The PC Engine is a video game machine which was released in 1987 in Japan. Over the lifespan of the machine, there were several versions of the hardware, including two revisions of the CPU (which also contains the PSG sound generator). The two revisions of the CPU are:
- Hu6280, included in the original white PC Engine, and most other iterations of the hardware throughout its lifetime
- Hu6280A, included with the SuperGrafx and apparently some CoreGrafx machines.
One of the differences between these two chips was the sound - and the principle difference in the sound that I'm aware of, was the presence or absence of a "pop" sound on occasion.
This program generates a constant (although somewhat annoying) tone on the output, and allows the user to turn on/off the following attributes in order to determine the nature of the 'pop' sound, and when it is generated:
- Button I: set channel balance to 0/0 (15/15 when released)
- Button II: set global balance to 0/0 (15/15 when released)
- 'Down' button: set global volume level to 0 (31 when released)
- 'Select' button: turn channel off (on when released)
The output can be captured on an oscilloscope or in an audio capture program such as Audacity.
Outputs were found to be as follows:
"pop" sound occurs, and shows as though the waveform is entirely above the center line initially - a DC offset (but later drifting back toward center). This has the effect of the initial waveform's impulse being double what it should be, but the waveform peak-to-peak is not.
- compile with the flags '-t -v -v -ADEPRECATED=1' if using version v3.99 or greater of the HuC compiler
Use this information and software at your own risk.