Sharp MZ-800 - (3) Noise generation; (4) Setting tone volume

2nd byte
[27]0e[0s.nelps[p2[o11 be
x |
0 Frequency (high six bits)
Frequency = (3.55 x 10°)/(32 x n) kHz
n is a 10-bit binary number represented by DO to D3 of the Ist byte and DO to DS of the 2nd byte.
(3) Noise generation
Synchronous noise or white noise can be generated by outputting the following 1-byte data to the 1/O
port.
[p76 ps] p4/pa{p2 {D1 bo|
[1 |Reg. select | x | | [Frequency
Noise type
* The noise type is specified by D2.
0: Synchronous noise wane?
1: White noise Ct, 4 a>
* The noise frequency is set by DO and D1. The noise frequencies which can be set by DO and
D1 are as follows.
(D1 DO| Frequency
0 | 0 | 6.93 (=3.55 x 103/512) kHz
0 | 1] 3.47 (=3.55 x 10°/1024) kHz
1 | 0} 1.73 (=3.55 x 10°/2048) kHz :
1 | 1 | Same as that for the sound generated by tone generator #3. e :
cick JU
ail is lif
Synchronous
, noise | neers! Ea;
HULP (Duty 6.25%)
* When white noise is specified, the output waveform is composed of random patterns and a sound
with virtually the same spectrum as white noise is generated.
* When noise modes 0, 1, 1 are specified, the frequency is given by the following formula and a low
pulse tone can be generated.
f = N/32 x n x 16
* Ifyou specify tone 2 output in the noise mode specification, you must turn the output of tone 2 off.
(4) Setting tone volume
D7 | D6 | Ds | D4 | D3 | D2| D1 | DO
Reg. select Attenuation