Currently Being ModeratedJun 19, 2012 2:57 PM (in response to Jim Mcdade)
The PowerBook 520c has built-in Ethernet, so that could be one way of transferring files. You would need an external AAUI to RJ-45 transceiver (such as the Apple Ethernet Twisted-Pair Transceiver) for this. Depending upon the exact operating systems involved, it may or may not be possible to set up file sharing between the PB 520c and more modern computers.
See also the following link.
The simple server solution in the last message there should not be too difficult to use.
It is not merely a question if transferring files though. You would have to check whether programs on the modern Macs are capable of correctly opening the file formats used. If necessary, try to re-save (Save As) into a generic format (Plain Text, RTF, et cetera) already on the 520c.