Specifications

PC/II+p Board Technical Reference Manual 68

7.24 South Bridge

See Bus, DRAM Memory, Peripheral Controllers, Section 7.2.

7.25 Speaker Output

Output sound waveform signals carried by the Speaker Output signal are generated by Timer 2. The speaker

output is controlled by the Speaker Control register in the ALI M1543C (register index 0B3h) which also is

available at the standard (ISA compatible) I/O port 61h – bit 1 provides enable/disable control of the speaker

output. The state of Timer 2 output can be read from port 61h, bit 5.

A conditioned speaker output signal, MS-SPEAKER, is provided on the Mass I/O Connector, J904, on pin

a7. This signal is intended to drive a piezo-electric audio transducer connected between the Speaker Output

signal pin and Ground. A conditioning circuit is included on-board.

A pinout of the Speaker interface is given in Table 36

For more detailed information, please refer to the Acer Laboratories M1543C datasheet, found in section 2

"Reference Documents" in this document.

7.25.1 Speaker Interface Pinout

Table 36 Signals – J904 – PC Speaker Output Interface

PIN NAME PIN# SIGNAL NAME SIGNAL DESCRIPTION

MS-SPKROUT

a7 Conditioned

Speaker Output

This signal is used to control the PC Speaker and

should connect to a piezo-electric transducer.