Gravis UltraSound

Lore & Background

The GF1 chip was derived from the Ensoniq OTTO (ES5506) chip, a next-generation version of the synthesizer chip found in the Ensoniq VFX and its successors. The GF1 is purely a sample-based synthesis chip with no built-in codec; sounds must be downloaded to onboard RAM before playback. It does not support hardware compression like IMA ADPCM, so compressed samples must be decompressed prior to loading. The sound quality depends on the selected polyphony level, which is software-programmable, allowing programmers to balance quality and voice count. Advanced effects such as reverberation and chorus are not supported in hardware, though software simulation is possible.

The UltraSound offered MIDI playback by loading instrument patches into adapter RAM, similar to how instruments are stored in ROM on other wavetable cards. The card came with a 5.6 MB set of instrument patch files (*.PAT), most sampled at 16-bit resolution and looped to save space. Support programs used .INI files to describe patch loading for each program change event, allowing Gravis to incorporate a General MIDI-compatible mapping scheme. Windows 95 and 98 drivers used UltraSound.INI to load patches on demand; in DOS, patch loading could be configured separately.

Reader's Guide

The Gravis UltraSound's significance lies in its role as an early affordable wavetable synthesis card for the PC, offering 32-voice polyphony and user-upgradeable sample RAM at a time when most PC sound cards relied on FM synthesis. Its architecture, based on the GF1 chip derived from the Ensoniq OTTO, allowed musicians and game developers to use realistic instrument samples. However, its Sound Blaster emulation was criticized, and native game support was limited, leading Computer Gaming World in 1993 to recommend it primarily for Windows MIDI musicians. The GUS spawned multiple versions and clones, including the UltraSound MAX, Plug & Play, ACE, and OEM variants from companies like Synergy and Primax. The card's legacy continued into the 2010s and 2020s with hobbyist projects such as the PicoGUS (based on the RP2040 microcontroller) and the MK1869 Xtreme, which combined the AMD InterWave chip with an ESS ES1869. These efforts demonstrate the enduring interest in the GUS's unique sample-based synthesis capabilities and its place in retro-computing.

Did You Know?

• The GF1 chip was co-developed by Advanced Gravis and Forte Technologies, creator of the VFX1 Headgear virtual reality helmet.
• The UltraSound Classic was one of the first PC sound cards to feature 16-bit stereo audio.
• The UltraSound ACE was marketed as a competitor to Wave Blaster-compatible cards and was meant to be installed alongside a Sound Blaster Pro/16 card.
• The PicoGUS, an open-source design started in 2022, uses a Raspberry Pi RP2040 microcontroller to emulate the GUS and also supports Tandy 3 Voice, Game Blaster, and Sound Blaster 2.0.

The Six-Degrees-of-Freedom Revolution

Descent II redefined what movement could mean in a first-person shooter by granting the player full six-degrees-of-freedom control over a fighter spaceship in zero gravity. Rather than being locked to a flat plane like conventional shooters of the era, the pilot can translate and rotate freely along three axes—pitch, yaw, and roll—giving the experience a genuine sense of three-dimensional flight. Parallax Software, the developer behind the title, designed the control scheme to feel like piloting a craft through the cavernous interiors of extrasolar mines. The game shipped in 1996 for MS-DOS under Interplay Productions' publishing banner and supported an unusually broad range of input hardware beyond a standard keyboard. Players could use the Gravis Gamepad or various joysticks, several of which offered force feedback, making Descent II one of the earliest PC titles to integrate that technology. Stereoscopic graphics and virtual reality setups were also officially supported, pushing the game toward immersive experiences well ahead of its time.

The Mine Campaign Structure

The single-player campaign unfolds across six themed star systems, each containing four levels the player must clear in sequence. The core objective in every level is straightforward: locate the mine's reactor, destroy it, and race through an exit door before the facility's self-destruction countdown reaches zero. The exit door only opens once the reactor is destroyed and the meltdown timer begins, creating a tense window for escape. Every fourth level swaps the reactor for a boss robot, adding a combat challenge to the standard demolition task. Navigation within the mines is deliberately complex. Rooms are linked by doors that can be shot open or bumped into, while colored doors in blue, yellow, or red demand matching keys. To combat the disorientation of zero-gravity corridors, players can deploy flares, activate a headlight, consult a wireframe automap charting all explored areas, or drop markers that appear on that map. A commandable Guide-Bot, freed along the way, can be ordered to lead the player toward a specific objective or power-up. Human hostages scattered through levels award bonus points if rescued before the level ends, and control panels hidden in walls, when shot, trigger events like opening sealed doors, removing barriers, or deactivating force fields.

Arsenal & Survival Mechanics

The weapon system in Descent II splits into primary and secondary categories. Primary options include a range of pulse lasers and plasma bolts that drain the ship's energy banks, alongside two rotary cannons that fire explosive shells from a finite magazine. Secondary weapons comprise various missile types and proximity mines that drop behind the ship to impede pursuing enemies. Ten entirely new weapons were introduced over the original, including the Phoenix cannon whose energy orbs ricochet off walls, the Omega cannon delivering electrostatic discharge, the Flash Missile that blinds both robots and players for two seconds while producing a disorienting ringing tone, and the Guided Missile, which the player can steer remotely after launch. Beyond weaponry, equipment items grant special capabilities. A converter redirects any energy above 100 units into shield capacity, while an afterburner temporarily doubles forward speed. The ship's shield, capped at 200 units, absorbs damage from enemy fire and force-field collisions; once fully depleted, any further hit destroys the vessel, costs a life, kills any hostages aboard, and scatters most weapons at the crash site. A respawning player re-enters at the level entrance with only minimal armaments, making retrieval of lost gear a significant challenge. New to the sequel is the ability to deliberately drop weapons, allowing players to stockpile surplus firepower in safe locations for later recovery.

From Expansion to Standalone & Critical Reception

Descent II began life as a planned compact-disc expansion of the original Descent, leveraging the CD's larger storage capacity to add content. The project ultimately evolved into a fully standalone product, built on an upgraded version of its predecessor's graphics engine. Released in 1996 by Interplay Productions for MS-DOS, the game earned very positive reviews from video game critics. The multiplayer mode drew particular praise, as did the Guide-Bot, a scouting robot that players could free and command to navigate toward objectives or power-ups. The title also appeared on PlayStation under the name Descent Maximum, though that port received a more divided critical response. Reviewers frequently disagreed with one another over the console version's frame rate, with some finding it acceptable and others considering it a significant drawback. The original Descent, developed by Parallax Software, had established the series' identity, and Descent II cemented its reputation as a genre-defining experience. A third installment, Descent 3, followed in 1999, continuing the franchise's legacy in the first-person shooter space.