On an attack/decay/sustain envelope generator (no release)…what function does a “square/normal” option have? Seen this on an early custom Moog module and assume its for the decay to produce organ type envelope when set to square? or am I way off? Wouldn’t the sustain do that?
You’re not way off, you’re actually right. The sustain at maximum would do the same, but…
The “square” position instantaneously and temporarily sets attack time to zero, decay to zero and sustain to maximum regardless of the knobs positions.
Full gate on, full gate off for each key stroke.
“normal” returns control of attack, decay and sustain to current knob values/position without having had to move any of the knobs.
If I’m not mistaken…
Many thanks for the answer, I guessed right ! I suppose its a function now deemed superfluous as I’ve not seen it on any EGs modules I’ve seen up to now.
The Moog Voyager has a similar switch, called “env. gate”, if I’m not mistaken.
No, not really… the env.gate switch is used to switch from a keyboard triggered gate signal to an external gate signal. When you trigger either of those, EG’s are triggered and they perform their function as per knob settings.That’s on the OS. Regular Voyager should be the same, but depending on the preset values.
Ooops, my mistake… 
It’s been too long since I had my Voyager Old School…
Sorry. 
But…there is such a switch on the Moog MG-1. It has 3 positions: Contoured, Keyed, Continuous. Contoured = normal, Keyed = square, Continuous = sustain/drone. And that I am sure of. 
(on the Moog Rogue it has Contour, Keyed, Bypass labeling)
Hey don’t worry, you know stuff. On the knowledge scale, you are far ahead 
Thanks. Now you’ve got the proof that I’m not a bot trying to pass itself as a human, nor am I really an alien either ! 