Yamaha YMF7xx
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YMF7xx are audio contollers for personal computers. Chip marking for ISA bus cards ends at 719, and PCI begins from 720. Chips for PCI bus standalone adapters are marked like YMF7x4, while on-board or embedded solutions bear marking YMF7x0. YMF7x4 features semi-hardware XG MIDI synthesis with either 32- or 64-note polyphony, full-duplex playback and recording at any samplerate (internally upsampled to 48,000 Hz), external game controller and MIDI interface, and a legacy block for DOS application support.
YMF7xx chips were used in a lot of cheap (under $50) soundcards. Yet their performance was surprisingly good. The cards were usually equipped with good quality 18-bit Digital-to-Analogue Converters, providing low noise and harmonic distortion levels found in semi-professional hardware.
The XG synthesizer features not only basic XG System Level 1, but also part of MU-50 additions, and can reproduce most musical data previously programmed for the popular DB50XG daughterboard. The card shipped with a 2MB wavetable bank of 8-bit samples by default, which has to be loaded into system RAM during booting. Neither the resolution or content of the wavetable bank are hardware limitations. An user can load his own banks using third-party tools to further improve sound quality or completely change the set of instruments. As most other XG standard tone generators, YMF7x4 can swith itself into TG300B mode, which is an emulation of Roland GS standard in order to provide reasonable playback of musical data bearing GS logo.
Legacy support includes OPL3 FM synthesizer, Sound Blaster Pro (22 kHz 8-bit Stereo) emulation and MPU-401 compatible MIDI interface. In addition to OPL3, DOS applications running under Windows 98 can also use the XG tone generator.
All of these features are available using Yamaha VxD driver under Windows 98. WDM drivers for this operating system and later Windows 2000/XP provide unacceptable XG MIDI synthesis (General MIDI is somewhat O.K), and may lack important mixer controls, like separate Line-Out and 3D Wide (which should be turned off). There is no legacy mode under NT-based OSes.
The most advanced version is YMF754, featuring an 4 channel output. Most expensive and feature-packed soundcard on it is the XWave 6000. It has additional hardware chip to emulate 5.1 sound, and 6 channel amplifier (2W for each channel). It occupies two PCI slots.
