Editing Gravis UltraSound (section)

===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 extender]]s.

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 [[Direct memory access|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 [[Intel 80286|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 [[Intel 80386|386]] processor and [[Expanded Memory|EMM]] manager with [[DOS Protected Mode Interface|DPMI]]/[[VCPI]] support. Mega-Em emulated the 8-bit Sound Blaster circuitry for sound effects and the [[Roland MT-32]]/[[Roland LAPC-I|LAPC-I]] or [[Roland Sound Canvas]]/[[MPU-401]] for music. It supported UltraMID TSR functionality.