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3-7-2.
keyboard Buzzer
The NEWS series keyboard features a built-in buzzer which can
be buzzed by a signal from the system unit.
In the
NWS-1500,
the external oscillator circuit is activated when the
keyboard buzzer port is accessed, producing the sound of a
buzzer.
The buzzer frequency is different depending on
whether the port is read or write accessed.
With READ, the
tone produced is approximately 2.2kHz, with WRITE,
approximately l.4kHz.
A flowchart of this process is given
below.
<CPU>
<MEMC>
KB - Buzzer
address output
AS= "L"
R/W output
PORT output
DSACKO
AS= "H"
< CDECR >
<PARK>
IOSEL output
'---~
KBTX output
<On
<Oscillator
DSACKIO output
shot>
circuit>
Read
Write
2.2K
1.4K
~--
IOSEL negated
End of cycle
~--.
KBTX/
DSACKIO negated
NWS-1510/1530/1580
3-39
KTXD
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