688 Attack Sub

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688 Attack Sub
688 Attack Sub cover
Electronic Arts
Release dates
DOS 1989
Modes Multiplayer
688 Attack Sub on HowLongToBeat
688 Attack Sub guide on StrategyWiki
688 Attack Sub on MobyGames
688 Attack Sub on Wikipedia

688 Attack Sub is a multiplayer game.


Source DRM Notes Keys OS
Prompts for answers from manual, code wheel, etc.

Essential improvements[edit]

Packed file is corrupt[edit]

If you receive the error "Packed file is corrupt" when starting the game, make sure you first run LOADFIX. LOADFIX is included with DOS 5.0 or later, and is also included with DOSBox.


The game has options for two-player gaming using either a serial null-modem, or a regular serial modem.

To use the null-modem option a non-standard null-modem cable is required, that is documented in the games manual.
The modem option does not appear to work in every version of the game. Additional clarity is needed, but some versions will disconnect immediately once a connection has been established.
Use DOSBox-X[citation needed]
Select game to play
Select game to play
For Server, select AUTO-ANSWER
For Server, select AUTO-ANSWER
For Client, select ORIGINATE
For Client, select ORIGINATE
Waiting for client to connect
Waiting for client to connect

When run in DOSBox-X, it is possible to use the serial modem emulation to setup a two-player game.

While DOSBox-X also supports null-modem emulation, it is incompatible with the cable type required by the game.
The below emulation option, emulates a modem over a Ethernet connection. It is essential that both machines can reach each other and that there is no firewall blocking communications. For instance the port (12345 in the example below), must not be blocked by the local firewall installed on the computer running the server config.

It is necessary to setup and start one game in "server" mode and the other in "client" mode.

On the "Mission Selection" screen, both players must select the same mission to play, and one player needs to select blue and the other red. Only missions with a lightning symbol next to them are supported for multi-player.

On the "Configuration Panel" screen, both players must ensure that "MODEM ON COM1:" is selected. Then the player with the Server config must select "AUTO-ANSWER" and wait for the client to connect.

The player with the client config must ensure that the "SET TELEPHONE NUMBER" is set to "1", and click "ORIGINATE"

Server Setup - DOSBox-X config

The person that will run in server mode needs to configure his DOSBox-X with the following settings:

title=688 Attack Sub - Server


serial1 = modem listenport:12345 rxdelay:50

mount c .
loadfix /a

Client Setup - DOSBox-X config

The person that will run in client mode needs to configure his DOSBox-X with the following settings:

title=688 Attack Sub - Client


serial1 = modem rxdelay:50
phonebookfile = phonebook.txt

mount c .
loadfix /a

Client Setup - phonebook file

Please create a file named "phonebook.txt" with the following content:

1 localhost:12345

Replace "localhost" in the above phonebook file example with the IP address or hostname of the player running the server config.

Game data[edit]

Configuration file(s) location[edit]

Video and Audio selection
Video and Audio selection

The game does not provide a means to save its config. The game will present the video and audio options each time the game is started.

However, there is a way to start the game directly with your preferred options. For instance if you always want to start the game with VGA (option 4) and Adlib (option 1), you can start the game like such:

688.BAT 41

Save game data location[edit]

System Location


Graphics feature State Notes
Widescreen resolution
4K Ultra HD
Field of view (FOV)
For DOSBox toggle with Alt+ Enter (see the glossary page for other workarounds).
Borderless fullscreen windowed
See the glossary page for potential workarounds.
Anisotropic filtering (AF)
Anti-aliasing (AA)
Vertical sync (Vsync)
60 FPS
Depends on video mode
120+ FPS


Keyboard and mouse State Notes
For DOSBox use the DOSBox Mapper (see the glossary page for other workarounds).
Mouse acceleration
Mouse sensitivity
For DOSBox set in the DOSBox configuration file.
Mouse input in menus
Mouse Y-axis inversion
Controller support
For DOSBox use the DOSBox Mapper (see the glossary page for other workarounds).


Audio feature State Notes
Separate volume controls
Surround sound
Closed captions
Mute on focus lost
For DOSBox change the priority background value in the DOSBox configuration file.
Royalty free audio


Language UI Audio Sub Notes


Multiplayer types

Type Native Players Notes
Local play
LAN play
Online play

Connection types

Type Native Notes
Using serial modem or null-modem
Using serial modem or null-modem

Other information[edit]


Technical specs Supported Notes
DOS video modes Hercules, CGA, Tandy, EGA, MCGA, VGA


No middleware information; you can edit this page to add it.

System requirements[edit]

Minimum Recommended
Operating system (OS) 2.0
Processor (CPU) 8086/8088
System memory (RAM) 384
Hard disk drive (HDD)
Video card (GPU) CGA / Hercules
Needs DOS 5.0 for CD-ROM release