RAM upgrade / replacement possibilities

I am rehabbing my Dad's old ~2006 Asus W2P behemoth laptop (Mod: W2PB-7K003C). It officially supports 2GB RAM although Belarc states 4GB maximum. It apparently was shipped with 1GB installed. That is probably the default configuration. It is still running W7 sp1. Someone (probably my Dad's "Computer Guy" who runs a small independent shop) has added a 2GB stick to the RAM slot accessible by removing the small cover on the underside of the laptop. Investigation by various means reveals that the system is recognizing 3GB with 2.75GB "usable", with 1GB in slot 'DIMM0" and 2GB in slot "DIMM1". Clearly, the easily accessible slot is DIMM1 but there is only a single slot bracket on the MoBo as accessed from the underside cover opening. I have an old Dell running W7 that only recognizes 3.75GB of the 4GB installed - so I am aware of that basic limitation in some old systems.

So: is DIMM0 soldered RAM, or is it a bracket that allows a RAM stick to be replaced but is only accessible on the other side of the Motherboard - requiring an extensive dissembly to get to it?

From what I have gleaned: Belarc, CPU-Z, W7 "System" report, etc do not reliably indicate if memory is soldered to MoBo or not, only that the system recognizes RAM installed in different channels. If the maximum total RAM was designed to be 2GB - then it makes sense that the 1GB RAM it shipped with would not need to be accessed - the only possible upgrade would be another 1GB stick in DIMM1 thus prducing the ostensibly optimal dual channel configuration for maximum memory.

I cannot figure out when soldered memory became a common 'thing' with manufacturers. I don't think it was as far back in 2006. Your W2W guide doesn't mention RAM upgrade and none of the pictures clearly show if there is a RAM bracket on both sides of MoBo. I think the W2W is close enough to my W2P for comparison. I cannot find any info on my MoBo, or even any good pics of it, and nearly zero info on the computer itself. I guess bc it is so old and was overshadowed by the "Lamborghini" model Asus released about the same time with similar capabilities.

Yes, it's ooooold, but it's also still working. It's pretty amazing the number of ports, etc - it even has an on-board analog/digital TV tuner with a supplied remote control. But I may just end up using it as an experimental Linux system. Adding 1GB of RAM is so cheap that I might as well add it if it's possible.

Any help greatly appreciated.