VIRUS (1988)
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as like me i garuntee you have only ever seen the game VIRUS on compilation disks the reason being is well we shall explain in this crack what you will need
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original game (find here)
an amiga or an amiga emulator (winuae)
an action replay cartridge or ar3 rom image for use with winuae
once u have all these set up we shall begin, First we need to find out what protection is on this disk ,ok so fire up your copy of XCOPY and try and make a copy of the game, hmm its not working you say? what are all these red numbers doing there they should all be green 0 …..
ah well this tells us that this is MFM protection ,which means you cant copy the tracks because of the way they are placed on the disk, ok all is not lost ,lets put the disk in and run it so reboot with the game disk inside and let it run as it loads you will notice the screen fade into many diff colours,and at the end of this colour change the game comes alive, hmm ok play the game for a while ,notice anything strange? yah thats right the game doesnt seem to load anymore from the disk, hmm ok so lets take a look at this one ,i think the game loads into ram and thats all ,no more loading from disk ,if thats the case then maybe we can grab the ram after the disk loading and save it to file ,(i.e grab the data we need without cracking the MFM) ok lets take a look at the bootsector (this cant be protected), fire up your action replay and type this
RT 0 01 050000
then type this
D 050000
ok scroll down a little bit by pressing enter ah wait whats this? a JMP so early on hmm lets take a note of this `050020 JMP 07FA04
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basicly what the code from range 050000 – 050026 does is tell the computer that once the disk is booted to put the boot code at address 07FA00 so take note of that address aswell, ok lets scroll down some more ,what we are looking for is another JMP, ah found another one do you see it at address 0501f0
ok lets take more note of this JMP that jumps to address 01000 i think we have enough information from the bootblock to move on to the next stage so restart the amiga with the game disk inside and boot up the game, after a few seconds you will notice the colour change again ok at this point hit ya action replay button, now lets goto that address the address where the bootblock gets loaded to ,remember it? it should be 07FA00 so type, D 07FA00, ah do you see the bootblockcode ,the one with the JMP ,no?
ah this is because there is no JMP now but we wasnt interested in the first jump so lets seek out the second jump scroll down some more ..see it? its at address 07FBCA and it still jumps to address 01000 so lets see what is so special about that adress type, D 01000 ah we have another jump i suspect this is the main jump that jumps into the game
so lets find out if this is the main jump into the game once the disk is finished loading, how we will do this is put a mouse wait at the address 01000, what this means is before this code is active you must press the left mouse button so type
A 1000
then type
btst #6,bfe001
bne 1000
jmp 63ec8
then press esc to get out of write mode so what this will do is the game will load and when it jumps to address 01000 it will run a new code ,the code we just wrote it will read the btst #6… part and then the bne 1000 ,,so what the bne does it tell the computer if the mouse button is not pressed (left mouse) stay at code 01000 until its pressed and once its pressed carry on to the next line of code ,which is the main jump ok once this is all done press X to leave action replay and aloow the game to continue to loadhmm its loaded we know this because the colours have stopped ,so why hasent the game started? could it be because of our mouse wait?
press the left mouse button see what happens 🙂 ah the game has started now 🙂 this is good because we can put a mouse wait at the start of the game code so before the game starts we can rip the data 🙂 so reboot wait for the colours to appear then hit your action replay again, and do the same goto address 01000 and add our mouse wait so type
A 1000
then type
btst #6,bfe001
bne 1000
jmp 63ec8
and aloow the game to load by exiting action replay, ok so the game is loaded all we need to do is pres the mouse button to start the game, but we dont want to do that insted press the action replay button ,what we want is the data from the game to be saved to disk so we know the earliest code is at addres 01000 so lets see where the rest of the data starts type nq 1000 it should start searchign memory for data and when its found data display it and the address it was found at alot of data should apear press ESC to stop it once the data starts
we will notice that the data starts to apear around the 03C000 address, so lets use this as a starting point but just to be safe start from 03A000 now we need an ending point ,we do the same but well to save trouble ill tell you its around 080000 so now we have a start address 03A000 end address 080000 jump address 063EC8 so put in a blank disk ,and lets save the data we need to that disk type sm virus,03a000 080000 this will save a file called virus from address 3a000 to 80000 ok so lets test it reboot with the data disk inside and press action replay once you have rebooted and type this LM virus,03a000 ,you should have this on your screens
ok lets test it by jumping into the address we have type G 063EC8 and press enter ,ah the game starts without the need for the original disk 🙂 ok so lets make an executable file for this data we have saved we do this using a packer program for this tutorial we shall use tetrapack 2.2 (find on any good amiga site) so fire it up and you will be aske if you want to mega crunch type N for no then you will be asked for low memory type the low address we have which is 03A000 and then you will be asked for high memory which is yup you guessed it 080000 then you will be asked for scan width lets use 200 for now
what load type do we need? select o for plain now we need a filename ,so put in the data disk and type the file name which is VIRUS load at address 03a000 wait a while for it to load the data into memory once done it will ask for any other files we dont want to add any so press enter to start the packing it will flash all strange colours but dont worry this is normal
once this is complete it will give you the crunch data which we dont really need so press enter to continue now its asking for the jump address so lets put it in 063EC0 now its asking for something called a flash register ,basicly it wants to knwo what flashing colours you want to file to display whilst decrunching select 00 as this is most common do we want a pro decrunch? no we dont so type N select a filename for the file to be saved ,lets call it virus-crackedit will ask do you want to save again? select N
and run now? select N for now the program should exit so lets test the file ourselfs, type in the name of the file which is virus-cracked and see what happens
ah all these colours apear on screen ,ok dont panic thast just the file unpacking into memory lets wait see what happens next
wooo another cracked game and also 1 filed so you can put it on a compilation disk 🙂