I bought the Nexus 16mg card and had all sorts of problems. Took me hours to figure it out... and then, all of a sudden, it worked. So I've compiled a list of all the possible things that could go wrong. I'm assuming your 4mg card is pretty much the same as my 16mg card. If you go through this entire list, and you still can't get it to work, then I think you're fucked. You got yourself a defective product (and from this forum, it seems there's a lot of them floating around). Hope you can return it.

A. First check to see if your Nexus can act like a NORMAL memory card.
1.) Begin with your card unattached to anything.
2.) Turn on your Dreamcast without any games in it and with one Sega controller attached to the first input. You should see your Dreamcast menu.
3.) Gently slide the memory card into the controller into Slot 1 (the top slot). Wait 30 seconds before doing anything. If you see the lights flashing (4mg) or the numbers flickering (16mg), DEFINITELY DON'T do anything. Sit and be patient. I don't think this is a perfect product, so you got to be nice to it. Tell it, "You're doing a good job" in soft tones. On your Dreamcast menu, go to Files. See if you can access your memory card. If you can get into it, and it shows that you have nothing or something on the card, you're in good shape. Slide in another memory card into Slot 2 and try copying a file to the Nexus and vice versa. Try deleting all the files. Try playing a game and saving a file onto your nexus. If your nexus card acts like a normal memory card, you're in really good shape. (Skip to Section B)

MY DREAMCAST SAYS MY NEXUS HAS ONLY 200 BLOCKS. WHAT'S WRONG?
This is normal! Don't think of your 4mb nexus as having 4mb of memory. Instead, the 4mb nexus is 4 SEPARATE 1MB cards combined into one card. The 16mb card is 16 SEPARATE 1MB cards combined into one card. You can access only 1MB at a time! When you first get your Nexus, it is on "Page 0". The Dreamcast (AND the computer) will say your memory card is only 1mb long (only 200 blocks of memory). In order for you to "change Pages" you have to press that button on the Nexus card. Once you let go of the button, it will begin to load the card. THIS TAKES 30 seconds. DON'T do anything while it's loading up or you will "confuse" your Nexus (especially if lights are flashing or digits are flickering). If you want to go from "Page 0" to "Page 3", you push the button 3 times quickly (as SOON as you stop for half-a-second, it will start loading that page. While it's loading, I wouldn't try pushing the button or you risk fucking up your card. So if you were trying to get to "Page 3" but the card started to load "Page 2" because you didn't push the button fast enough, just wait until "Page 2" loads up. When it's done, press the button one more time to get to "Page 3").

HOW DO I KNOW WHAT "PAGE" I AM ON?
For the 4MB card, it depends on the lights:
Page 0 = Both lights on;
Page 1 = Left (Red) light only;
Page 2 = Right (Green) light only;
Page 3 = Both lights off
For the 16MB card, the LED display will tell you:
Page "0,1,2,3,4,5,6,7,8,A,B,C,D,E,F"

Remember, each "Page" has only 1MB of memory, and neither the Dreamcast NOR the Computer can access other pages. You have to manually push the button to "switch" pages, and then, all of a sudden, the Dreamcast will "think" you've put in a new card. As
soon as you let go, it will LOAD that card. It is important that you not get impatient. This "loading" process could take 30 seconds. (the numbers should be flickering). Wait until it has fully loaded before trying to do something (note that when your card is loading, the dreamcast will act like there is no card, or the card will flash on and off and not let you access it). This might be superstitious, but before you switch "Pages", I would exit out Files to the Dreamcast main screen. You don't want the Dreamcast trying to access the card while you are still switching pages.
Again, each "Page" is a SEPARATE memory card. So don't post on this forum "I saved something on my Nexus, and all of a sudden, It'S GONE!!!). Chances are, you've saved it on another page. Just press the button and WAIT, and go from page to page until you find it.

