Homebrew Question RetroArch Switch Questions for Sega CD emulation

[primetime]

So I have some sega CD games that I own but would prefer to emulate to preserve the disks. Questions highlighted in bold. Any help is much appricated.

So I tried the following:

Dark Wizard - format is cue/bin
Lunar 2 - Format was Tosec Iso, and the folder contained a ccd, img, and sub file. I used a software program called AnyBurn and it converted the img file into a cue and bin. It said there was 18 errors. So the Lunar 2 folder has 5 files in it which are the cue, bin, ccd, img, and sub file. I basically added the new cue and bin files to the old files within the folder.

Both folders containing the game files are located in the retroarch/downloads/Sega CD/

Here are my findings:

I went to load content/playlists/import content in the retroarch software itself and selected the Dark Wizard and Lunar 2 folders.
The software recognizes Dark Wizard in the playlist, but not Lunar 2.

If go to Load Core and select PicoDrive, and navigate to retroarch/downloads/Sega CD/ and select Lunar 2, it crashes.
If go to Load Core and select Genesis Plus GX, and navigate to retroarch/downloads/Sega CD/ and select Lunar 2, it loads and plays.
If go to Load Core and select PicoDrive, and navigate to retroarch/downloads/Sega CD/ and select Dark Wizard, it crashes.
If go to Load Core and select Genesis Plus GX, and navigate to retroarch/downloads/Sega CD/ and select Dark Wizard, it loads and plays.

So PicoDrive isn't working. PicoDrive is version 1.9 or something and the bios is like 1.5. Not sure if this is the problem?

I have the bios files in \retroarch\cores\system\

They are:

eu_mcd1_9210.bin
eu_mcd2_9303.bin
SegaCDBIOS9303.bin
us_scd1_9210.bin
us_scd2_9306.bin
bios_CD_E.bin
bios_CD_J.bin
bios_CD_U.bin


Dark Wizard shows up under Sega-Mega-CD-Sega-CD with the Core listed as PicoDrive which I found odd considering I scanned the Dark Wizard folder under Pico Drive as the core and under Genesis Plus GX as the core. Since it doesn't work under PicoDrive, I'd prefer if it was listed under Genesis Plus GX under the playlist so that I won't have to upload the Genesis Plus GX core each time and then navigate to the downloads folder every time. How do I fix this?

Also how do I get Lunar 2 to show up in the play list? It was also scanned in.

My lpl file in the playlist folder reads as:

{
"version": "1.4",
"default_core_path": "",
"default_core_name": "",
"label_display_mode": 0,
"right_thumbnail_mode": 0,
"left_thumbnail_mode": 0,
"sort_mode": 0,
"items": [
{
"path": "/retroarch/Downloads/Sega CD/Dark Wizard (U)/DarkWizard_U.cue",
"label": "Dark Wizard (USA)",
"core_path": "/retroarch/cores/picodrive_libretro_libnx.nro",
"core_name": "Sega - MS/MD/CD/32X (PicoDrive)",
"crc32": "B0C3C6BA|crc",
"db_name": "Sega - Mega-CD - Sega CD.lpl"
}
]
}

So what tool do I have to use to properly convert Tosec Iso format into cue/bin so that when I scan the game, it actually shows up in the playlist and I don't have to modify the lpl file by hand?
What is "crc32": "B0C3C6BA|crc" ? Is this code specific to Dark Wizard?

Lastly, how do I get thumbnails to show up?

Within this directory: retroarch\thumbnails\Sega_-_Mega-CD_-_Sega_CD-6817f2626b15f4022ab03795db6b0e4cf754bc74

I have the following files: Named_Boxarts, Named_Snaps, and Named_Titles. I have the software configured to show the box arts and titles, but the Dark Wizard box art and title isn't showing up when there is a Dark Wizard (USA).png file each each of the 3 folders, with each png file being a different file size. Do I have to move the Named_Boxarts, Named_Snaps, and Named_Titles folders directly into etroarch\thumbnails and get rid of the folder titled: Sega_-_Mega-CD_-_Sega_CD-6817f2626b15f4022ab03795db6b0e4cf754bc74 ??

Also can I zip up the Dark Wizard game folder containing the cue and bin files (or any other game folder) into a 7z file and have it scan properly with box and title art showing, or does each game have to have the game folder unzipped format in order to emulate?