It is currently Sun Dec 17, 2017 10:53 am

All times are UTC - 7 hours





Post new topic Reply to topic  [ 10 posts ] 
Author Message
PostPosted: Sun Jul 24, 2005 4:09 pm 
Offline
User avatar

Joined: Fri Nov 19, 2004 7:35 pm
Posts: 3969
Are there any games out there that attempt to write to VROM?

_________________
Here come the fortune cookies! Here come the fortune cookies! They're wearing paper hats!


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jul 24, 2005 4:18 pm 
Offline

Joined: Sun Sep 19, 2004 11:12 pm
Posts: 19353
Location: NE Indiana, USA (NTSC)
Some of the later NES games may write to VROM for copy protection purposes: if a write takes, then the game must be an illegal copy. Earthbound is pretty heavily protected.


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jul 24, 2005 7:24 pm 
Offline
User avatar

Joined: Tue Jul 12, 2005 4:37 pm
Posts: 121
tepples wrote:
Some of the later NES games may write to VROM for copy protection purposes: if a write takes, then the game must be an illegal copy. Earthbound is pretty heavily protected.


I'm sorry?


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jul 24, 2005 7:28 pm 
Offline

Joined: Sun Sep 19, 2004 11:12 pm
Posts: 19353
Location: NE Indiana, USA (NTSC)
VROM content: PPU$1234 = #$A5
CPU writes PPU$1234 = #$A6
CPU reads PPU$1234
If it comes back as #$A6 then someone's obviously using VRAM instead of VROM. Authentic games have VROM; therefore someone's using a copier.


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jul 24, 2005 8:35 pm 
A really cheezy copier without a single extra latch bit and an OR gate :)


Top
  
 
 Post subject:
PostPosted: Sun Jul 24, 2005 8:46 pm 
Offline

Joined: Sun Sep 19, 2004 11:12 pm
Posts: 19353
Location: NE Indiana, USA (NTSC)
Apparently, "really cheesy copiers" were rawther common. Tetris Attack (U) for Super NES uses exactly the same technique on its PRG ROM.


Top
 Profile  
 
PostPosted: Sun Jul 24, 2005 9:00 pm 
Offline
Formerly Fx3
User avatar

Joined: Fri Nov 12, 2004 4:59 pm
Posts: 3076
Location: Brazil
Dwedit wrote:
Are there any games out there that attempt to write to VROM?


I remember of "Fantasy Zone"...

_________________
Zepper
RockNES developer


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jul 25, 2005 1:59 pm 
Offline
User avatar

Joined: Sun Jun 05, 2005 2:04 pm
Posts: 2143
Location: Minneapolis, Minnesota, United States
Karnov I think uses it, or maybe I just have an illegal copy, haha.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 26, 2005 8:47 am 
Offline
User avatar

Joined: Fri Nov 12, 2004 2:49 pm
Posts: 7319
Location: Chexbres, VD, Switzerland
tepples wrote:
Some of the later NES games may write to VROM for copy protection purposes: if a write takes, then the game must be an illegal copy. Earthbound is pretty heavily protected.

I tried to put breakpoints with FCEUXD to see that, but I saw nothing, for both the japaneese version and the american prototype. That would be stupid anyway, causing bus conflicts and an illegal copy can only use VROM due to how the game's graphics are organized, and even with a lot of romhacking stuff, the hacker could also discard this piece of code. (that would be a little less stupid with NROM games, because there is no CHR bankswitching, so they can run as well with VRAM).

_________________
Life is complex: it has both real and imaginary components.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 26, 2005 9:41 am 
Offline
Formerly Fx3
User avatar

Joined: Fri Nov 12, 2004 4:59 pm
Posts: 3076
Location: Brazil
Well, try Fantasy Zone then... If you don't avoid writes to PPU 0-1FFFh, the background doesn't appears (blank).

_________________
Zepper
RockNES developer


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: krzysiobal and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group