Chucking it in DOSBox: Chuck Yeager's Air Combat

DarkenedRoom
May 2
10 min read

A guide to running the standard DOS and Gravis UltraSound (GUS) optimized versions of the 1991 Electronic Arts/Brent Iverson sim, 'Chuck Yeager's Air Combat' in DOSBox Staging.

In a list of classic sims that got large numbers of people into the flight sim genre, near the top, would be Chuck Yeager's Air Combat (CYAC). Created by sim designer Brent Iverson, who had already completed LHX: Attack Chopper, in 1990, and would go on to created the Jane's Fighter's series culminating in Jane's Fighters: Anthology and assisted by the man himself, Chuck Yeager, whose flight experience, testing and advice helped make CYAC the universally well regarded and classic sim it became.

You can read more about it on MobyGames.

Versions

There are three DOS versions of interest (not counting the Mac version), two 'standard' DOS versions and a GUS optimised version.

The initial commercial release was v1.0 in 1991. Released on 4 x 5.25" Double Density (DD) 360KB floppy disks or 2 x 3.5" DD 720KB floppy disks.

A later commercial re-release increased the version to v1.1. Released on 2 x 3.5 DD floppy disks. Later re-releases, budget re-releases and compilation releases would include CD-ROM media. Version 1.1 made changes to joystick handling which makes it more DOSBox compatible. A list of other changes are listed in a readme file from a later release, and included below:

A Gravis UltraSound (GUS) sound card optimised version, 1993, was never commercially released as a separate product, but came included with the GUS sound card. It was distributed on 4 x 3.5" DD 720KB floppy disks. This version still uses the v1.1 number within the flight menu, but uses GUS enhanced music and audio and lists the version as 'Advanced Gravis Ultrasound Version 1.0G' within the credits!

The recommended version is v1.1/v1.0G and depending on the desired gameplay experience, either the standard or GUS version should be chosen. For those new to CYAC the GUS version is recommended.

Media

As usual I recommend ripping any floppy disk versions to an img or ima floppy image file that can be read by DOSBox.

Physical cds can be ripped to a data only iso image as there is no cd audio/music on the disk (at least none used by CYAC if it's in a compilation release).

The media, especially physical floppy disk media may be over 30 years old so saving wear and tear on disks (and drives) is important, so I recommend the use of floppy/cd images.

Game management

I recommend using my DOSBox game management strategy, the recommended game management folders are:

conf - to store any DOSBox or HOTAS configuration files.
docs - to store any documents, manuals, etc.
cd - to store any cd images ripped from a retail cd (if using a cd image).
fdd - to store any cd images ripped from floppy disks (if using floppy images).
hdd - the DOSBox emulated hard disk folder, to install the game to.

If you want to try both standard and GUS versions then add:

hdd-gus - another DOSBox emulated hard disk folder, to install the GUS version to.

HOTAS config

Only the joystick is supported in the retail game, but throttle support can be added with a utility (see 'Patches and utilities').

Configuring axes may not be required if your HOTAS has 4 axes or less. When using devices totaling more than 4 axes, a virtual controller can be used, limited to 4 axes.

As I have rudder pedals I tend to configure all the devices in my virtual controller, even if they aren't used (like the rudder pedals in this case). This prevents DOSBox from trying to assign the rudder pedals as the joystick controller.

The physical axes to Windows axes were configured as follows:

Physical axis	Windows axis
Joystick x-axis	DX_X_AXIS
Joystick y-axis	DX_Y_AXIS
Throttle	DX_Z_AXIS
Rudder	DX_XROT_AXIS

DOSBox Staging config

This guide assumes the latest version of DOSBox Staging is used, v0.82.1 at time of writing. This sections covers settings applicable to both the standard and GUS versions, which differ from the default DOSBox Staging config.

[sdl]
host_rate           = vrr
vsync               = off
presentation_mode   = vfr

[dosbox]
dos_rate                    = 1000

[cpu]
cpu_cycles           = 10000
cpu_cycles_protected = auto
cycleup              = 100
cycledown            = 100

[voodoo]
voodoo                    = false

[mouse]
dos_mouse_immediate       = true

[mixer]
reverb     = medium
chorus     = normal

[joystick]
joysticktype                = 4axis
timed                       = false
swap34                      = true
deadzone                    = 0

[autoexec]
# Example image mount commands
# imgmount a "D:\Games\Dos\Chuck Yeager Air Combat\fdd\*.img" -t floppy
# imgmount d "D:\Games\Dos\Chuck Yeager Air Combat\cd\ChuckYeagersAirCombat.iso" -t cdrom

# Example hard disk mount commands
mount c "D:\Games\Dos\Chuck Yeager Air Combat\hdd"
# mount c "D:\Games\Dos\Chuck Yeager Air Combat\hdd-gus"

c:

# CYAC joystick TSR utility
# cd tsr
# cyac_2ja
# cd ..

# Running CYAC, note the installation folder may be different
# cd combat
# yeager

# Close DOSBox after quitting the game
# exit

The [sdl], [dosbox] and [mouse] settings are suitable for high frame rate gaming as described in this article by Omniclyde. These settings aren't strictly required and can be omitted to use the default settings.

