Vector 4 - Page 114

VECTOR 4
TECHNICAL INFORMATION
9.3 HOW THE TONE GENERATOR WORKS
Summary: The Tone Generator is located at U94 on the SBC. It is
76489 [.C. which can simultaneously generate three tones and white
noise, |
The 76489 is addressed using the port decoding scheme described in the previous
two sections. The actual port addresses are either 18H or 19H.
The tone generator is connected to an external speaker by two wires. This
connection is shown in Exhibit 1I-25. Refer to the Master Interconnecting Line
Diagram (Exhibit VI-9) for a complete illustration of all interconnecting lines.
The following chart shows some of the major features of the tone generator:
1. Each of the three tones is programmable for frequencies between 61 Hz and
62.5 KHz (up to 1024 steps for each tone).
2. Each tone can be one sixteen amplitudes (28 db range).
3. The noise generator can operate in either a "white™ or "periodie" noise .mode.
4, Each noise mode can operate in one of sixteen levels of attenuation. The
"white" noise mode can have its frequency controlled.
A complete description of the operation of this chip along with how it is
programmed is given in the VECTOR 4 PROGRAMMERS GUIDE. ~
09-01-82 7200-0001 I 5-23