BackBit cartridge on the Intellivision

[8bitwidgets.com]

ah yes, no i don't have an ECS, but yes i wonder if the backbit could have additional ram somehow.  

 

Will the ECS work with a Sears Intellivision?  A local-ish retro game place has one for sale..   it hasn't moved in forever, maybe can talk them down to a better price.  I think they are asking $150..  which is probably not the worse price, but more than i'd like to spend on it.  

 

Though I don't think I have room for it unfortunately in my current setup..   buuuuuuut that gives me an idea of how i could fix that...  

 

I can verify i downloaded the latest version from the xmas carol website and it behaves the same as in the video above.  So yea i imagine the lack of extra memory is probably the issue.  

 

[mr_me]

The backbit has ram it just has to emulate the cartridge ram in its firmware, so a firmware update.  She did say that Intellicart/CC3 bank switching is supported, but I'm not sure what Intellivision games use that.  World Series Baseball uses ECS bank switching, and i don't believe that's currently supported.  I think there's a hacked version of World Series that was converted to Intellicart bank switching.  I would expect the ECS to work with a Sears Intellivision, don't know for sure, don't think it's worth getting just for this.

Edited August 13, 2022 by mr_me

[+DZ-Jay]

1 hour ago, mr_me said:

The backbit has ram it just has to emulate the cartridge ram in its firmware, so a firmware update.  She did say that Intellicart/CC3 bank switching is supported, but I'm not sure what Intellivision games use that.  World Series Baseball uses ECS bank switching, and i don't believe that's currently supported.  I think there's a hacked version of World Series that was converted to Intellicart bank switching.  I would expect the ECS to work with a Sears Intellivision, don't know for sure, don't think it's worth getting just for this.
 

 

 

Christmas Carol does not use Cartridge RAM — not the ROM distribution, at least.

 

It is set up by the cart-mac initializer, but the game does not leverage it at all.  (This was a self-imposed limitation to not rely on it.)

 

The board release version was made for the JLP, and uses cartridge RAM as a buffer for Flash RAM.  The game stores a set of flags in RAM to unlock some Easter Eggs after you complete the game the first time.  That way, the special features are available always after that.

 

I think the problem may also be in the liberal way in which the ROM segments were divided.  I know that there have been subtle changes to the available memory map since then, to account for STIC shadow registers and things like that, but for better or worse, Christmas Carol is a bit cavalier with those boundaries.

 

   dZ.

[mr_me]

DZ-Jay is right of course, the game doesn't use cartridge ram.  The rom file configuration has a ram allocation that I don't think is used.  I'd delete the memattr section from the cfg file, run it through bin2rom, and try the new rom file in the backbit.

Edited August 13, 2022 by mr_me

[8bitwidgets.com]

Cool let me know if there is anything I can do / try to test something different to see if we can get it to work.  I'd really like to play CC on a real system! 

 

I'm talking with Eive casually over on her website about this.  However, I'm easily over my head in talking about what we need to change with backbit (if anything) to insure it has the most compatibility with the majority of homebrew games. 

 

JLP doesn't sound likely to happen with backbit so maybe that's a non starter and without JLP, the other features won't help, but it sounds like there are some other things that could be done with the backbit to expand its compatibility with homebrews without JLP.  If i'm still tracking at all.  

[+DZ-Jay]

50 minutes ago, Caleb Garner said:

Cool let me know if there is anything I can do / try to test something different to see if we can get it to work.  I'd really like to play CC on a real system! 

 

I'm talking with Eive casually over on her website about this.  However, I'm easily over my head in talking about what we need to change with backbit (if anything) to insure it has the most compatibility with the majority of homebrew games. 

 

JLP doesn't sound likely to happen with backbit so maybe that's a non starter and without JLP, the other features won't help, but it sounds like there are some other things that could be done with the backbit to expand its compatibility with homebrews without JLP.  If i'm still tracking at all.  

As a stated, JLP is not needed for Christmas Carol.  It does use unusual memory allocations (it is 10 years old, and built entirely in assembly language), and at least some type of bank-switching to swap out the ECS EXEC ROM.

 

I have a Backbit myself, so I can try playing with it to see if I can find out something.

 

If not, I could try to make a new build of the game that works with it?

 

    dZ.

[mr_me]

The cartridge version of Christmas Carol might use ECS bank switching but the rom file version does not use any bank switching at all.  Try the suggestion I posted above.

