The samples went in a different folder called 'samples' and if you didn't have the samples then you didn't get the analog sound. you take an audio recording of the analog sound (the sample) and just trigger the sample at the right places in the games. The old versions of MAME got around this difficulty by using 'samples'.
These were/are very difficult to emulate because the analog sounds were created using a combination of different components that interacted to make the final sound you hear.
Some of the older games use analog sounds.
