With a desire to increase the storage capacity of my Dreamcast, I have been trying to fit an internal SD card reader. Like so many other have before me. I've revised my circuit board three times now, making it more compact every time. And now I think I've reached the limit I can squeeze it down to. A little over 2cm x 2cm, it's a tiny thing, easily placed inside the console. With the SD card connector linked to it via several wires. Now, I'm happy with my circuit, as it is exactly what the original schematic shows. Only, I can't access any SD card I connect. At first I was just trying to boot DreamShell from it, but the boot disc says: "Can't find DS_CORE.BIN". I did get it to boot, once, and only once. I took the memory card out, after that successful boot to add a folder on the SD root. I didn't change any of the files inside the DS folder. And now it won't boot again. I've tried formatting the card, several times. Also, when I load DreamShell from disc, the OS sees the SD, but can't open it. in the "console" it says "Can't open dir: /SD" I don't understand what's going on, as it did boot, once. I've tried several cards now and the same issue every time. Any help would be great.
Recheck your wiring for shorts or for disconnected traces. In that small of package, it is very easy to miss a short, disconnected or wrong connection trace. If all that checks out and the issue is with several cards, it sounds like either the Dream Shell OS may be corrupt or else there is a problem with the Dreamcast. My machine won't let me do anything to the SD from Dream Shell other than access the SD card. Try the new Dream Shell 4.0 beta since it has these access issues sorted out. If you already have it, the issues are what I said above. There could also be a very unlikely chance that ALL of your SD cards are bad but that would be as likely as seeing a live dinosaur.
Problem solved. Sub-standard SD connector was the culprit. I took the SD slot out of my old PS3 and fitted that, and now it's working. Although, if Dreamshell encounteres a problem and crashes, I have to leave my console powered off for a while before it'll read the SD again. Other than that DreamShell runs fine off of SD.
