Gravis UltraSound

The first UltraSound was released in early October 1992, along with the Gravis PC GamePad. The Ultrasound was one of the first PC soundcards to feature 16-bit, 44.1 kHz stereo. The final revision (v3.74) of the GUS Classic features 256 kB of onboard RAM (upgradeable to 1024 kB through DIP sockets), hardware analog mixer, and support for 16-bit recording through a separate daughterboard based on the Crystal Semiconductor CS4231 audio codec.

Computer Gaming World in 1993 criticized the UltraSound's Sound Blaster emulation and lack of native support in games, stating that "it is hard to recommend this card to anyone other than a Windows MIDI musician".[1]

Gravis UltraSound MAX

Released in 1994, UltraSound Max is a version of the GUS with a CS4231 codec on board, 512 kB of onboard RAM (upgradeable to 1024 kB with a single SOJ chip), and Panasonic/Sony/Mitsumi CD-ROM interface slots. CS4231 provides support for Windows Sound System specs, although the IO port range doesn't match the WSS hardware, and can be used for SoundBlaster emulation. The software CD includes a demo that featured "3D holographic sound" through the use of software HRTF filters.

Gravis UltraSound PnP Pro

Released in 1995, the Ultrasound Plug & Play was a new card based on AMD InterWave technology with a completely different sound set. Supposedly Synergy acted as the ODM-producer for it (as evidenced by their logo on the rear side of the card, although early and now very rare GUS PnP cards did not have the Synergy logo). The card features 1 MB of sound ROM, no onboard RAM (although it can be expanded to 8 MB with two 30-pin SIMMs), and an ATAPI CD-ROM interface. A 'Pro' version adds 512 kB of on-board RAM required for compatibility with the GUS Classic. In 2014, a RAM adapter for the 72-pin SIMM was produced by retro-computer enthusiasts that made it possible to install 16 MB of RAM on the 'Pro' version without any modifications to the card.

Released in 1995, this budget version of UltraSound Classic has 512 kB of RAM (upgradable to 1024 kB, just as is the MAX), and has no game port or recording ability. Marketed as a competitor to Wave Blaster-compatible cards, it is supposed to be installed alongside a SoundBlaster Pro/16 card as a sample-based synthesis (marketed as 'wavetable synthesis') upgrade. A prototype of this card was named "Sound Buddy".

Gravis UltraSound ACE

An OEM version of UltraSound Classic produced by Synergy, with 512 – 1024 kB of RAM. It features AT-BUS CD-ROM interfaces following Sony, Mitsumi and MKE/Panasonic standards. This is the only Gravis sound card with a green circuit board. It is similar to a few card clones, including the Primax SoundStorm Wave (model Sound M-16B) and the AltraSound.

Released in 1996, the UltraSound Extreme is a 3rd party OEM system combining the UltraSound Classic with an ESS AudioDrive ES1688 sound chip for Sound Blaster Pro and AdLib emulation. It was produced by Synergy as was the ViperMAX. It has 1 MB RAM by default, but cannot be upgraded any further.

Gravis UltraSound Extreme

All clones use the original Gravis GF1 or the AMD InterWave soundchip.

• Primax SoundStorm Wave (GF1) - there are two variants of cards from the well known scanner and mouse producer. Re-labeled Altrasound as Sound M-16B and different Sound M-16C with 4x CD-ROM Interfaces.
• D&B UltraWave (GF1) - this card has 512 kB onboard RAM by default, upgradeable to 1024 kB RAM using a 512 kB SOJ-40 DRAM chip. Has a DIP socket for a 16 kB boot ROM (optional) and an IDE interface (secondary).
• Synergy ViperMAX (GF1) - same card later repacked as UltraSound Extreme, but with only 512 kB RAM on board.
• Expertcolor MED3201 (InterWave LC) - probably the only card with cut-down variant of GFA1 chip - AM78C200 InterWave LC. First series was with standard Am78C201KC.
• Compaq Ultra-Sound 32 (InterWave) - one of the last InterWave cards was designed for Compaq Presario desktops. Newer "C" revision of InterWave - AM78C201AKC and TEA6330T fader. Produced by STB Systems.
• STB Systems Soundrage 32 (InterWave) - standard InterWave card missing SIMM slots and IDE interface. There was "Pro" variant with 512 kB RAM. AM78C201KC chip.
• Core Dynamics DYNASonix 3D/PRO (InterWave) - features additional DSP chip that offered a graphic equalizer and additional sound FX presets.
• Philips PCA761AW (InterWave) - card design closely resembles the "AMD InterWave OEM Design" prototype. Has a footprint for 512kb RAM, often left unpopulated. AM78C201KC chip.
• Reveal WAVExtreme 32 (InterWave) - AM78C201KC based design. Comes without RAM and has no sockets/footprints to add any.
• As of February 2015 there have been efforts by hobbyists to produce a new InterWave based UltraSound compatible soundcard named ARGUS.

