Jump to content
IGNORED

Can the AtariMax be used as a means to have more Atari-8bit games working on the 5200?


Giles N

Recommended Posts

In the past, in discussions concerning which Atari-8bit(family), could be converted to run on the 5200 console, a common theme has been that the 5200 either lacks certain specs.

 

My question is: can the extra capabilities found in the AtariMax, be of use have more Atari 8bit games converted to run on the 5200 console?

Link to comment
Share on other sites

3 hours ago, Giles N said:

In the past, in discussions concerning which Atari-8bit(family), could be converted to run on the 5200 console, a common theme has been that the 5200 either lacks certain specs.

 

My question is: can the extra capabilities found in the AtariMax, be of use have more Atari 8bit games converted to run on the 5200 console?

I think I understand what you are asking..

 

The AMax carts do not add any extra memory for the 5200 to access. But it does have the ability to stream data to the console vs standard bank switching. That is how the Bad Apple and Dragon's Lair video demos work. Atariblast also uses this ability of the AMax Ultimate. These aren't normal rom files like we are used to and are more of an executable that the AMax cart understands. This file then uses an accompanying .dat file that contains the actual assets that the program uses.

 

I don't think it has been used more widely given the fact that only those with AMax Ultimate SD carts can use these files. So they aren't able to be put onto actual cartridges for the masses to enjoy and so a developer would be creating or porting the game to a smaller audience than they might want. Atariblast is the only game I'm aware of that uses this tech in the AMax cart. Everything else has just be demos/video in motion.

 

Link to comment
Share on other sites

Wouldn't it be more feasible if AtariMax offered downloadable firmware upgrades so that 8-bit files, in .xex, .car, or .rom, can also work provided they can be operated on the maximum 16K of RAM??? You would think that they would work. But also, is it possible, that certain 8-bit titles, that work within the 16K RAM, but, have more than 32K ROM, can be recoded to a .hyb file that we know the AtariMax supports also??? This can open the door for TONS of more 8-bit titles for all of US 5200 owners to enjoy as well so that we won't need to get an XEGS (like I had to last year) just to play THOSE???

Link to comment
Share on other sites

14 hours ago, BIGHMW said:

Wouldn't it be more feasible if AtariMax offered downloadable firmware upgrades so that 8-bit files, in .xex, .car, or .rom, can also work provided they can be operated on the maximum 16K of RAM??? You would think that they would work.

I wouldn't! I would think if it were feasible it would have been done by now (and as a PC app rather than embedded firmware on a SD cart).

14 hours ago, BIGHMW said:

But also, is it possible, that certain 8-bit titles, that work within the 16K RAM, but, have more than 32K ROM, can be recoded to a .hyb file that we know the AtariMax supports also??? This can open the door for TONS of more 8-bit titles for all of US 5200 owners to enjoy as well so that we won't need to get an XEGS (like I had to last year) just to play THOSE???

You don't need the .hyb format for that. @Wrathchild has been doing this for years, converting such titles as Dropzone using the bank switching scheme from M.U.L.E. which can be produced as a physical cart or run on the Atarimax Ultimate SD (it supports the M.U.L.E. format in 64K/128K/256K/512K variants). Conversions such as these are the most difficult things to do on the 5200, requiring a lot of time and dedication. It may take many years to do the conversion and get all the bugs sorted out, so I doubt he wants to do TONS of them for you.

 

As a non-programmer the only A8 games you can state as definitely possible to convert to the 5200 are those which run on a 16K 400/600XL. Configure Altirra as either of these 16K machines and see if the game works. If not then you need a programmer to analyse the game. Unfortunately such analysis is not simple, having to look at all aspects where the game may need RAM (screen buffers, character sets, P/M graphics, variables,  self modifying code etc.) which is why such questions aren't normally answered with any authority.

  • Like 1
Link to comment
Share on other sites

What the Atarimax Ultimate SD provides is:

 

(1) An interface to read data from files on the SD card into the ROM area.

 

Although I used .hyb/.dat pairs in AtariBlast! and the other demos, there is no reason why you couldn't use a .bin file and read from many different files.

 

There is one significant restriction in that you must disable the ROM before you update it. So your code must be running from 5200 RAM as must be any graphics data displayed (alternatively disable the screen).

 

(2) An interface to write data from the ROM area to files on the SD card.

 

For this to be of use you do need to use the .hyb format, since you need to be able to change what's in the ROM area.

 

Being able to read and write files on the SD card gives you the ability to store high score tables, save states and say, load/save pictures with a 5200 paint program, the sort of things you can do on an A8 with a disk drive.

 

(3) Although I don't know them, there must be interfaces for reading and traversing the directories on the SD card, since the Atarimax menu program has this functionality.

 

(4) The hybrid format which is the Atarimax's own bank switching scheme. Hybrid files must be 512K and have the .hyb file extension.

