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Ratcatcher 5200 - Conversion?

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If anyone is interested in doing a conversion of this new, original 5200 game for the 8-bit computers, the author has provided the source code and his blessing.

 

Thread here: Ratcatcher 5200

 

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If anyone is interested in doing a conversion of this new, original 5200 game for the 8-bit computers, the author has provided the source code and his blessing.

 

Thread here: Ratcatcher 5200

 

 

Author here. Just stumbled across this thread and thought I'd add some comments.

 

The code for the game is licensed under the GPL, so my blessing isn't actually required for anyone to attempt this port, but it is given nonetheless. That being said, any port would in turn have to be GPL licensed and the source must remain open.

 

I've never actually used an Atari computer, but I learned plenty about them while researching the 5200, since most of the programming resources out there are for the 400/800. My understanding is that the computers use 2600 sticks with only one button. The game uses both 5200 buttons, so some alternate control scheme would need to be implemented. The up/down axis on the sticks is unused, so some kind of up+button thing would probably work.

 

The joystick/button routine is isolated, so dropping in a replacement should be pretty simple. Likewise, the interrupt handler for the keypad and the start/pause/reset buttons is similarly modular.

 

All of my accesses to the support chips use the symbolic register names, so changing the page mappings should be trivial. My biggest concern is that I use a lot of page 0 memory, and I think the 400/800 reserve more of page 0 than the 5200 does. Some of that data could probably be moved elsewhere without too much trouble. Some of it is used in hblank interrupts and probably needs to stay, but that will require some testing.

 

I think a port should be extremely simple for someone that knows what they're doing. I assumed someone might want to give it a go and tried to code accordingly. I will happily answer any questions about the code and help where I can,

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Oh wow, that's awesome. I would be very interested in knowing what those two bugs were.

 

thanks...

there was an error while calculating bonus stage (summary.s) above level 12 so the game crashes at level 13...

the other thing i found was, that the warning lights on the right side wont draw correctly from time to time because of a missmatch of the rightblinktimer variable (game.s, needs to be 4 successive bytes)...

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there was an error while calculating bonus stage (summary.s) above level 12 so the game crashes at level 13...

 

 

I assume you're talking about this:

    ; If the stage is a multiple of 6, it's a bonus stage.

    ; Subtract 12 until the result is less than 12.

    sec

.bonusloop

    sbc     #12

    cmp     #12  <------ Need to add this.

    bcc     .loopdone

    jmp     bonusloop

.loopdone

    ; At this point, if the number is 0 or 6, it's a bonus stage.

    cmp     #0

    beq     .startbonusstage

    cmp     #6

    bne     .startnormalstage

That's an odd one, I swear I'd played past that point before, maybe I broke it at some later point.

 

 

the other thing i found was, that the warning lights on the right side wont draw correctly from time to time because of a missmatch of the rightblinktimer variable (game.s, needs to be 4 successive bytes)...

 

 

Wow, totally right. I must have shifted the memory blocks at some point and never caught that last one.

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HI.

 

I just found that the 8bit version is missing the 3 players option. that's a pitty!! For the Atari 8bit computers there are various options to connect more than 2 joysticks (Atari 800 native, Multijoy).

 

I dont' know much about the 8bit <-> 5200 conversion of Homesoft. But what would be a good starting point to enhance the 8bit version to the originaly intended 3 player mode? The homesoft version or doing the 5200 conversion again from the original source of Average Software?

 

regards,

twh

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ok. krupkaj, fandal and homsoft are already preparing the 3 player version for multijoy. I think it will be released soon. I'm alpha testing it currently.

 

greetings,

twh

Edited by twh/f2
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ok. krupkaj, fandal and homsoft are already preparing the 3 player version for multijoy. I think it will be released soon. I'm alpha testing it currently.

 

greetings,

twh

 

I'm impressed and somewhat flattered that people are actually doing something with this code.

 

Even more surprising is that no one has asked me any questions about it yet.

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When a project arrives at an opportune time, amazing things happen in short order! Atari programmers can do almost impossible things at the right moment. And when they are on a roll you won't get many questions... but you will get some mighty fine answers!

 

Kudos team! Kudos!

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