YMF721 Datasheet, PDF (7/41 Pages) LSI Computer Systems – FM + Wavetable Synthesizer LSI

YMF721
(2) No ISA BUS Connect System
TXD
YMF7xx
(OPL3-SAx)
AUX2L
Lch
AUX2R
Rch
/OPLCS
/MPUCS
FSP
RXD
/PDIN
MCLK ^/PDOUT
BCLK ^CLKO
LRCK ^BCO
SDATA ^LRO
DO2
ARDY
RST
A2-0
/IOW
/IOR
ADB7-0
ABDIR
RESET
Note :
YMF721 (OPL4-ML2) has MPU401 UART in it. Thus, for the above case, TXD of YMF7xx (OPL3-SAx)
is connected with RXD of YMF721 (OPL4-ML2) and MPU401 port (/MPUCS) of YMF721 (OPL4-ML2)
is disabled so that YMF7xx(OPL3-SAx) sends MIDI data directly to YMF721 (OPL4-ML2).
The above system does not connect YMF721 (OPL4-ML2) and ISA bus, which is an example of Wavetable
upgrade solution represented by the Wavetable daughter card. Input pins of the ISA bus interface should be
pulled up externally. At this time, FM synthesizer/Command/Control ports are disabled, but the power
down function is enabled by receiving System Exclusive Message on the MIDI data, except that
Suspend/Resume function is disabled.
As a source of master clock for YMF721 (OPL4-ML2), use a crystal oscillator by connecting it to XI and
XO pins, or use the clock of 33.8688 MHz from the system. Connect BCO, LRO, DO2, /PDOUT and
CLKO directly to YAC516 (DAC16-L) as shown to convert serial data output to analog signal. Then, it is
recommended to input the converted analog signal to AUX2L and AUX2R of YMF7xx (OPL3-SAx) after
amplifying the volume of source of YMF721 through the gain of +12 dB as shown for the purpose of
equalizing the volumes of multiple sources.
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July 10, 1997