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VDP Register 1 bootup issue #43
The unmodified Sonic's Edusoft rom will fail to run under pretty much all of the emulators safe for the ones that require a BIOS and do not manually set the VDP bits.
He did comment and say that someone should check the value all the BIOSes out there set that bit to.
Also somewhat unrelated but MEKA sets the VDP registers back to default values, regardless of the BIOS you are using.
VDP Register 1 with the following BIOSes (Tested under SMS Plus GX, as i couldn't get most of the BIOSes below to boot a game on MEKA, bar the one that comes with it...):
Seems to be consistently 0xE0 and i can confirm setting VDP Register 1 to 0xE0 does allow the game to boot.
Why was it set to 0x80 ? SG-1000 stuff ? Megadrive perhaps ?