Missing sound effects on Lode Runner
jsmolina opened this issue · comments
Lode runner has missing sounds effects for 'laser', 'pickup money', ...
It has music effect for ending level, so I guess it's something related to samples.
Tried at 8 MHz and same disk image works perfectly on mini vmac.
already failing on latest versions
macplus was known to have 6522 VIA chip.
The sampled sound engine piggybacked on the video circuit. As the raster scan returned from the right side of the screen to the left, one byte of data was placed into a PWM generator instead of the screen. This provided 8-bit sampled monaural sound sampled at the 22.25 kHz horizontal blanking rate. General purpose 6522 outputs could mute the sampled sound, or set its volume to one of 8 levels of attenuation.
A square wave generator was included on the 6522. One of its two timer circuits could be set to toggle the mute output periodically. This could produce frequencies higher than 11 kHz.