Value 0×8000 means silence 0, 0xFFFF means +32767 and 0×0000 means -32768. So to convert to signed 16-bit PCM what for example WAV format uses, just toggle the high bit with XOR if I recall correctly. As a guideline, a single operator outputting sine or square wave at full volume results in min/max amplitudes of +4084 and -4085 (yes there is a off-by-one artifact in the output because of the way the chip perhaps handles sign and magnitude internally, the negative sample values are just got by inverting the magnitude bits).

Sampling rate is 49716 when rounded to nearest integer in case you are unsure what sounds the best.

I’ve been looking at Olli’s software today. I’ve been using the debugreader because I wasn’t certain that the OPL3 output was the same format as the YM3014 format. The YM3014 datasheet is explicit about it’s operation, but the YAC512 is much less so. Do you have details of the YAC512 format?

Now the question is did you modify/rewrote the software so it records raw PCM, instead of doing conversion from the YM3014 format?

However I later bought an USB logic analyser so I don’t have to fiddle around with custom hardware or software, it just captures everything for later analysis while real-time analysis is not possible unless I write a plugin for that.

I should point out that Jani had already said that in comment #4, I just wasn’t paying attention.

The data I collected last night was very noisy, but I’ve just been looking at the datasheets for the chip and it looks to me that the CLK signal is inverted in the OPL3 as compared to the OPL2. (The falling edge of LOAD corresponds with a rising edge of CLK) This would mean that I’m loading the shift register at the same time that the data is changing.

I built my device on a protoboard, so it’s easy for me to change. I’m going to use the last left over NAND gate to invert the clock and see if that fixes my problems.

I was mightily impressed by the microscope work as well. Many thanks to you, Olli