IIgs Rom 1 vs Rom 3

What is the difference between a Rom 1 and a Rom 3 Apple IIgs? I have 4 IIgs's sitting in my garage (law of aquisition... I wanted a IIgs for years, finally bought one, then I get 4 given to me for free!). It looks like I have two different styles (based on opening the lid and looking inside), one has a two rom chips, one has one rom chip (among other differences). I would guess they are Rom 1 and Rom 3 machines (I can tell by booting them right? the starting splash tells me? or how is it determined?). But what is the difference between a Rom 1 and a Rom 3 machine (besides a Rom 3 being newer I assume). Is one better than the other? What changes were made to the machines? (from the looks of the logic board, one of the two styles looks like it might have more ram on board... but maybe they just used a different chip and needed more of them... I don't know). Anywhere these details are listed out? I did a google seach, but didn't see anything fantastically helpful. So I am turning to the logical starting point to find this stuff out... the experts on classic computer hardware. Also, two of the four have a Ram upgrade board in it. All sockets are filled with chips, so how much Ram is that? 1mb? Or does it depend on the board and/or the chips (they are Apple branded boards). Are these upgrade boards usable in any IIgs (rom 1 or rom 3), the slot for it is in both style logic boards, so I would assume it works for both... but before I go swapping them around and frying something, I figured I would ask. TIA -chris <http://www.mythtech.net>