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- Path: f411.n201!not-for-mail
- Newsgroups: comp.sys.cbm
- X-Comment-To: Chris Cochems
- From: Pontus Berg <Pontus.Berg@p71.anet.canit.se>
- Date: Thu, 04 Jan 96 23:45:58 +0100
- Subject: A Hacker's Question..
- Message-ID: <820820263@p71.f411.n201.z2.ftn>
- References: <3431487726@news.tdl.com>
- Organization: BoArDgasm, Farsta, Sweden
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-
- In a message of 03 Jan 96 Chris Cochems wrote to All:
-
- >> You make it sound as if it's all there! "... leaving you with the
- >> reset-protected program in memory, or at least the parts of the program
- >> that was not trashed by the reset".
-
- >> By a reset you can say goodbye to $0000-$07e8, $07f8-$0803, $8000/$a000
- >> (whichever is hit with $55 by the resetroutine, depending on how smart
- >> you cart is) and also $fd30-$fd50. Not seldom are these areas vital to
- >> the game!
-
- CC> Well, Fast Load does a very fast reset, so I think it doesn't trash
- CC> much of anything. It modifies two locations used in BASIC, and
- CC> switches itself out without going through most of the long
- CC> initialization routines.
-
- No no no... A fastloader does NOT normally do a reset! The might init a few
- thing they touched themselves, but they don't do a full reset. Show me one that
- does!
-
- CC> Anyway, coders can easily defeat all snapshot carts by putting code to
- CC> read the cartridge IO lines, and making sure all of them return either
- CC> zero or non-constant values. If ANY of those locations contains a
- CC> constant non-zero value, there's a cartridge in for sure. I don't
- CC> think there is a snapshot cartridge that cannot be found in this
- CC> fashion.
-
- Well, I don't do protections but The Expert can be switched out and I'm PRETTY
- sure you can't detect it this was (QED, the Expertfreak, might tell you more!).
- Action Replay has a disable mode ("Normal reset"). I'm not sure this works on it
- in this mode either! On the other hand an "LDA $DE00" will make if go bezerk
- once it IS switched in! I've seen one or two programs that complained after a
- freeze with the action replay, and I don't think your idea is uniqe enough to be
- enough all by itself!
-
- I have tried your type of solution, however implemented a bit differently:
-
- ldx #$00
- txa
- loop1 eor $de00,x
- dex
- bne loop1
-
- If this loop returns the same value say three times (in the accumulator that
- is), there is a dumb cart in the other end. (You could do a more complex one
- with $df00 check and so on as well, but if I had them both in the same loop a
- cartridge using only one of the pages would sneak by...)
-
- Now, having the drive getting regular signals from the computer and hanging the
- drive if they don't come for a second or so, is an EFFICIENT way to prevent
- freezing during play (takes a multi level game or there's really no point it
- hanging the drive). It's amazingly few crackers around who learned to code the
- drive. It's all 6502 assembler with two new timers (not to many learned the
- timers in the c64 either, comming to think of it ;), a new memorymap and a new
- rom that is well documented!
-
- CC> I have seen games (such as Ultimate Wizard) that will not load if you
- CC> have ANY cartridge in. Even with a disabled fastload, it will not
- CC> work!
-
- From disk? (Mind sending a nibbled copy for educational purposes?)
-
- CC> It's kinda too bad they put so much work into doing that, cause it's
- CC> really easy to just filecopy the disk, and add your loader code from
- CC> you old cracked copy of WIZARD to crack Ultimate WIZARD. If they had
- CC> just encrypted all the files instead, it would have been a bit tougher
- CC> to crack.
-
- CC> As it is, my cracked copy of Ultimate Wizard is compatible with Fast
- CC> Load, where the original is NOT!
-
- Neat. I always ripped out the old loader myself. Either installed an IFFL
- (level linking and fastloader) or used standard kernal to open for fastloaders -
- carts or harwarebased...
-
-
- /Pontus Berg, Bacchus@FairLight.COM
-
- ... I asked one of the guys at the booth to demonstrate me the multitasking
- abilities of his system and he replied "Please wait a few minutes sir,
- as soon as this disk formatting is completed, I will show you real
- multitasking..."
-