PROBLEMS:
If you're Dreamcast doesn't recognize your Nexus as a memory card, try these one at a time:
-When the Nexus has stopped loading, pull the card out. Push it back ALL THE WAY, so that you're sure it won't go any farther. Try again.
-When the Nexus has stopped loading, pull the card out, and put it into Slot 2. Try again.
-When the Nexus has stopped loading, Pull the card out. Shut off your Dreamcast. Slide your nexus into the controller. Turn on your Dreamcast. Try again.
-Use a different controller. Try again.
-Try all of the above combinations on different controller inputs.

4.) If, after all of this, and your Dreamcast still doesn't "see" your Nexus, then you have a problem. Or if you have a 16mg card and see on the LED display an "E." Then you have to reformat.

The Deadly "E" or ERROR sign.
I see a lot of complaints about the ERROR sign. I never got it, so I don't know. I suspect it means you're fucked. This is what people seem to be saying. If you get that error, sign, you basically have to reformat your card. Make sure that your Nexus is NOT plugged into your computer. Try the above directions one more time just in case. When you reformat, you lose all the memory on the card. If you just got your nexus, then it doesn't matter, since you don't have anything saved on it yet.

If your dreamcast still doesn't recognize the card, then gently pull it out. Turn off your Dreamcast. Turn it back on. When you see the main menu, hold down the button on the card, and while you're holding it down, slide the card back into the controller. As soon as you hear the card click into the controller, let go of the button. It is now reformatting your card. Don't do anything. Sit and be patient. The poor thing's working. When the lights have stopped flashing (4mg) or the numbers on the card have stopped flickering (16mg), try to access the card through your dreamcast. If it says your card is empty, I think you're in good shape. Try using it as a normal memory card (via directions above).

Now, if you get the "E" again, then I think you're fucked. At least for that megabyte. Push the button ONCE. And wait 30 seconds (while it's flickering) .On the 16mg card, the number should change from 0 to 1 or 1 to 2. The numbers go 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F. Now repeat the whole process again with that new megabyte. If you get the "E" on one of memory sections of your card, try repeating the steps on another section of the card. Hopefully, you'll only have one defective section out of 16. Remember that number, and make sure you never save anything on it. For the 4mg card, you don't have a LED display, but you can still reformat your card the same way.

If you've tried all of this, and you still can't get the dreamcast to detect your card, then you probably have a defective Nexus. Don't bother trying to hook it up to your computer. It won't matter how many files you download into your nexus, if your Dreamcast can't read it. Try the following as a last resort, one at a time:
-Try your Nexus on someone else's Dreamcast.
-When the Nexus has stopped loading, pull the card out, blow (not spit) away imaginary dust at the input ends. Push it back in and try again.
-When the Nexus has stopped loading, pull the card out. Give it a good flick. Push it back in and try again.
-When the Nexus has stopped loading, pull the card out, drop it from a height of 4 inches onto something hard. Push it in and try again.
-Turn off your Dreamcast. Give the card it good flick while it's in the controller. Turn the Dreamcast on.
-Shout really loud, curse and threaten your Nexus card. Try again.
-Return your card for a replacement.
-Send irate email to sale@hkems.com. Threaten to register them with the Better Business Bureau.
-Write to the Better Business Bureau.
-Spam HKEMS mercilessly.

B. Setup your computer for interface with your Nexus. If you've gotten this far, then you're almost there!
1. Download the most recent software. Go to http://www.hkems.com and click on "Download" on the left column.
Download "241.exe"
Download "DC Linker V2.3B" (these are the most current as of this writing)
2. Unzip these files onto your Desktop (or wherever you want them).
3. Plug your cord into the Printer port of your computer.
4. Plug the cord into the back of your Nexus card.
5. Turn on your dreamcast. Wait for the menu to come up.
6. Gently slide your Nexus card (already attached to your computer) into your Dreamcast controller.
7. Start the DC Linker Program by clicking on "DCLink23.exe." On the Left side of the Screen, you should see "EMS, www.hkems.com, DC Linker V2.3b for ____________" Now just pray that it doesn't say "No Device".

8. On the lower left part of the screen you will see 5 buttons: File, Slot 1, Slot 2, Setup..., Exit. Click on the "Slot One" or "Slot TWO" button and then REFRESH and hopefully it will recognize your card. If you get an error, see below.

