Using an EPROM in a SuperCartridge game to play 48k sized homebrew

[phoenixdownita]

You would probably want to skip the 8K SRAM and instead use directly a 16K SRAM (Sirius and Pluto want that).

Because 16K SRAMs are more expensive I used a 32K SRAM (M5M5256 in specific) with A14 grounded and never looked back.

 

No game that requires 8K SRAM has issues with 16K SRAM so it's safe to use bigger SRAMs.

My suggestion is to use the board you are using for RAM games or for 144K games (you can put the extra 16K of ROM in U2).

 

So told pay attention to 128K RAMless games as there are 2 classes of 128K RAMless games, most of them require page6 mapped at 4000-7fff (where the RAM chip is usually mapped on those boards) but a handful don't expect anything there so they work fine either way, in the end for all 128K RAMless games it is fine to have page6 mapped at 4000-7fff (this of course excludes Commando as it has Pokey mapped there)

In the end for 128K RAMless games a 595 or 565 (don't remember which one) is a better choice as a starting PCB but check my other thread it is all in there.

[Barakandl]

I just figured out the burning problem. My gq-4x wanted pin 24 of the eprom to the burner zif pin 2, not eprom pin 2.

So i see what you are saying about the address mapping. I tried Klax and all i got was they atari splash screen. Ninja Golf boots up and played fine from the EPROM.

 

I am in good shape now. Thanks again for all the help everyone.

 

Andrew

[Barakandl]

For future searches, for a game like Alien Brigade (144KB). The Beginning 16KB of the ROM binary goes into U2 (27128). The rest 128KB of the ROM goes to U1 (27C301/27C010/27c100).

 

It is kind of a pain, but i used my GQ-4X software to highlight, copy, paste to split up the ROMs. Took scrolling through the code to get to the offsets a long while, but worked.

[phoenixdownita]

It was known if you believe it.

 

Also to split ROMs you can use HxD, it has a tool (menu Extras\File tools\Split...) that can split in equal size chunks, and another that can reassemble (menu Extras\File tools\Concatenate...).

 

What you did works the same way for page6, split into 16K, put page6 in U2, and the full 128K in U1 (this is for PCB boards that do not allow fixed page6 at 4000-7fff).

[Barakandl]

I am having trouble getting some 128KB games to work like Klax and midnight mutants. Even splitting out page 6 and putting it at U2. I tried all sorts of combinations at U2 with no success... I get the atari splash screen and then a black screen of nothingness. All the 128KB games with RAM seem to work(including plutos that needed a 62256). Ninja Golf that has no ram and a few others did work.

 

Little research shows I may want to try using the cartridge PCB C300595. I just bought a fight night from eBay to play with. I think that will have the C300595 in it.

 

HxD is a great little program. Better than using command prompt for combining binary files.

Edited March 27, 2016 by Barakandl

[phoenixdownita]

I am having trouble getting some 128KB games to work like Klax and midnight mutants. Even splitting out page 6 and putting it at U2. I tried all sorts of combinations at U2 with no success... I get the atari splash screen and then a black screen of nothingness. All the 128KB games with RAM seem to work(including plutos that needed a 62256). Ninja Golf that has no ram and a few others did work.

 

Little research shows I may want to try using the cartridge PCB C300595. I just bought a fight night from eBay to play with. I think that will have the C300595 in it.

 

HxD is a great little program. Better than using command prompt for combining binary files.

Ask CPUWIZ for some PCBs, he sent me a few when I was experimenting and it's better than guessing.

One of the PCB (can't remember which one) has no easy way to map page6 fixed in the extra chip [which is required for many 128K games].

As a quick check you can use Ikari Warriors, if the gfx of the 2 soldiers on the side is blocky [literally 2 black blocks], then you know the game is not accessing page6 correctly.

 

TowerToppler is 64K + RAM you can play it on a 128K EPROM by simply doubling it in size (back to back copies, likely it is mapped as pages 4-7 but I've never investigated further)

 

(and yes all the games that require RAM works fine with the full 16K available as already stated)

[Shawn]

Klax needs a 595 series PCB as the timing is different on it than most other 128k 7800 games which work fine on the 339 and 565 series boards. Some games that need more than 8k sram will only work correctly on a 565 as the 339 doesn't have the higher address lines routed correctly on the pcb.

 

EDIT: Sentinel also needs the 595 board for the same timing issues. I'm not sure about Midnight Mutants off hand.

[+Mitch]

Also, in case you hadn't seen it; http://home.arcor.de/estolberg/texts/7800list.txt

 

Mitch

[Barakandl]

I tried ikari warriors with the 565 cartridge board and lots of in game sprites didn't display correctly. One flight simulator game did something similar.

 

So looks like I will use the 565 board for games with ram like plutos.

 

I will mod some other carts and see what I get. Ordered some donors from eBay.

 

Thanks for the list mitch, that helps.