https://www.reddit.com/r/dreamcast/comments/1bbjevo/reverse_engineering_the_va2_dreamcast_trying_to/?sort=new
For the past few months, I've been reverse engineering the VA2. I have a unit from December 2000, which cannot play CDI, MIL-CDs, or burned CDI games. The change in the BIOS to v.1.022 happened in late November 2000.
However, after a lot of exploration, I was able to figure out that it's completely vulnerable to GDI images and burned GDI games. That is a huge security vulnerability that Sega forgot to patch out, and had the Dreamcast lasted into 2002, I'm sure Sega would've made a VA3 to prevent the hack that I did.
With that, seeing how the VA2 is vulnerable to GDI images, I think it is very well possible for a GDEMU converter to be developed for it. I discovered after a lot of playing around that the VA2's drive controller sockets are (very surprisingly) the same as the VA1's, and that the ribbon cable is what transfers the game's data to the motherboard.
What I need to do is somehow make a converter of the Dreamcast VA1's 50-pin BTB socket convert to the VA2's 16-pin ribbon cable socket. Despite that, I'm trying to learn KiCad but I can find so little schematic information on these 25-year-old parts, and I'm terrible at drawing schematics. I'm doing this VA2 project as a freetime hobby & for hardware preservation.
Here are my 3 blog posts that I wrote in Hungarian for myself (easily auto-translatible to English) and it describes the process how I defeated the seemingly non-existant GD-ROM security for the VA2. It's in chronological order, where I discovered more of the VA2 over time. Very important to read it all if you want to develop something like I have in mind:
Blog post #1 (02 04 2024): https://albalog.blog.hu/2024/02/04/va2_dreamcast_a_sa_made_in_china_kepe_2000_december
Blog post #2 (03 06 2024): https://albalog.blog.hu/2024/03/06/a_titokzatos_sega_dreamcast_va2_revizio_alapos_felfedezese_resz
Blog post #3 (03 10 2024): https://albalog.blog.hu/2024/03/10/a_titokzatos_sega_dreamcast_va2_revizio_alapos_felfedezese_resz_645
Both the VA1 and VA2 are also 3.3 volts and I'm playing my VA2 with the VA1's laser drive mechanism (several hours straight several times). Now I need some real help trying to make a prong converter like the image I attached.
My blog posts show that the patched v.1.022 BIOS won't be an obstacle at all for loading GDI games, it just wont be able to load CDI images. Theoretically, the 50 pin versus 16 pin socket conflict is the only obstacle preventing a GDEMU or hard drive converter from being developed.
If you want to take a go at developing my idea, I'd be happy to answer any questions during your development process as I have a VA2 last batch on hand for me to check things.
1: GD-ROM activation switch
2: Generic 4-pin JST connector (not needed for converter as it just powers a disc drive)
3: Genetic 2-pin JST connector (not needed for converter as it just powers a disc drive)
4: Common 16-pin socket between VA1 and VA2 (transfers game data through ribbon cable & what the 50-pin BTB socket needs to go into)
