Anyone familiar with early 90s electronic music, especially video game music, has probably heard of the E-mu Proteus series. What isn't as readily known is that there was also a 4 MB sound expansion for the Proteus 1, and by a third party at that: ProtoLogic, by InVision Interactive.
In a nutshell, most of the Protologic ROM is dedicated to picking up where the sound ROM of the famous Proteus 1 left off, meaning additional pop-oriented sounds, most notably some synth pads, distorted guitars, some TR-808 samples, and a few ethnic percussion sounds. There are lots of mixed thoughts about how the Proteus 1 sounds without it, so in my opinion, this made it much more worth collecting, even if it is still constrained to the programming limits of the Proteus series (i.e. no easily-programmed filters). It comes with an additional 128 ROM presets to get started with as well, which makes having it for a Proteus 1XR all the more recommended since the XR series inherently has more RAM presets (a total of 512 presets combined!).
Alas, one reason why I'm making a big deal out of this: there is no modern software alternative to these particular sounds, not even from Digital Sound Factory. Aside from InVision being a third party sound developer, they faded into obscurity shortly after this came out, and even their sample CD's seem to have been better remembered despite many being based on other soundware brands of the time such as Sound Genesis and Northstar. The consolation: I've put in the effort of sampling the ROM as best as I could, and while I hesitate to publicly share my results in the event that the copyright owners are still around and take notice, know that some archiving of these rare sounds have been done, complete with an attempt of recreating the presets in SFZ format. I'm also considering dumping the firmware EPROM's, which, rest assured, I am more willing to share if I do for the sake of the longetivity of these rare units.
Thanks for reading!