9. Once it recognizes your Nexus, it's a piece of cake. First, you press the "File" button and then click on "Open DCM File" Choose the "241.dcm" file which you should have downloaded.
10. Now push the "DCI" button on the lower center of your screen and choose the file you want to download into your nexus. The icons should appear in the "File" Box.
11. Now, you just click and drag the file to the box "Slot1" or "Slot2" part of the screen depending on whether your nexus is in Slot1 or 2 of your dreamcast controller (top or bottom)
12. This might be superstitious, but I would drag only one at a time for now. You don't want to freeze up your memory card and cause it to crash. Then you'd have to reformat it. Once you've downloaded it, close out of the DC Linker program.
13. Now, on your dreamcast menu, go to files, and look to see if it worked. If you see those icons on the screen, then congratulations, you've downloaded files to your Dreamcast!

C. Problems
More likely than anything, your DC Linker program probably said, "link error 1, please check Connection speed in Setup, DC power and cable connection". This is a list of possible things that might be wrong.

1.) On your DC Linker page, click on "Setup..." On the dial from "More Speed" to "More Compatible", you want to drag that bar all the way right to "More Compatible". Make sure the "Auto Refresh Mode" is checked. Then push OK. On the main menu, click on "Slot1" or "Slot2" (depending on where your nexus is) and click on "Refresh".

2.) If you still get the Link-Error, Push Exit. Restart the Program. And try again. Make sure the settings above haven't been changed to something different.

3.) You have to make sure that your Parallel Port setting in your BIOS is set to EPP or SPP: Close the program. Pull your Nexus out of the controller and shut off your Dreamcast.

Here you have to be REALLY careful. If you do something wrong, you could really fuck up your computer (and it would still be messed up even if you tried reformatting your hard drive). So go slowly. Take your time. And make sure there aren't any small kids around that might "accidentally" slam their hands on your keyboard.

Just remember, if you aren't sure whether you did something or not, always pick the option "Exit without Saving settings" and start over. It's better to try again, than mess up your computer. If you did something by accident, and saved it to your BIOS, you might have trouble trying to find how to change back what you did. However, most BIOS have an option called, "Default Setting" in which it changes back to the original settings. This might not help though, if your computer has gone through some changes since you got it.

OK. First, you close out of all operations. And then you Restart your computer or Shut Down and turn on your computer back on. Usually the first screen that comes on has the name of the company of your computer and "BIOS". You will usually see something that says "Press F2 for settings". Every company's BIOS is different - so you have to read what it says. My computer at home has me push the "DEL" button to enter the BIOS. Sometimes it's F1.

If you don't see anything, and then Windows boots up, then you're too late. You have to restart your computer again. Try pushing F2 or F1 or Del right when it boots up- that usually will bring you to the BIOS screen. If Windows boots up anyways, shut down your computer again. When you turn on your computer, hold Ctrl and lightly press down on all of the buttons of your keyboard with the palm of your hand (it's gotta be one of them). As soon as you see something happen, stop pushing any buttons. This is where you have to be really careful. (Again, if you think you might have done something unintended, select the option "Exit without saving settings" and start over again. On some computers, you have to press "ESC" to exit, and then it will give you the choice whether or not to save settings.)

Like I said, every BIOS is different. So I can't tell you exactly what to do. As long as you just push ONLY the arrow keys (up, down, left, right), it shouldn't change any settings - so you're free to explore the screen using these buttons.

You should see stuff like System Time and Date, Diskette A, B or Primary Drive... and a whole bunch of crap. Keep pressing the down arrow to see the complete list. You're looking for something called "Integrated Devices" or "Peripheral Devices" or something like that. When you find it, (or think you do), go down to that line and press Enter once. A new screen should come up with more crap. Now, what you're looking for is something like "Parallel Port". When you find this, press Enter Once. Now, you should be given a choice of the modes - either SPP or EPP or EPC or whatever. After you've pressed enter, you should be able to use the arrow keys to change it to "SPP" or "EPP". (If you have the choice between these, use SPP first. If that doesn't work, try EPP. But I think they are the same thing). Once you've changed it, press enter.