 

"I'd delete the memattr section from the cfg file, run it through bin2rom, and try the new rom file in the backbit."

[+DZ-Jay]

1 hour ago, mr_me said:

The cartridge version of Christmas Carol might use ECS bank switching but the rom file version does not use any bank switching at all.  Try the suggestion I posted above.

 

They both do -- it's the same code.  The only part that is conditional is the easter eggs code, which use JLP.  The JLP features are disabled (not assembled into the object code) in the ROM version.  The assembly code I posted above is common to both.

 

I do not know if that is ECS or Intellicart bank-switching, or whatever; but it is done in both version; and it was done so that the game worked with the ECS attached -- which it obviously does, even though there is game code at the same locations shared by the ECS EXEC.

 

Now, it could be that this is not causing the problem reported.  *shrug*

 

     -dZ.

 

[mr_me]

Try the attached file in a backbit cartridge.  Make sure there's no ECS computer adaptor.  Attached file based on the files found at www.carolvsghost.com .

Christmas_Carol.rom

[8bitwidgets.com]

Same results with that rom.  

[+DZ-Jay]

On 8/13/2022 at 9:54 AM, Caleb Garner said:

here is a video (unlisted, not for the public) I made showing what happens. 

 

Bank switching is probably the issue as i don't think this is supported yet, but hopefully i'll get word on when / if this is happening soon. 

 

 

 

I just watched the video and I find the behaviour very strange.  There is definitely something going on.

 

A few observations:

• During the title screen, those solid blocks you see, are supposed to be the serifs of the letters.  They are loaded in GRAM and rendered using MOBs.
• I see in the original code that they are loaded from ROM located at $C040 (ROM Segment #2).
• Pressing the "Clear" button from the Title Screen should take you to the "Practice" menu.
• Pressing the "Enter" button should start the game.

I do not know if any of the above is significant, though.

 

I haven't had a chance to play with my Backbit myself, but I'll see if I can get some time this week.

 

   -dZ.

[mr_me]

22 hours ago, DZ-Jay said:

 

They both do -- it's the same code.  The only part that is conditional is the easter eggs code, which use JLP.  The JLP features are disabled (not assembled into the object code) in the ROM version.  The assembly code I posted above is common to both.

 

I do not know if that is ECS or Intellicart bank-switching, or whatever; but it is done in both version; and it was done so that the game worked with the ECS attached -- which it obviously does, even though there is game code at the same locations shared by the ECS EXEC.

 

Now, it could be that this is not causing the problem reported.  *shrug*

 

     -dZ.

 

It runs fine with very old emulators, so there shouldn't be any JLP code causing problems.  It runs fine with the old dos emulator that came with Intellivision Lives CD from the 90s.  It only fails if the ECS is activated because the memory map conflicts with ecs rom.

 

That assembly code is definitely ECS style bankswitching with the $xA5F values being written to the last address in the range.  The cartridge needs that to be compatible with an ECS.  Otherwise, it looks like all the rom is mapped to valid memory ranges, not really needing bankswitching if no ECS is present. The cfg file doesn't indicate any type of bank switching, yet the program is still activating a bank.  Specifically it's calling bank F but there's no bank F configured in the rom file.  That could be a problem, I'm not sure.  Doesn't seem to be a problem with emulators.

 

15 minutes ago, DZ-Jay said:

 

I just watched the video and I find the behaviour very strange.  There is definitely something going on.

 

A few observations:

• During the title screen, those solid blocks you see, are supposed to be the serifs of the letters.  They are loaded in GRAM and rendered using MOBs.
• I see in the original code that they are loaded from ROM located at $C040 (ROM Segment #2).
• Pressing the "Clear" button from the Title Screen should take you to the "Practice" menu.
• Pressing the "Enter" button should start the game.

I do not know if any of the above is significant, though.

 

I haven't had a chance to play with my Backbit myself, but I'll see if I can get some time this week.

 

   -dZ.

There's a Stick sensitive area at $C000 - $C03F., but that's probably why your're loading from $C040.

[+DZ-Jay]

16 minutes ago, mr_me said:

It runs fine with very old emulators, so there shouldn't be any JLP code causing problems.  It runs fine with the old dos emulator that came with Intellivision Lives CD from the 90s.  It only fails if the ECS is activated because the memory map conflicts with ecs rom.