In [cpu] settings, 10000 seems like a good setting for my machine but you may wish to change this to personal preference. The cpu_cycles_protected setting will use the same cycle count as cpu_cycles when set to auto.

Voodoo emulation isn't required and can be disabled.

The [mixer] settings can be changed to enhance sound and music to personal preference.

The [joystick] settings are appropriate for my HOTAS setup so you may need to alter these. The CYAC joystick utility failed with timed set to true and false is generally preferable. Deadzone is set to a personal preference.

The autoexec section contains disabled (commented out) examples, these should be enabled or tweaked depending on what images and/or utilities were used, it contains:

Example imgmount commands for floppy disk and cd images.
A second emulated hard disk folder for the GUS version (if required).
Example commands for calling the CYAC joystick TSR.
Example commands for running the game.
Closing DOSBox after quitting.

You should configure the game before running it from the DOSBox config file.

Standard version

This sections covers sound and music settings applicable to the standard version, which differ from the default DOSBox Staging config.

[speaker]
lpt_dac             = covox

The standard version will use Soundblaster for music and most sound, however the default settings do not have to change.

CYAC supports the Covox Speech Thingy which provides enhanced speech. The lpt_dac setting enables Covox emulation.

GUS version

This sections covers sound and music settings applicable to the GUS version, which differ from the default DOSBox Staging config.

[sblaster]
sbtype              = none

[gus]
gus        = true

[speaker]
lpt_dac             = none

The GUS version will use GUS for music and sound so Soundblaster emulation should be disabled.

In the 'gus' section, GUS emulation should be enabled, the remaining settings can remain at the default values.

In the speaker section, the lpt_dac setting defaults to none (so not strictly required), however if you have copied the standard config, remember to disable this or remove it to revert to the default value.

GUS driver installation

This next section is only required if you wish to run the GUS version. The GUS version requires GUS drivers and VOGONS forum member K.A.R.R. has produced a GUS driver package comprising of:

Pre-installed Gravis UltraSound driver 4.11 (latest official version).
Pre-installed Gravis UltraSound driver 4.11 with Pro Patches Lite 1.61.
Pre-installed Gravis UltraSound driver 4.11 with Pro Patches Lite 1.61 and anti-loop fix.
The files required to create the above installations.

The VOGONS forum post contains a setup guide for each, and Rincewind42 has archived it at the Internet Archive along with the setup guide. So a huge thank you to both for making GUS setup extremely easy!

Since DOBox Staging is used, there is a choice of:

Pre-installed Gravis UltraSound driver 4.11 (latest official version).
Pre-installed Gravis UltraSound driver 4.11 with Pro Patches Lite 1.61 and anti-loop fix.

DOSBox Staging requires the addition of the anti-loop fix to the Pro Patches Lite 1.61. Either is recommended and I opted for the 'Pre-installed Gravis UltraSound driver 4.11 with Pro Patches Lite 1.61 and anti-loop fix' (ULTRASNDPPL161FIX.zip).

All that was required was to unzip the ULTRASND folder into the emulated hard disk folder using Win10. The next time I started DOSBox the ULTRASND folder was available.

Installation

The floppy images usually have an installer app called install.bat or install.exe, depending on a particular release. These should be run with DOSBox. As there are multiple disk images you will have to use DOSBox to swap between images (CTRL+F4) to complete the install. The floppy install should complete without issue.

The cd/cd images may have a similarly named installer app or you may have to look for a suitable batch (.bat) or executable (.exe), e.g. runme.bat, dependant on the release. Once found run in DOSBox, it should complete without issue.

The installer will normally copy files to C:\COMBAT or C:\EA\COMBAT, again dependant on release. Ensure the [autoexec] section of the DOSBox config reflects this.

Patches & utilities

At present I haven't been able to find a v1.1 patch which makes selecting the correct version even more important. If anyone has the patch or knows where it is or can even confirm it exists, please get in touch.

