Audio Generator

A native DOS program that generates sine, square, triangle and sawtooth
waves from 20Hz to 20KHz.

Uses the parallel port - doesn't need a sound card.

Requires an R-2R network on the first parallel port (378h) as follows:


        Pin 2 -- R --*-- 2R -- Pin 18
                     |
                    2R
                     |
        Pin 3 -- R --*
                     |
                    2R
                     |
        Pin 4 -- R --*
                     |
                    2R
                     |
        Pin 5 -- R --*
                     |
                    2R
                     |
        Pin 6 -- R --*
                     |
                    2R
                     |
        Pin 7 -- R --*
                     |
                    2R
                     |
        Pin 8 -- R --*
                     |
                    2R
                     |
        Pin 9 -- R --*-- C --> Audio out
                     |
                    2R
                     |
        Pin 18 ------*-------> Ground


Use resistor values of R = 10K and 2R = 20K

Use a capacitor value of C = 1uF (monolithic ceramic ot tantalum, + to pin 9)

Will operate in Win9x but timing restrictions will lead to distortion in waveform

The user interface is pretty basic, using function keys to select frequencies,
waveforms and amplitudes.  But we are more interested in the output (aren't we?)

Programmed in C++ with an embedded assembler routine to generate the waveforms
from lookup tables - needed to get high frequency performance.

Did this one mainly for the challenge of seeing if it could be done this way.
Does work and is useful.  Be careful of loading the output - high impedance line level only

A fancy windows version using the sound card is coming....