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2 button joystick ?

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I've removed the on-disk obfuscation from Operation Blood, but I can't find a safe place to put a button scanning routine. Since it's not really my kind of game I'm going to find something easier to do instead :)

 

Here's the deobfuscated image in case someone else is willing and able to patch it:

 

Operation Blood (deobfuscated).atr

 

The in-game trigger check routine starts at $F3F5 (in shadow RAM) and is at byte offset $C205 in the .atr file. The main load is in two parts: a big read to $4400-$FFFF from sectors $025-$19C (this is the one that was scrambled on disk) and a smaller one to $0700-$337F from sectors $1ED-$245. The loading routine for the latter is at $569A.

 

There's more loading before the game starts, including a read to $4800-$5699 from $2D1-$2EE, again using the loading routine at $569A. I haven't played far enough to know which other parts of memory are overwritten.

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7 hours ago, Eyvind Bernhardsen said:

I've removed the on-disk obfuscation from Operation Blood, but I can't find a safe place to put a button scanning routine. Since it's not really my kind of game I'm going to find something easier to do instead :)

 

Here's the deobfuscated image in case someone else is willing and able to patch it:

 

Operation Blood (deobfuscated).atr 130.02 kB · 2 downloads

 

The in-game trigger check routine starts at $F3F5 (in shadow RAM) and is at byte offset $C205 in the .atr file. The main load is in two parts: a big read to $4400-$FFFF from sectors $025-$19C (this is the one that was scrambled on disk) and a smaller one to $0700-$337F from sectors $1ED-$245. The loading routine for the latter is at $569A.

 

There's more loading before the game starts, including a read to $4800-$5699 from $2D1-$2EE, again using the loading routine at $569A. I haven't played far enough to know which other parts of memory are overwritten.

thanks for the work, although I am not very expert I found a zone that does not over write in the game $A000 at least in level 1 😅

Captura.thumb.PNG.afa24087af6d58a18ccf7bdad465c126.PNG

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20 hours ago, ascrnet said:

thanks for the work, although I am not very expert I found a zone that does not over write in the game $A000 at least in level 1 😅

 

I get a bunch of writes in A0xx on level 1 when I collect items. A000-A040 and A100-A1CF look untouched, but I can't be sure that any bytes in that area won't get overwritten on later levels. I like to see huge swaths of zeroes before I trust that a game doesn't use a block of memory for anything.

 

I'm not sure if Altirra has the option to count the number of accesses to every memory location, that'd be super handy to find out if there's anywhere that is (ideally) loaded from disk before the start of the game and (definitely) never overwritten or used for anything else. But I wouldn't be able to use it myself, because you'd have to play through the whole game and I can't even get past the first level 😅

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On 9/21/2020 at 2:26 PM, Eyvind Bernhardsen said:

I get a bunch of writes in A0xx on level 1 when I collect items. A000-A040 and A100-A1CF look untouched, but I can't be sure that any bytes in that area won't get overwritten on later levels. I like to see huge swaths of zeroes before I trust that a game doesn't use a block of memory for anything.

 

I'm not sure if Altirra has the option to count the number of accesses to every memory location, that'd be super handy to find out if there's anywhere that is (ideally) loaded from disk before the start of the game and (definitely) never overwritten or used for anything else. But I wouldn't be able to use it myself, because you'd have to play through the whole game and I can't even get past the first level 😅

Of course it's not enough to be sure, I got to level 2 and it has the same behavior.

 

I was checking $C000 and I see that they turned off the OS to add code to the game there.😅

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Anyone got an ArcadeR joystick from RetroRadionics?

https://retroradionics.co.uk/index.html#!/ArcadeR-9-pin-ATARI-standard-Joystick/p/168982750/category=0

 

I've modded mine to work with this three button mod. I will add a third button at some point, there is a spare header for the third button but for now pushing the function button to swap button 2 between fire 2 and fire 3 is good enough.

 

IMG_3918.jpeg

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On 11/4/2020 at 4:15 PM, Mr Robot said:

Anyone got an ArcadeR joystick from RetroRadionics?

https://retroradionics.co.uk/index.html#!/ArcadeR-9-pin-ATARI-standard-Joystick/p/168982750/category=0

 

I've modded mine to work with this three button mod. I will add a third button at some point, there is a spare header for the third button but for now pushing the function button to swap button 2 between fire 2 and fire 3 is good enough.

 

IMG_3918.jpeg

The ArcadeR has a solder bridge to the right of the cable.  By default it's bridged to Atari, meaning that button 2 and 3 are connected to GND when they're pressed.  If that bridge is swapped to C64, the buttons connect to VCC instead.

 

Would that mod be enough, without the need for the additional resistors?

Edited by Total Eclipse
Typo fix

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