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Discussing the Open Source FPGA Amiga Project
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 Post subject: ActionReplay & other monitors
PostPosted: Wed Apr 10, 2013 2:53 pm 
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Joined: Tue Nov 09, 2010 3:10 pm
Posts: 316
I've been trying to fix ActionReplay on TG68 based minimigs, no luck so far. After reading how the AR is supposed to work, it seemed that disabling the fast RAM (and the autoconfig) would do the trick, but it doesn't help. BTW, does anybody know if ActionReplay ever worked on TG68 - the old one? Fixing this will definitely require more work (if at all possible).

In the meantime, I took a look at why some games fail on the TG68-based minimigs. I tried some other monitors, like HRTmon and ThrillKill (I think one of them could be made ROMable, to be used instead of ActionReplay, which AFAIK only works with 68000 and KS<2.1). Anyway, I'm looking for someone with experience with either mentioned monitor, as I'm having some problems debugging (mostly cracked) games.

First of all, what is the proper way to setup the monitor - point the NMI vector to the monitor, setup traps on other IRQs, memory location watch, ...?
Second, what is the proper way to update the NMi vector - every time I try to update the NMI vector location (I think it's $7c), after exiting and entering the monitor, the memory location gets reset to some $00f8xxxx location. Can this be done at all in this way?
Third, are these monitors even usable for debugging games, or do the games simply overwrite the NMI & other vectors, thereby effectively disabling the monitor re-entry?
Oh and fourth, does anybody have any experience with WinUAE & monitors? It seems that the NMI button only works if you use the builtin debugger.

Any help would be appreciated!

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 Post subject: Re: ActionReplay & other monitors
PostPosted: Wed Apr 10, 2013 4:27 pm 
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Joined: Mon Dec 01, 2008 9:58 pm
Posts: 1568
Location: .de
At least the HRTmon should work. Its to see in a video showing FPGA Replay board AGA support.

AR3 is very tricky and depend on some CPU timings.
The real module do not work with anything "bigger" than a 7MHz 68000.
A maximum of 2MB fast-ram ($200000 - $3FFFFF) and Kickstart 2.04 (NOT 2.05 and 3.x) is possible.

In MinimigV1 is a fix used to allow higher CPU frequence and kickstart verson, but I do not know for sure how it works. The whole thing is quite complex.

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 Post subject: Re: ActionReplay & other monitors
PostPosted: Wed Apr 10, 2013 6:52 pm 
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Joined: Tue Dec 13, 2011 7:48 pm
Posts: 341
The Action Replay 3 definitely worked on the old TG68_Fast core; I've had it running on the old DE1 builds.

English Amiga Board (eab.abime.net) or a1k.org would probably be better places to find people with experience of the debuggers.

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 Post subject: Re: ActionReplay & other monitors
PostPosted: Thu Apr 18, 2013 10:47 pm 
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Joined: Tue Nov 09, 2010 3:10 pm
Posts: 316
boing4000, MMrobinsonb5: OK, thanks for the hints! I posted a question on eab, hopefully someone there will be able to point me in the right direction.

I still haven't figured out why the Actionreplay doesn't work with the TG68K core, will probably have to setup a simulation to see what the problem is. Also, I remembered I did try the AR on the old TG68 core and it did work, you were right MMrobinsonb5. Just to see that the current minimig code is working OK, I hacked together a semi-working TG68 + current minimig sources, and the AR did at least start, but due to probably some SDRAM timing errors the core froze after a few seconds (even if the AR wasn't started).

I also modified the ActionReplay module to allow INT7 NMI to occur on key press, even if the AR is not loaded, and disabled the parts that re-map the RAM and other nasty things if AR is disabled (aron signal). That allowed me to start the ThrillKill debugger and enter it with the NMI button combination, still have to try HRTmon. It would be nice if HRTmon could be loaded instead of the AR ROM, so debugging would be usable with fastRAM & CPU>68000. It seems that a lot of games overwrite the interrupt vector table, so remapping of the table with the VBR will have to be used.

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