You didn't mention which model of the Armada 7800 you have...go here for <a href="http://www.compaq.com/support/files/armada/us/index.html" target="_blank">downloads for the Armada Notebooks</a> . Select your model number...

Also, go here for <a href="http://wwss1pro.compaq.com/support/reference_library/viewreferencelibrary.asp?countrycode=1000&catid=76 3&famid=764&prodid=82|Armada%207800" target="_blank">manuals for the 7800 Series</a> .

Also, go here for the <a href="http://wwss1pro.compaq.com/support/reference_library/viewreferencelibrary.asp?countrycode=1000&catid=76 3&famid=764&prodid=82|Armada%207800" target="_blank">Quick Reference Guide (parts breakdown)</a> . Scroll down to the last page...it has your Memory Upgrade Chart.

Hopefully, you'll be able to find what you're looking for...Good Luck!