The Sega Dreamcast 4x Smart Nexus Memory Card is a revolutionary product that has a built in connection port allowing direct transferring of save games to/from your PC.
With 800 BLOCKS of memory and the ability to Upload/Download game saves from the Internet, and even edit your saved games to cheat the games with unlimited lives or health/ammo.
In the associated software download link, 92 "cheat" save games are included, for you to get started.
Thousands more available online free to download (check Deja.com in alt.dreamcast type groups for old downloads or archive.org).
NOTE: You need to have the memory card in the controller with the Dreamcast powered up and NO disc in the drive. You then plug the 6 pin connector into the card and the other end into your parallel port (or USB to parallel port adapter) on your PC and run the software. You need to have the Dreamcast fairly near the computer, or a long parallel extension cable. Uses parallel "printer" type port, so an older PC or a USB Parallel Port adapter is required (these are very inexpensive). ALSO: You must initialize/format all 4 memory banks before beginning to use the first time, or it will not work properly, and you will get an "X" on the Dreamcast screen. Press the button on the side of the card to switch between memory banks, and you will see the LED light inside will change color, and also the LED will turn off which indicates the 4th memory bank is being used.