Specifications

CHAPTER 2

Hardware Design

Audio System 25

Audio IC 2

The Creative Vibra 16S IC provides 16-bit audio support. It is compatible with

Sound Blaster 16 and with Roland MPU401 UART (universal asynchronous receiver/

transmitter) mode. It also complies with Multimedia PC Level 2 speciﬁcations. The

device also has an integrated 16-bit SigmaDelta codec that handles ADP (audio digital

processor) inputs, ADP digital outputs, and DAC outputs.

The audio IC provides the following:

■ a 16-bit bus interface with the ISA bus

■ a digital audio processor (DAP) block that interprets Sound Blaster 16 commands and

provides downward compatibility with Sound Blaster products

■ a mixer block that controls volume and mixing functions

■ a joystick quad timer and data buffer that allow MIDI devices to be connected to the

GamePort without external TTL (transistor-transistor logic) support

For complete speciﬁcations, you should refer to the reference material provided with the

audio IC.

Sound Synthesizer Chip Set 2

This chip set consists of two ICs: the synthesizer and the digital-to-analog converter. The

Yamaha synthesizer is a YMF262 Type 13 OPL3 device. It uses FM (frequency

modulated) synthesis to generate sounds. The IC includes the following features:

■ 24 operators that can be conﬁgured in four-operator mode for six channels

■ 36 operators that can be conﬁgured in two-operator mode for 18 channels, or for 15

channels with ﬁve rhythm channels

■ eight selectable FM source waveforms

■ four channels of sound output

■ hardware vibrato and tremolo effects

■ two programmable times that can generate interrupt requests

Because the YMF262 outputs voice data as digital data, it is necessary to convert this

data back to analog form. This function is performed by the YAC516, a delta sigma DAC

with an eight times oversampling ﬁlter.

For complete speciﬁcations, you should refer to the reference material provided with

these two ICs.