If you've gotten this far without changing anything else, you want to "EXIT and save changes". Sometimes you have to press one of the F-buttons (read what it says on the screen). If it doesn't say anything, then you probably should press Esc - and then it will give you the option of exiting with or without changing settings.

If you couldn't figure out how to do it, write down some of the things you saw on the BIOS screen, and post it here. Maybe we can figure out where you need to go in the BIOS (every BIOS is a little different).

When you do this, your computer should be rebooting again. When it does this, make sure your Nexus is plugged into the printer port of your computer - but don't plug it into your dreamcast yet.

(Note, when you do this, your computer might prompt you to reinstall the drivers for your printer. Don't panic. This won't mess up your computer or printer. Just do what it tells you to do).

Now first, make sure you've downloaded the most up-to-date version (I think 2.3B) of the linking program found on this website.
Next, turn on your dreamcast. Then slide the card into the controller (the cartridge is already plugged into your computer, right?). Do this slowly and gently NOT pressing that button on the top of the cartridge.

When you hear the click, sit and wait patiently. Don't press anything. The number on your memory card should be flickering. Whenever it's flickering - don't do anything. Just wait or risk fucking it up. If you see an "E", than I think you're fucked and you have a defective card. Read the directions above under "The Deadly "E" or Error sign".

Now start up the link program. And try it. Note, you have to download that DCM file first, I think. Then click on the "Slot One" or "Slot TWO" button and then REFRESH and hopefully it will recognize your card. (Make the settings are on "Most Compatible").

4.) If it doesn't work, pull your card out, shutdown your computer and go into the BIOS again to make sure you really saved it on EPP mode. Try again.

5.) Go back to your BIOS and try it on any other mode it has for the printer port.

6.) If it still isn't working, close out of the program. Pull your Nexus out of the controller (if it isn't "flashing" or "thinking"). Shut off your dreamcast. Shut Down your computer. Make sure the Nexus is attached to the Printer port of your computer snuggly. Turn on your computer. Make sure the printer port is back to EPP. When you see your desktop (and your computer has stopped "thinking"), turn on your Dreamcast. Gently push the card into the controller (it's already plugged to the computer, right?). Open the DC Linker program and try again.

7.) If it still isn't working, close out of the program. Pull your Nexus out of the controller. Shut of your dreamcast. Slide the card into the Controller. Turn on your dreamcast. Open the DC Linker program and try again.

8.) If it still isn't working, close out of the program. Pull your Nexus out. Shut off your Dreamcast. Shut down your Computer. Slide the card in. Turn on your Dreamcast and Computer at the same time. Open the DC Linker program and try again.

9.) If you still get that Link Error, try it on another computer. Maybe your computer is messed up. My computer at work does it OK, but not at home (don't tell them I did it at work!). And don't do it on company time. Nothing would be more stupid than getting fired for trying to do your Dreamcast thing at work.

10. ) If it still doesn't work, these are some last resort options:
-When the Nexus has stopped loading, pull the card out, blow (not spit) away imaginary dust at the input ends. Push it back in and try again.
-When the Nexus has stopped loading, pull the card out. Give it a good flick. Push it back in and try again.
-When the Nexus has stopped loading, pull the card out, drop it from a height of 4 inches onto something hard. Push it in and try again.
-Turn off your Dreamcast. Give the card it good flick while it's in the controller. Turn the Dreamcast on.
-Shout really loud, curse and threaten your Nexus card. Try again.
-Return your card for a replacement.
-Send irate email to sale@hkems.com. Threaten to register them with the Better Business Bureau.
-Write to the Better Business Bureau.
-Spam HKEMS mercilessly.

I've read other people saying that when you're done, you should pull the memory card out before you shut off your dreamcast. I think this is good advice. But make sure you don't pull out the memory card while it is "thinking". That could really confuse and fuck up the memory card.

If it actually DOES work, CONGRATULATIONS!!. But remember, these things aren't reliable at all. Constantly save everything to a "normal" memory card or better yet, onto your computer.

Well, good luck.