Tandy 1000 HX - 2.3 Noise Generation

The frequency of each tone generation is calculated using
the equation:
f=N/32n
N = the clock input frequency
n = a 10 bit binary number [2 < n < 1023]
The divide by two counter is directly connected to a four
stage attenuator whose values and bit position in the data
word are shown in the following table:
ATTENUATION CONTROL
AO
0
0
0
0
0
0
0
0
Al
0
0
0
0
1
1
1
1
Data
A2
0
0
1
1
0
0
1
1
A3
0
1
0
1
0
1
0
1
Value
dB
0
-2
-4
-6
-8
-10
-12
-14
AO
1
1
1
1
1
1
1
1
Al
0
0
0
0
1
1
1
1
Data
A2
0
0
1
1
0
0
1
1
,A3
0
1
0
1
0
1
0
1
Value
dB
-16
-18
-20
-22
-24
-26
-28
OFF
Note: AO is the most significant bit of data
2.3 Noise Generation
The NCR Sound Generator has two (2) noise sources (periodic
and white), which share a common attenuator. These noise
sources are shift registers with an exclusive NOR feedback
network. One (1) of four (4) noise generator shift rates,
each rate being derived from the input clock, will be
controlled by the two (2) NF bits, as is shown in the
following table: