Product specifications

Design Guide - VT82C694X Apollo Pro133 with VT82C686A
Preliminary Revision 0.5, November 19, 1999 61 Motherboard Design Guidelines
Technologies, Inc.
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2.5.2 AC’97 Link and Game/MIDI Ports
Table 2-13 shows a brief description of the signals of AC'97 Link Controller and Game Ports. All those signals are multi-function
pins with the second IDE channel bus. To enable both functions, the power up strapping of SPKR (pin V5 of the VT82C686A)
must be pulled up to VCC3 with a 4.7K~10K ohm resistor.
Table 2-13. Signal Description of AC'97 Link and Game/MIDI Ports
Signal Name I/O Description
BITCLK (SDD0) I AC'97 Bit Clock
SDIN (SDD1) I AC'97 Serial Data In
SDIN2 (SDD2) I AC'97 Serial Data In 2 (reserved)
SYNC (SDD3) O AC'97 Sync
SDOUT (SDD4) O AC'97 Serial Data Out
ACRST (SDD5) O AC'97 Reset
JBY (SDD6) I Game Port Joystick B Y-axis
JBX (SDD7) I Game Port Joystick B X-axis
JAY (SDD8) I Game Port Joystick A Y-axis
JAX (SDD9) I Game Port Joystick A X-axis
JAB2 (SDD10) I Game Port Joystick A Button 2
JAB1 (SDD11) I Game Port Joystick A Button 1
JBB2 (SDD12) I Game Port Joystick B Button 2
JBB1 (SDD13) I Game Port Joystick B Button 1
MSO (SDD14) O MIDI Serial Out
MSI (SDD15) I MIDI Serial In
2.5.2.1 AC'97 Link
An AC'97 Controller is integrated in the VT82C686A and currently supports only one Codec. One Primary Codec (ID 00) is
completely compatible with existing AC'97 definitions and extensions. The Codec ID functions as a chip set select. For more
details, refer to the AC'97 Component Specification Revision 2.1.
AC-link is a digital serial link between the AC'97 Controller and AC'97 devices. AC-link signals are multi-function pins with the
Second IDE channel bus (SDD[0..5]). A linking example between the AC'97 Controller and one AC'97 Codec is shown in figure
2-54. A complete schematic for implementing the VIA VT1611A AC'97 Audio Codec is shown in Appendix B.