CYAC joystick TSR

There is a CYAC joystick TSR utility (cyac2j.zip) created by Heinz-Bernd Eggenstein (a familiar name in Tornado patches and utilities) that can be used to enable the throttle in game. Thanks to VOGONS forum rfnagel and some deep digging through his archives, it can be found in his post and to Heinz-Bernd for giving us a throttle in CYAC!

The zip package comprises of:

cyac_2ja.com - for analogue throttles.
cyac_2jd.com - for digital throttles (or second joystick).
cyac_2j.doc - instructions.
stick.exe - a stick and throttle test utility.

The screenshot shows the cyac_2ja.com being run. The utility is also compatible with the GUS version.

A suggested location to extract to is a TSR folder under the emulated hard disk folder. Running the utility can be automated through the DOSBox config [autoexec] section.

Configuration

CYAC is configured through command line options. Once the game has started those options are written to a configuration file and used if the game is run without command line options. This means the command line options are only required the first time a the game is run but can be set as many times as needed by specifying options. The order of options does not matter as long as they are separated by a space.

The standard version using the earlier DOSBox, config is run with:

C:\COMBAT>yeager VGA FASTCARD JOYSTICK HIGH BLASTER COVOX1 LARGE

The GUS version using the earlier DOSBox config, is run with:

C:\COMBAT>yeager VGA FASTCARD JOYSTICK HIGH LARGE

Command line options

The command line options are included for reference:

CGA	Loads game with CGA graphics.
EGA	Loads game with EGA graphics.
MCGA	Loads game with MCGA graphics (Same graphics as VGA, but slower. Maintains compatibility with PS/2 25 and 30).
TGA	Loads game with Tandy graphics.
VGA	Loads game with VGA graphics.
SLOWCARD	When you are MCGA or VGA mode, if the game freezes on startup, or if you get sound but the wrong colors or no colors at all, try this parameter. It slows down the interface between the computer and the video card.
FASTCARD	Deactivates Slowcard.
JOYSTICK	Loads game with joystick flight control.
KEYBOARD	Loads game with keyboard flight control.
MOUSE1	Loads game with mouse flight control.
MOUSE2	Loads game with high-resolution mouse flight control.
LOW	Loads game in low graphics detail mode (less detail speeds up game play).
MEDIUM	Loads game in medium graphics detail mode (less detail speeds up game play).
HIGH	Loads game in high graphics detail mode.
NOSOUND	Loads game with sound turned off.
NOSPEECH	Loads game with digitized speech turned off. It also reduces the amount of disk swapping necessary when playing on four 360k floppies.
PC	Loads game with PC internal speaker sounds.
ADLIB	Loads game with AdLib sound card sounds.
BLASTER	Loads game with Sound Blaster sound card sounds.
TANDY	Loads game with Tandy 1000 sound.
TANDYDAC	Loads game in Tandy 1000 models equipped with DAC (such as the Tandy 1000 TL), which results in clearer digitized speech.
COVOX1	Loads game with loud speech driver for the Covox Speech Thing on parallel port 1. Note: there is no auto-detect for Covox, so this parameter is required if you want to use Covox.
COVOX2	Loads game with loud speech driver for the Covox Speech Thing on parallel port 2. Note: there is no auto-detect for Covox, so this parameter is required if you want to use your Covox.
CMS	Loads sound driver for CMS music board. Note: there is no speech driver for CMS, so digitized speech will play through the PC’s internal speaker. Also, there is no auto-detect for CMS, so this parameter is required if you want to use your CMS Board.
SMALL	Use this if you have a computer with less than 640K of memory. It deletes complex versions of some shapes to speed up the simulation.
LARGE	Deactivates Small.
ALL	If you want to be able to play all missions without having to win each one, type this parameter to make all missions available immediately. This is a default parameter.
CAMPAIGN	Starts new campaign. In order to advance in Campaign Mode, you will need to land safely at your home base after successfully completing each mission. (See p.25 in manual)

If you quit the game in the middle of a Campaign, and you want to return to where you left off, be sure not to select the Campaign parameter the next time you start up the game, as that will put you at the beginning of a new campaign.

Running

Once command line options are set, either version can be run with:

C:\COMBAT>yeager

This can be added to the DOSBox config in the [autoexec] section.

In-game configuration

The final step is to check the in-game configuration. The easiest way to do this is start a test flight and access the in-flight menu to check all the options are set correctly. Control and graphics options should be checked. Options set here will also be written to the configuration file used by command line options.

Documents

There are digital copies of both the manual and reference card, obtaining both is recommended. The reference card lists the command line options and the manual is required to pass the copy protection check, being based on the stats of various aircraft encountered in the game.

Some versions of CYAC may disable the copy protection but it is still enabled on the GUS version.

'It's a great day for flying!' - Chuck Yeager