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. UltraSound ACE (Audio Card Enhancer) 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". UltraSound CD3 An OEM version of UltraSound Classic produced by Synergy, with 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. UltraSound Extreme 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. UltraSound Clones and OEM cards 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 onboard RAM by default, upgradeable to RAM using a SOJ-40 DRAM chip. Has a DIP socket for a boot ROM (optional) and an IDE interface (secondary). Synergy ViperMAX (GF1) - same card later repacked as UltraSound Extreme, but with only 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)