Apple Macintosh PowerBook 145 - Manual (Page 241)

Adding memory to your computer
Your PowerBook computer comes with at least 4 MB of RAM.
By adding memory upgrade cards you can increase your
computer’s memory. You can find out how much memory your
computer has by choosing About This Macintosh from the
Finder’s Apple menu.
Apple provides memory upgrades through its authorized dealers.
Memory upgrades are also available from other vendors; ask your
dealer for more information.
Apple recommends that memory upgrades be installed by an
authorized Apple dealer.
Your PowerBook computer also supports virtual memory, a
feature that makes use of hard disk space to provide additional
RAM.
Chapter 13: Expanding Your Computer System 225