YMF744B

5. Hardware Volume Control

The hardware volume control determines the AC’97 master volume without using any software control using the external circuit listed below.

Two pins, VOLUP# for increasing the volume and VOLDW# for decreasing the volume, are used.

Push SW

1k

VOLUP#

Push SW

1k

VOLDW#

1000p1000p

DS-1S provides a shadow register for the AC’97 master volume. When the software accesses the AC’97 master volume, it is always reflected in the shadow register.

Bringing the VOLUP# pin LOW level increments the left and right-channel shadow register by +1.5dB respectively. If either one of channel shadow registers have been already set to maximum value (00000b), the corresponding channel shadow register remains in the same value, and the other channel shadow register will only be incremented. If both of channel shadow registers have been already set to maximum values, they remain in the same values.

Bringing the VOLDW# pin LOW level decrements the left and right-channel shadow register by -1.5dB respectively. If either one of channel shadow registers have been already set to minimum value (11111b), the corresponding channel shadow register remains in the same value, and the other channel shadow register will only be decremented. If both of channel shadow registers have been already set to minimum values, they remain in the same values.

The master volume for the AC’97 is updated automatically via the AC-Link by setting corresponding values to the shadow registers.

When both of the VOLUP# and VOLDW# pins are at LOW level at the same time, the MUTE bit of the shadow register is enabled to automatically set the MUTE bit of the AC’97 master volume via the AC-Link. When either one of the VOLUP# or VOLDW# pins is at LOW level, mute condition of the AC’97 is deactivated via the AC-Link. At this point of time, the master volume is set to the value before the mute. When the AC-Link is busy (in case the register is controlled by the AC’97 Control Register), shadow register values will be set to the AC’97 on the next frame. At this time, BUSY is set at the AC’97 control register.

When the master volume is changed or muted depending on the logic level transition status of the VOLUP# and VOLDW# pins, an interrupt is generated at the host. The interrupt is used to notify the driver that the master volume has been changed.

When the AC’97 is not connected or it is placed in power down mode, the shadow register values will remain in the same even if the VOLDW# and VOLUP# pins are at LOW level.

February 3, 1999

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Yamaha YMF744B (DS-1S) specifications Hardware Volume Control
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YMF744B (DS-1S) specifications

The Yamaha YMF744B, also known as the DS-1S, is a popular audio chip that emerged in the late 1990s, particularly known for its use in sound cards for PCs. This sound processor exemplifies Yamaha's commitment to delivering high-quality audio through innovative technology and user-friendly features.

One of the standout features of the YMF744B is its ability to support advanced sound synthesis methods, including wave table synthesis and sample playback. These technologies provide users with a rich audio experience, enabling high-fidelity sounds reminiscent of live instruments. The chip is also notable for its ability to emulate MIDI instruments, allowing musicians to create synthesized music that captures the nuances of traditional sounds.

The YMF744B integrates a 16-bit DAC (Digital-to-Analog Converter), which facilitates high-quality audio playback with a sampling rate of up to 48 kHz. This capability ensures that sound reproduction remains clear and devoid of distortion, appealing to both casual users and audio professionals alike. Additionally, the chip supports multiple audio channels, making it ideal for gaming and multimedia applications where spatial audio is crucial.

Another significant feature of the YMF744B is its support for various audio formats, including PCM (Pulse Code Modulation), ADPCM (Adaptive Differential Pulse Code Modulation), and even MIDI. The versatility in format support allows users to interact with a broad spectrum of audio applications, from game design to music production.

The chip also comes with integrated Sound Blaster Pro compatibility, which significantly enhances its usability with a vast array of software and games designed during the 1990s and early 2000s. This compatibility is crucial for retro gaming enthusiasts who seek an authentic audio experience with classics from the past.

Moreover, the YMF744B champions power efficiency, making it an attractive choice for mobile computing platforms. Its low power consumption means that it can be effectively used in laptops without significantly draining battery life, allowing users to enjoy high-quality sound on the go.

In summary, the Yamaha YMF744B (DS-1S) stands out due to its advanced audio synthesis capabilities, high-quality playback features, and compatibility with multiple formats. These attributes make it a favored choice in the audio processing domain, continuing to impact computer audio technology long after its initial release.
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