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Hello all! First post here, so I should probably introduce myself. I am Arthur Krewat, the guy who did most of the Impossible Mission conversion from C64 code to the Atari 7800. Yes, the very one who introduced the "impossible" bug to the Atari 7800 version of the game wink

Anyway, I am in the process of fixing the bug and making a few other improvements. While doing so, I found MESS to be a great tool in debugging and actually running the code, which for the NTSC version of Impossible Mission, it's worked perfectly.

I recently found some old code of mine, and while trying to run it, it required RAM in a non-standard spot.

Is anyone doing active development or bug fixes to the Atari 7800 (a7800.c) machine?

If so, should I contact them about some improvements I think should be made, or just do it myself and submit it?

It involves an update to the .a78 file format, to add more cartridge types, so that I can define a "standard" cartridge (non-banked) but with RAM, which never really existed as far as I can tell.

In other words, I need to make RAM around $4000-$5FFF or $6000-7FFF while there is actual non-banked code in other areas. Maybe I'm missing something, but it doesn't appear to be possible with the various bits in "cartridge_type" in the .a78 file used by MESS.

While there is limited need for this modification, mostly for myself, I'd like to do this as an "official" update to the MESS Atari 7800 machine, and was wondering who should I contact about it?

While looking through Bugzilla, I see Nathan Woods has been assigned one bug, but the rest are unassigned, and no work has been done to it.

I would be happy to take a crack at fixing them, if they even still exist. I am assuming that Bugzilla is up-to-date?

Thanks all!


Atari 7800 developer, Impossible Mission, Winter Games, Summer Games, One-on-One, California Games
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Nobody is actively working on the driver, you are welcome to submit changes by e-mail to Nathan Woods (contact info) or drop by the IRC channel #messdev on EFNet. Bugzilla should be up to date to the extent that the bugs listed still exist, but if new bugs have been introduced recently they probably won't have been listed yet.

As far as modifying the cartridge format, we're currently trying to get away from custom binary formats for cartridges in favour of XML (see here) and built-in software lists in the code (see the "Fixed software lists" thread), so I'm not sure if what you're proposing would be accepted.

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Funny meeting you over here Art. smile

As was mentioned, the 7800 driver hasn't been updated in quite a while and the A78 format is in a bit of limbo as well as not being updated recently.

Interestingly there is a 7800 proto of Rescue on Fractalus that also uses RAM in the $4000 range. More info here.

Coincidentally, for reasons unrelated to MESS, I am working on a 7800 software list as well. I am nearly finished and am open to it being used in MESS if the MESS team desires.

Getting back to the A78 format, it was orginally designed for MESS by Dan Boris who also wrote the original 7800 driver. If MESS decides to eliminate the usage of the A78 format it may be worthwhile to contact Dan and update the A78 standard for use with other 7800 dev tools that still use it. The 7800 signing tool being the most important one.

Mitch

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OK, I've got something to chew on, at least.

With all the existing .a78 format cartridge binaries available, I'd hate to break the current system.

Adding the XML support might be a good way for me to get the Atari 7800 driver to support different cartridge formats.

Mitch, I also found an early dev version of my California Games that actually uses memory in the $2600-$27FF range.

So, is the intent to have MESS setup with a pre-configured list of software that determines the cartridge type? AND have a "custom" setup available through XML? Or am I misunderstanding?





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The preconfigured list would list known-good/best-available software. The custom xml can be used for unknown/homebrew/etc stuff.

At the moment, only the custom xml is officially supported. The pre-configured list stuff is still work in progress and not in any official release yet (there is still some work to be done).

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Does the pre-configured list go by checksum, title, what?


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They hold information about the software itself (things like title, year of release, publisher, mapper type) and the checksums of the roms.

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Originally Posted By Krewat
Does the pre-configured list go by checksum, title, what?


It's a database of known released (or prototype software) containing year, manufacturer, rom/disk label information, and associated checksums/hashes (CRC32 and SHA1)

The hashes are used to identify the images.

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There are some example pre-configured software lists in the current SVN.

Code:
/***************************************************************************

  Entex Industries Inc. Adventure Vision cartridges

***************************************************************************/

#include "emu.h"
#include "softlist.h"
#include "devices/cartslot.h"

#define ADVISION_ROM_LOAD( set, name, offset, length, hash )	\
SOFTWARE_START( set ) \
	ROM_REGION( 0x1000, CARTRIDGE_REGION_ROM, ROMREGION_ERASEFF ) \
	ROM_LOAD(name, offset, length, hash) \
SOFTWARE_END

ADVISION_ROM_LOAD( defender,"defender.bin", 0, 0x1000, CRC(3e280096) SHA1(33e6bc08b3e8a951942e078102e90fbc8ba729a8) )
ADVISION_ROM_LOAD( turtles, "turtles.bin",  0, 0x1000, CRC(33a23eba) SHA1(88748cf4080646e0a2f115a7f6e6001916314816) )
ADVISION_ROM_LOAD( supcobra,"supcobra.bin", 0, 0x1000, CRC(b6045c9e) SHA1(fd059081d8d82f51dd1415cc3710f1fa5ebb1336) )
ADVISION_ROM_LOAD( spcforce,"spcforce.bin", 0, 0x1000, CRC(c70d4028) SHA1(86c1a6eb8a5070f4be32bf4e83c0d5951e831d27) )

SOFTWARE_LIST_START( advision_cart )
	SOFTWARE( defender, 0, 1982, "Entex Industries Inc.", "Defender",    0, 0 )    /* 6075 */
	SOFTWARE( turtles , 0, 1982, "Entex Industries Inc.", "Turtles",     0, 0 )    /* 6076 */
	SOFTWARE( supcobra, 0, 1982, "Entex Industries Inc.", "Super Cobra", 0, 0 )    /* 6077 */
	SOFTWARE( spcforce, 0, 1982, "Entex Industries Inc.", "Space Force", 0, 0 )    /* 6078 */
SOFTWARE_LIST_END

SOFTWARE_LIST( advision_cart, "Entex Industries Adventure Vision cartridges" )


The fixed game lists make it much easier to keep track of what is dumped and also to work on corner cases. Great to see some interest in the Atari 7800 driver smile

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Originally Posted By Krewat
Mitch, I also found an early dev version of my California Games that actually uses memory in the $2600-$27FF range.


Interesting, I didn't think that area was supposed to be used because it's a shadow of the range used by the high score cart.

Mitch

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