Silent Service II: DOSBox deep dive

DarkenedRoom
10 minutes ago
5 min read

A guide to running the 1990 MicroProse pacific submarine sim, Silent Service II in DOSBox Staging as well as a brief look at the history of the sim.

Sequel to the classic 1985 sub sim Silent Service, which was released on practically every 8- and 16-bit platform, SIlent Service II had a more limited development, appearing on the 'big three' platforms, Amiga, Atari ST and DOS.

Versions & patches

Like earlier MicroProse sims, Silent Service II (SS2) used a product number, in this case 457, followed by a version number, running from .01 to .03. Initially distributed on disk, later releases would be a later version (often the final version) released on a single cd or floppy disk.

Both patches can be found in the MicroProse FTP Archive (ftp.microprose.com) hosted on the Internet Archive.

Version 457.01

This was the initial retail release, distributed on DOS with 2 x 3.5" Double Density (DD) 720KB disks.

Version 457.02

The first patch (ssiiv2.zip) was released in September, 1990. It was a bug fix and enhancement release, with additional keyboard commands to control speed and the periscope. It included notes on historical accuracy and running advice. This patch should be installed under DOSBox. This patch was superseded by the 457.03 patch.

Although not required to patch the game, it is still recommended, due to the developer notes that were included with the patch. These notes would not be present in the later .03 patch and are included below:

Version 457.03

The second and final patch (ss2v3.zip) was released in October 1991. It was a bug fix patch but was distributed as a cumulative patch, including the v457.02 patch. This patch should be installed under DOSBox and is a recommended patch for those with earlier versions.

The readme is shown below and the only difference from the .02 readme is the addition of a final warning about saves from earlier versions not working with this version.

Media

SS2 was distributed on a multiple disks or a single cd, but as usual disk/cd images will be used in preference to physical media, to save wear and tear on discs and drive. Physical cd's should be ripped to the iso data only format, as there are no cd audio tracks are on the disc. Digital releases of Silent Service II are available on GOG and Steam.

Game management

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

conf - to store any DOSBox configuration files.
docs - to store any documents, manuals, etc.
cd - to store any cd images ripped from a retail cd.
fdd - to store and disk images ripped from retail disks.
hdd - the DOSBox emulated hard disk folder, to install the game to.

Joystick vs keyboard

Although supporting a joystick, it provides no additional benefit compared to the keyboard. In the Technical Supplement it states many of the development team preferred keyboard rather than joystick control. Due to this, a joystick is not configured in the below DOSBox config. Note: these is no mouse control in SS2.

DOSBox Staging config

This guide assumes the latest version of DOSBox Staging, v0.82.1 (at time of writing).

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

[dosbox]
dos_rate                    = 1000

[cpu]
core                 = simple
cpu_cycles           = 3000
cpu_cycles_protected = auto
cycleup              = 100
cycledown            = 100

[voodoo]
voodoo                    = false

[mouse]
dos_mouse_immediate       = true

[mixer]
reverb     = large
chorus     = normal

[midi]
mididevice      = mt32

[mt32]
model       = mt32_new
romdir      = "D:\Midi\Versioned"

[joystick]
joysticktype                = none

[autoexec]
imgmount a "D:\Games\dos\Silent Service II\fdd\*.ima" -t floppy
# imgmount d "D:\Games\dos\Silent Service II\fdd\ss2.iso" -t cdromm
mount c "D:\Games\dos\Silent Service II\hdd"

c:
# cd mps
# call silent.bat
# 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, a core of simple is optimised for older real mode games. 3000 cycles is the default 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. Cycles up/down is set to a suitably small increment.

Voodoo emulation isn't required and can be disabled.

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

SS2 supports Roland sound, so the MIDI device is set to mt32. The MIDI device is set to mt32_new as SS2 was built for this model, as listed on the VOGONS wiki article, 'List of MT-32-compatible computer games'. This could be omitted to default to a cm32l model which would also be compatible. The rom folder is described in the earlier 'DOSBox midi' article.

Joystick type is set to none as mentioned earlier in 'Joystick vs keyboard'.

There are example imgmount and mount commands to add floppy disk or cd images and the emulated hard disk folder. As there may be multiple multiple floppy disk images the * wildcard is used. The disabled commands can be enabled once installation (and optionally patching) are complete.

Installation

The installer app (install.exe) should be run from the first (or only) floppy disk or cd image, in DOSBox. If a second floppy is requested it should be mounted by swapping disk images (CTRL + F4). Note: the installer version may be a different version than the game.

During the installation the following should be selected:

Option 5 - Install onto Hard Disk, drive C:
Option 1 - MCGA/VGA (256-color)
Option 1 - Roland MT-32 sound

The installation should complete without issue, the installation folder normally being: c:\mps\ss2

Patching

Patching is only required for versions earlier than v457.03. Open the patch zip archive in Win10 and copy the contents to the emulated hard disk folder. Start DOSBox and run the patch installer. The installation should complete without issue.

You may also enable the remaining DOSBox config commands in the [autoexec] section.

Running

To run, go to the c:\mps folder in DOSBox and run silent.bat. The MicroProse start menu.will be shown (see screenshot). This also shows the version number, which is useful to determine if the game needs patching. The following questions will be asked:

Do you have a joystick? No.
Do you want digitized speech? Yes.

Once loading is complete, the copy protection may ask you to identify a ship from the manual.

The patch readme files indicate that ALT + F1 can be used to identify the amount of free memory left during a patrol. However you shouldn't use this command:

As it will open the DOSBox mapper instead.
It isn't needed, as DOSBox will provide more than enough memory required.

Documentation

The following documents are available in a digital/pdf format:

Manual - essential for the copy protection, playing the game and background information.
Technical Supplement - essential control summary and some useful bits of info.
Map of the patrol area - useful for the location of naval bases and water depth.

Good hunting!