 

 

I already said there is not JLP code in the ROM version.

 

16 minutes ago, mr_me said:

There's a Stick sensitive area at $C000 - $C03F., but that's probably why your're loading from $C040.

 

The STIC areas are avoided on purpose.

 

   dZ.

[+DZ-Jay]

@Caleb Garner,

 

My recommendation is to contact @evietron directly and ask for assistance.  If technical details about the game are needed, or if a new build is required, I'd be willing to help in any way I can.  But I do not think that random people throwing spaghetti at the wall here will be of much value.

 

     -dZ.

[8bitwidgets.com]

@evietron has been contacted, but i'm in over my head on asking exactly what is needed.  Hopefully she's still following this thread and a meeting of the minds.

 

I will test more homebrews to see what's going on.  I need to purge my SD card of any non .rom files to insure i'm not trying to test games and run into issues with games that are the format not the file.  

 

 

[+DZ-Jay]

7 hours ago, Caleb Garner said:

@evietron has been contacted, but i'm in over my head on asking exactly what is needed.  Hopefully she's still following this thread and a meeting of the minds.

 

 

I would just say that a particular home-brew is having problems, and provide the ROM file.

 

    dZ.

[8bitwidgets.com]

OK I'll test more games and see if there is a common theme with any of them.  seems the backbit supports .int and .rom files.  I purged all the other roms I had on my sd card to streamline testing. 

[+DZ-Jay]

1 minute ago, Caleb Garner said:

OK I'll test more games and see if there is a common theme with any of them.  seems the backbit supports .int and .rom files.  I purged all the other roms I had on my sd card to streamline testing. 

 

I saw on the Backbit page that it supports ROM and BIN format.

 

    -dZ.

[8bitwidgets.com]

hmm i'll have to look closer..  i played lock n' chase and i was pretty sure that was a .int     i'll confirm.   i did have issues with bin games running..  but they i think were homebrews so dunno of that is part of it.  i'll gather data and put together a case for @evietron

[+DZ-Jay]

2 minutes ago, Caleb Garner said:

hmm i'll have to look closer..  i played lock n' chase and i was pretty sure that was a .int     i'll confirm.   i did have issues with bin games running..  but they i think were homebrews so dunno of that is part of it.  i'll gather data and put together a case for @evietron

 

I think ".int" files are ".rom" in disguise.  As for "BIN" files, it may be that the Backbit automatically maps the memory map of the original games, but does not support any custom CFG files.  I don't know.

 

Again, this may be something to ask in the Backbit forum.  I haven't signed up for the forum yet, so I do not know how lively and timely it is to get answers on it.

 

      -dZ.

Edited August 15, 2022 by DZ-Jay

[8bitwidgets.com]

yea .int appear to work.  though i had some have issues a number of classics i have played fine in .int format

[mr_me]

The .int files are the same as .bin and different than .rom formats.  The .int and .bin files will work as long as they use the basic Mattel memory map, as the Backbit doesn't read .cfg files for the cartridge memory map.  Those that use different memory maps should be converted to intellicart .rom using bin2rom.  You can test an Atlantis bin/int+cfg to see if reads cfg files.

 

If cartridge ram gets implemented you can test with USCF Chess to see if it works.

Edited August 15, 2022 by mr_me

[8bitwidgets.com]

3 hours ago, mr_me said:

If cartridge ram gets implemented you can test with USCF Chess to see if it works

Yea i was very curious to see if that will works for that reason.. i knew the chess game had extra ram included in it.  

 

I know that I've been having trouble getting Atlantis to play.  I've not had time to sit down and really pick at them..  but knowing that .bin will work that gives more more titles to work with and see. 

I want to approach it with a list of games not working to see if we can identify larger common issues vs. treating each game like a unique problem which could be a bigger time sink for the developer.  

[mr_me]

Atlantis, Beauty & the Beast, Microsurgeon, Demon Attack, Defender, Pacman, Centipede, Dig Dug, Congo Bongo, Championship Tennis, and most of the INTV Corp cartridges use non-standard memory maps.  They all should work once converted to intellicart .rom.

Edited August 15, 2022 by mr_me

[8bitwidgets.com]

yep some of those games failed to load.  i didn't try all of them, but none of the ones in my list you mentioned that i did try loaded. 

 

is there a tutorial on how to run the bin2rom program to do conversions?  i've never done it before and it looks like i have a LOT of things to convert