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Substitute for SARA RAM chip?

SARA Superchip RAM

6 replies to this topic

#1 MemberAtarian OFFLINE  

MemberAtarian

    Moonsweeper

  • 260 posts

Posted Wed Nov 14, 2018 10:28 PM

Hi guys! Until now, I really could optimize my games so they fit into 128 bytes of RAM, but with my on going strategy game I found it really impossible to fit the data of 88 tiles (at least 3 bit for one tile, so in the end, that cost 33 bytes) with all the other stuff (Population, Money, etc) and the Batari Basic variables. So I decided to use SARA for extra 128 bytes. The game would be uniqe because of the support of Amiga and ST Mouse / Trackball

This would be super, making easier to flicker the sprites those are in one row and storing the data of the building / ship that is on that tile!

 

The problem is, that we (myself and my hardware supporters :D ) couldn't find any decent and affordable solution for SARA. I mean you can buy some of the original chips (CO20231 part code) for circa 16 USD, but that would really add the final price of the actual cartridges and you can't really find SARA in a bigger ammount (or I just don't have the best connections).

 

So my question is, have you found any good substitute for SARA and a solution for adding extra RAM to the cartridge?



#2 ZackAttack OFFLINE  

ZackAttack

    Dragonstomper

  • 760 posts
  • Location:Orlando, FL US

Posted Wed Nov 14, 2018 10:45 PM

Can't you just use a melody/harmony or unocart? Either one can be flashed as a standalone cart and they both should support whichever bank scheme you want to use.



#3 MemberAtarian OFFLINE  

MemberAtarian

    Moonsweeper

  • Topic Starter
  • 260 posts

Posted Thu Nov 15, 2018 1:05 AM

Can't you just use a melody/harmony or unocart? Either one can be flashed as a standalone cart and they both should support whichever bank scheme you want to use.

I work on this project with Sebastian and I think he has a reason why he did not mention his Unocart. :)



#4 ZackAttack OFFLINE  

ZackAttack

    Dragonstomper

  • 760 posts
  • Location:Orlando, FL US

Posted Thu Nov 15, 2018 9:43 PM

Perhaps I'm missing some critical details to properly answer your question, but couldn't you just substitue any 5V parallel SRAM chip? I did a quick search on digikey and found a bunch for under $4 (USD). Sure they have much more than 128 bytes. Just limit how much of it you actually use in your implementation.



#5 Albert OFFLINE  

Albert

    Quadrunner

  • 35,184 posts

Posted Thu Nov 15, 2018 9:52 PM

How big is the game itself? 

 

 ..Al



#6 alex_79 OFFLINE  

alex_79

    Stargunner

  • 1,195 posts
  • Location:Italy

Posted Fri Nov 16, 2018 7:37 AM

Perhaps I'm missing some critical details to properly answer your question, but couldn't you just substitue any 5V parallel SRAM chip? I did a quick search on digikey and found a bunch for under $4 (USD). Sure they have much more than 128 bytes. Just limit how much of it you actually use in your implementation.

 

AFAIK the problem with using standard SRAM chips in 2600 carts is the lack of "phase 2" clock signal on the edge connector, which complicates ensuring that writes only happen when address and data lines are stabilized.

 

I don't think any working timing circuit has been developed to allow use of standard SRAM chips in homebrew games so far and, before the advent of Melody boards, the only option was to use old SARA chips (either NOS or scavenged from old games)
 


Edited by alex_79, Fri Nov 16, 2018 8:12 AM.


#7 Gemintronic OFFLINE  

Gemintronic

    Jason S. - Lead Developer & CEO

  • 9,308 posts

Posted Fri Nov 16, 2018 8:02 AM

Everyone I know who can make huge 2600 carts has said they must scavenge for SARA chips (or have me provide them).

 

I don't think you'll find a better solution than AtariAge style boards.  I think 64k ROM with SARA RAM is something that Albert doesn't need to do anything special for?


Edited by Gemintronic, Fri Nov 16, 2018 8:03 AM.





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