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. Compatibility 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