The 3COM 3C509 is a nice, cheap, and reliable network card. It supports a link
       of 10 Mbps, full-duplex, over RJ45. Some models have additional connectors
       as well.
       
       === Plug & Play note ===
       The 3C509 can be configured either via a 'plug and play' mode, or manually.
       While the plug & play mode works most of the time on BIOSes that support it,
       it's worthless on other systems (esp. those that doesn't know aby PNP). On
       such systems the card's I/O port or IRQ might clash with other devices. In my
       case, the 3C509 card was using by default the I/O port 300h, that was already
       used by a MPU-401 interface.
       To configure the 3C509 manually, one need to use the 3C509CFG.EXE utility
       that is part of the 3Com EtherDisk #2 (3c509x2.zip). This utility allows to
       disable the PNP mode on the card (a hard reboot is required then for this
       setting to be applied on the card), and then it is possible to set the card's
       I/O port and IRQ manually. All these settings are stored in the card's EEPROM
       chip, so if the 3C509CFG doesn't work on one computer (I couldn't make it
       work on a 386SX for instance), it's not a problem to move the card to another
       computer, do the settings there, and then move back the card.
       
 (BIN) 3c509 Crynwr packet driver v116.zip
 (BIN) 3c509x1.zip
 (BIN) 3c509x2.zip