 

The cart area is split so that $4000..$7FFF is banked and $8000..$BFFF is fixed.

 

There is one range of bank switch registers which allow you to select 16K banks in the $4000..$7FFF area, standard 16K bank switching functionality.

 

There is another range of bank switch registers which allow you to select 8K banks, with $4000..$5FFF providing write access and $6000..$7FFF providing read access to that 8K bank. There are more details here:

 

https://atariage.com/forums/topic/221479-5200-ultimate-sd-cart-hybrid-8k-write8k-read-mode/

 

While this effectively provides additional RAM, it's main use is for writing data to the SD card rather than porting A8 games because of the restrictions associated with it. 

Link to comment
Share on other sites

On 10/25/2021 at 6:05 PM, baktra said:

Each candidate game would have to be adapted individually. "Market" too niche to do so in large scale.

On the other hand, new homebrews can be designed with portability to 5200 in mind from the beginning.

Ok, thanks…

 

When you say ‘each candidate game would have to be adapted individually…’ are there tools or samples of experiences that can be gathered to make to codes work on less RAM than initially intended to?

 

And if so, do we have any RAM-conversion-charts….?

Link to comment
Share on other sites

Yes there has, and as already mentioned the general conclusion is its hard work ;)

 

I have a number of games I have looked into and concluded they won't fit, e.g. Loderunner, One On One, Wargames. But then others surprise you such as Rampage & Dropzone.

 

So until you look, which involves reverse engineering the original to a state where you can identify areas of CODE, DATA, un-initialised data (BSS) and read-only data (RODATA) in order to then determine their sizes, you can't really tell.

  • Like 1
Link to comment
Share on other sites

The only real solution for making larger capacity Atari 8-bit games - and demos - realistic for conversion to the 5200 is someone building a RAM upgrade board that can plug into the ANTIC's socket. That would cut out the need for modding larger games to bankswitch on the fly like a crackhead which apparently requires way too much work for an enthusiastic homebrew programmer to do even when it is possible without slowing down the games.

 

Before his untimely passing, Curt Vendel was championing - and encouraging - this method and hoped someone else would design such a PCB since he was still trying to get the 7800 XM completed.  Such a board could also provide a socket for a PIA thus bringing SIO Port abilities to the 5200 as well [which he was a fan of since he had designed the XM to provide for such optional Atari themed capabilities* for the 7800]. Give it 512K or 1MB [or more... why stop at Ultimate 1MB capacity when Apple IIs have modern 8MB upgrades and C64 fans have 16MB REUs available]  and the only thing holding back something like a conversion of A8 Space Harrier would be a 1MB ROM cartridge design for those wanting a physical cartridge release. Throw in a socket for a 6551 and then you get serial options outside of SIO solutions.

 

 

*Curt didn't want to reverse-engineer the custom chip Atari Inc/GCC developed for the cancelled 7800 Keyboard that provided an SIO Port on said keyboard even though the keyboard itself plugged directly into the 7800's bidirectional Joystick Port #2. He felt it easier to enable SIO via PIA and POKEY on the XM board itself.

  • Like 1
Link to comment
Share on other sites

Although the information has been up for sometime, I guess I didn't soak it up.

 

Jim Leiterman wrote a "Symbolic Reverse Assembler" that he used to rip the code from GCC's version of Kangaroo for the Atari 5200 and successfully ported it over to A8 in a day. If it could convert 5200 code to work on an A8, then it should've been able to do the opposite.

 

According to his website and his interview, in the past, people have pestered him for his old code for free and he also claimed to have been under a 20-year NDA but that Infogrames later allowed him to share his archived work for free with legit historical groups. Other stuff was lost to time when he handed the stuff back to Atari Inc during the pre-Tramiel layoffs. If that Assembler truly is lost, perhaps at the right price, he could re-create it. It sounds like he still remembers the ins and outs of the A8 chipset. Although maybe others are already using similar techniques to port the software.

 

https://www.leiterman.com/atari.html

 

And here's his Antic Atari Podcast interview:

 

 

The Omni-Wheel robot toy sounded pretty cool...  and at the end of the interview, he mentions he's helped Mean Hamster Software in some ways.

Link to comment
Share on other sites

2 minutes ago, Lynxpro said:

 

Yes but it would take a number of folks committed to it to make it worth his while to design it...

Committed to buy it when released or committed to do technical stuff?

 

What do you think Leiterman would want to recreate the Assembler you mentioned?

Edited by Giles N
Link to comment
Share on other sites

If someone could donor a 5200 unit and controllers to @tmp then potentially an AVG variant could be produced. As the 5200 has no read/write line on the cart bus then this (and potentially a click signal) can maybe be brought into the cart from the extension port via a cable like the current SIO one.

 

As for code scanning to replace 5200 with A8 access and vice versa, it would only go part way, you've still got many other things to worry about. There is no magic bullet.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...