Hopefully this helps someone on google which can be redirected here or help those on this forum, the 10 sd rc1 commandments ha :
1) Try to buy the new compact sd card readers (old ones with long wire are put together with less quality than ones being sold now which are compact and plug right into serial port). Make sure a good connection is made though, maybe a piece of scotch tape on sd card reader end to plush the fit.
2) Best sd cards to use are 1-4 gb ScanDisc sd cards class 6 (blue sds). Many sd cards (like 32gb or non scandisc won't work).
3) Tell the users WHICH copy of Dreamshell cd such as DS RC1 or DS Beta 3 or Beta 4 to use with said game (sadly uploaders don't do this), for instance doom_dc seems to work with all Dreamshell versions but Sonic will not run on RC1.
IF you have bios chip in dc, you could simply install Dreamshell in your dc without the need of Dreamshell cd running anymore after that.
It would be cool if people buy the bios chips, then put Dreamshell on it, then sell on ebay with directions how to install.
4) When downloading the sd isos, NOT regular isos, read the description of sdisos on isozone.com and make sure the sd game works with the Dreamshell cd VERSION you have, example Sonic (and others) will work with Dreamshell Betas perfectly but will freeze up in Dreamshell RC1.
5) Only have 1 controller plugged in, pcwzd13 explained that some homebrews won't work and appear to be corrupted if the 2nd controller is plugged in during start of sd game, which helped me play a game finally =)
6) I also found out if a sd game "freezes" or if it works great once then you immediately restart dreamcast to play another game or same game on sd card and it don't work anymore, you don't need to reformat the sd, just let let the dreamcast and sd card reader "cool" for 10-20 minutes then restart the game and it'll work fine HOWEVER if you have 20 games on sd card like me, and you put another game on that doesn't work with DS RC1 and you get "the black screen of death aka black screen with white text with bottom reading DS$ help" then that game, and all of them...will be corrupt, so you will have to reformat sd card and put the games you know work back on it, usually 1-2 gb cards have this issue.
7) Hit the "A" button twice to select "run yes/no" sd, if you hit only once nothing might happen, so press A button on dc controller twice to see "run sd card iso" box in DS SD menu. Select yes and game will load and you can play it then.
8) If you have a sd card reader plugged into back of dc in the serial port, dreamshell rc1 cd, a scandisc sd card, put this (below game via link) on sd card either by itself or with other games from your pc to sd card, plug sd card in dreamcast sd card reader, it runs perfectly and is a perfect emu :
http://www.theisozone.com/downloads/drea...tor-sdiso/
9) Place to d/l sd card games which are sd isos NOT regular isos/cdi :
http://www.theisozone.com/downloads/dreamcast/sd-isos/
You can play some retail games (some run near or even perfect) converted to work with sd card and great "4th party" as I call them homebrews and even emus to play on sd.
10) Thank you to Swat for dreamshell boot cds and answering our questions and to the people making various dc sd card readers.