The UltraSound offers MIDI playback by loading instrument patches into adapter RAM located on the card, not unlike how instruments are stored in ROM on other sample-based cards (marketed as "wavetable" cards). The card comes with a 5.6 MB set of instrument patch (*.PAT) files; most patches are sampled at 16-bit resolution and looped to save space. The patch files can be continuously tweaked and updated in each software release.

The card's various support programs use .INI files to describe what patches should be loaded for each program change event. This architecture allowed Gravis to incorporate a General MIDI-compatible mapping scheme. Windows 95 and 98 drivers use UltraSound.INI to load the patch files on demand. In DOS, the loading of the patches can be handled by UltraMID, a middleware TSR system provided by Gravis that removes the need to handle the hardware directly. Programmers are free to include the static version of the UltraMID library in their applications, eliminating the need for the TSR. The application programmer can choose to preload all patches from disk, resizing as necessary to fit into the UltraSound's on-board RAM, or have the middleware track the patch change events and dynamically load them on demand. This latter strategy, while providing better sound quality, introduces a noticeable delay when loading patches, so most applications just preload a predefined set.

Each application can have its own UltraMID.INI containing a set of patch substitutions for every possible amount of sample RAM (256/512/768/1024 kB), so that similar instruments are used when there is not enough RAM to hold all of the patches needed (even after resampling to smaller sizes). Unused instruments are never loaded. This concept is similar to the handling of sample banks in digital samplers. Some games — including Doom, Doom II and Duke Nukem 3D — come with their own optimized UltraMID.INI.

The UltraSound cards gained great popularity in the PC tracker music community. The tracker format was originally developed on the Commodore Amiga personal computer in 1987, but due to the PC becoming more capable of producing high-quality graphics and sound, the demoscene spilled out onto the platform in droves and took the tracker format with it. Typical tracker formats of the era included MOD, S3M, and later XM. The format stores the notes and instruments digitally in the file instead of relying on a sound card to reproduce the instruments. A tracker module, when saved to disk, typically incorporates all the sequencing data and samples, and typically the composer would incorporate their assumed name into the list of samples. This primitive precursor to the modern sampler opened the way for Gravis to enter the market, because the requirements matched the capabilities of the GF1 chip ideally. The problem with other sound cards playing these formats was that they had to downmix voices into one or both of its output channels in software, further deteriorating the quality of 8-bit samples in the process. An UltraSound card was able to download the samples to its RAM and mix them using fast and high-quality hardware implementation, offloading the CPU from the task. Gravis realized early on that the demo scene support could be a sales booster, and they gave away 6000 cards for free to the most famous scene groups and people in the scene.

As the GF1 chip does not contain AdLib-compatible OPL2 circuitry or a codec chip, Sound Blaster compatibility was difficult to achieve at best. Consumers were expected to use the included emulation software to emulate other standards, an activity not necessary with many other cards that emulated the Sound Blaster through their sound hardware. The emulation software ran as a huge TSR that was difficult to manage in the pre-Windows days of complicated DOS extenders.

Although there was native support for many popular games that used middleware sound libraries like HMI (Human Machine Interfaces) Sound Operating System, the Miles Audio Interface Libraries (AIL), the Miles Sound System or others, the user had to patch the games by replacing the existing sound drivers with the UltraSound versions provided on the installation CD. Also, the UltraSound required two DMA channels for full-duplex operation, and 16-bit channels were generally faster, so many users chose to use them, but this led to errors for games that used the DOS/4GW DOS extender, which was common in the UltraSound's era.

The two principal software sound emulators included with software package were:

• SBOS, Sound Board OS — Sound Blaster Pro 8-bit stereo emulation and AdLib FM synthesis. It was a real-mode software emulator that recreated the AdLib's OPL2 FM synth chip and required that the user have a 286 processor or better. There were special versions for the UltraSound MAX (MAXSBOS) and AMD InterWave-based cards (IWSBOS), which made use of the CS4231 codec chip instead.
• Mega-Em — advanced emulation software that required at least a 386 processor and EMM manager with DPMI/VCPI support. Mega-Em emulated the 8-bit Sound Blaster circuitry for sound effects and the Roland MT-32/LAPC-I or Roland Sound Canvas/MPU-401 for music. It supported UltraMID TSR functionality.