Memory Issue - Powerbook G4 1.5 Ghz

Old memory config was 256K lower slot, 256K upper slot for 512K.
When I added 1G to upper slot, system on recognizes total memory as 1G, say lower slot empty.
When I put the 1G in lower slot and 256K in upper slot, system tells me I have 512K, also say lower slot empty.
Any ideas as to why this is happening?

paulseto said:

Old memory config was 256K lower slot, 256K upper slot for 512K.
When I added 1G to upper slot, system on recognizes total memory as 1G, say lower slot empty.
When I put the 1G in lower slot and 256K in upper slot, system tells me I have 512K, also say lower slot empty.
Any ideas as to why this is happening?

Click to expand...

I'm not saying this is exactly what is happening in your situation paulseto, but I think you should read the info at the following links as it may answer your question:

Topic : Lower Memory Slot - Empty

Powerbook showing 256 Ram?

PowerBook Lower Memory Slot failure

OS X Updates Damaging PowerBooks Lower RAM Slot (Updated)

Powerbook G4 - Lower Memory Issue

Thanks Spawn Dooley,
Problem exactly! Never even thought I had two 512 cards! I bought this used PB for my daughter from a University Grad / now PC Programmer. It looked new, no scratches anywhere. Advised by seller that he had never opened PB memory door and I took his word for it. I was actually planning on adding two 1 Gig memory cards, but decided to put one in first and see how it ran. After reading the DT's, I don't know if taking the PB to Apple is even worth doing with the poor results. Maybe, just have to live with 1 Gig in upper slot and hope programs don't freeze. Again, thanks for your help!!!! Paul