosbox.conf in Notepad. You only need to change a few things:

  1. Full screen mode by default. This is easily accomplished via:
    fullscreen=true

  2. How many 286/386 processor cycles DOSBox will emulate (I grow weary, really I do) per millisecond. With earlier versions of DOSBox, you had to guess this setting according to the game's requirements and your processor speed. But the best new feature of DOSBox (since 0.70) is that it can automatically figure out the correct value :-) To accomplish this, it's best to set:
    cycles=max

    And you'll never have to touch this setting again. What this also means is that: YOU NO LONGER NEED A DIFFERENT VERSION OF dosbox.conf FOR EVERY GAME. Fantastic!

  3. Especially if you are playing a game that runs in the old 320 x 200 mode, you'll want to change the following settings from their defaults to correct the aspect ratio (screen will appear squashed otherwise) and to anti-alias (smooth out) the graphics on today's larger monitors:
    aspect=true
    scaler=supereagle

  4. There is a section at the very bottom of dosbox.conf that is used to set up your CD-ROM and hard drives. You should just copy and paste the following lines into dosbox.conf, right over the [autoexec] section that is already there:

    [autoexec]
    # Lines in this section will be run at startup.
    mount D D:\ -t cdrom -usecd 0 -ioctl
    mount C C:\
    C:

    If your CD-ROM drive is not D:, then just substitute E's or whatever for the D's above.

Q. How do I start up DOSBox?
A. Just open a Command Prompt via:

Start > All Programs > Accessories > Command Prompt

Then go to the folder where you installed DOSBox to, like:

cd \program files\dosbox-0.72

And finally, you enter:

dosbox

It's that simple! After DOSBox starts up, you just navigate to the folder where your game is installed, and run it with whatever DOS commands are necessary.

Q. My DOS game won't install in Windows. What do I do?
A. Start up DOSBox, and then install the game that way. Quite often an old game will do the sound configuration at install time, so you need to be running the game installation in DOSBox for this to work anyway.

Q. What sound settings should I configure for my DOS game?
A. I found that you get the best trade-off between quality and performance if you set the game up as if it's using a SoundBlaster Pro. If the game doesn't support a SoundBlaster Pro, then go for the basic SoundBlaster. Alternatively, you can let the game in question auto-detect the sound hardware. But of course, this will only work if you are running DOSBox at the time you install the game.

One reader has reported that you can get better digital sound quality using the Gravis UltraSound emulation (uh...) if the game in question supports it. I have tried this on Under a Killing Moon and the sound is indeed sharper. You can then use General MIDI for the music.

Q. How do I configure a floppy drive?
A. In the [autoexec] section of
dosbox.conf, just add the following line (right after the line that begins with "# Lines in this section..." ):

mount A A:\ -t floppy

Q. How do I mount a CD-ROM drive in Windows 95/98?
A. Whereas the following mount command works fine in Windows NT/2000/XP/Vista:

mount D D:\ -t cdrom -usecd 0 -ioctl

That won't work in Windows 95/98. You need to use this variant instead:

mount D D:\ -t cdrom -usecd 0 -aspi

Q. What if the sound doesn't work?
A. The section in
dosbox.conf that relates to the setting up of your sound card looks like this:

[sblaster]
# type -- Type of sblaster to emulate:none,sb1,sb2,sbpro1,sbpro2,sb16.
# base,irq,dma,hdma -- The IO/IRQ/DMA/High DMA address of the SoundBlaster.
# mixer -- Allow the SoundBlaster mixer to modify the dosbox mixer.
# oplmode -- Type of OPL emulation: auto,cms,opl2,dualopl2,opl3.
#            On auto the mode is determined by sblaster type.
# oplrate -- Sample rate of OPL music emulation.

type=sb16
base=220
irq=7
dma=1
hdma=5
mixer=true
oplmode=auto
oplrate=22050

Usually, the only thing that will differ from game to game is the IRQ (Interrupt Request line). For instance, most Sierra 'Quest' games expect the IRQ to be 5, instead of the default which is 7. So, for these games you would set:

irq=5

If in doubt, either the sound set-up for the game, or the manual, should give you some clue as to what the possibilities/expectations for the IRQ are.

Another thing that could happen regarding sound is that your PC will normally be utilising full hardware sound acceleration - something that did not even remotely exist back in the good old DOS days. If you suspect this might be a problem, try the following:

Start > Run > dxdiag.exe

Then go to the Sound tab, and knock the 'Hardware Sound Acceleration Level' down a notch or two. Start up DOSBox again, and see if that gets you some sound. (note: this approach will not work in Vista, which believe it or not does not support hardware sound acceleration!)

Q. What if the sound is stuttering or the video is going too slow?
A. The sound is rarely going to be crystal clear because we are not using real sound hardware, remember? But if there are too many 'clicks', or the sound is cutting out, or the video is going too slow in a 3D game and you just keep spinning around when you try to move... then you are probably trying to emulate (sigh) more cycles per millisecond than your machine is capable of handling.

With versions of DOSBox prior to 0.70, you could try fiddling around with the cycles= and frameskip= parameters in dosbox.conf in an attempt to find the best settings for this particular game/machine configuration. But with DOSBox 0.70 and a cycles=max setting, I'm afraid that if you're having problems of this nature then your machine is just not up to running that particular game. Sorry.

Q. The video is looking a bit strange. Anything I can do?
A. This problem only happens on certain machines and most likely stems from trying to run with full hardware acceleration. Go to your Windows desktop, right-click on 'Properties' to bring up Display Properties, then choose:

Settings > Advanced > Troubleshoot

Crank the 'Hardware acceleration' setting down a notch or two, then try starting up DOSBox again.

copyright 2007 GameBoomers Group