Question to sfc experts:

Somebody addressed to me that the game Deae Tonosama Appare Ichiban refuses to run on some kind of xbox emulator that I don't know and don't want to know about...anyway, it displays the following message:

[Linked Image from mamedev.emulab.it]

That basically means that the copy protection failed*, I've investigated a little and found that it does the following:

7F20CB: BF 0A FF 89 LDA $89ff0a,X
7F20CF: 9F 38 00 70 STA $700038,X
7F20D3: DF 38 00 70 CMP $700038,X
7F20D7: F0 01 BEQ 7f20da ($1) ;if the branch is true, then the copy protection fails
7F20D9: 6B RTL
7F20DA: CA DEX
7F20DB: D0 EE BNE 7f20cb (-$12)

As you may know, $700038 is "reserved" memory, so that should return open bus / fixed value on the real HW anyway...now the question is: if they putted that kind of check, that means that is supposed to fail somehow on bootleg software, but why 0x7000xx? Some kind of Internal RAM for these copy devices (since that gets written with 0 then read back)?

*thanks to Gridle & DFJustin to translate that smile.

Last edited by Kale; 10/19/09 04:54 PM.