Odd 7800 boards...

[PacManPlus]

Hi guys:

 

Anyone ever seen these boards before - I know Dan Boris has a lot of the different types of 7800 boards on his site, but these aren't there.

 

The left one doesn't even start up in my 7800, the middle one is a Pole Position II, and the right one was found in quite a few games.

The left one also has '24K' ROM written on it. I've never heard of a 24K game for the 7800 :-/ I don't remember which cart that was taken out of as I was gutting a lot of commons at the time.

Do any of them have any significance? I'm guessing the PPII board (The middle one) is two 16K roms.. Don't know why the one on the right is so different (jumpers)...

 

 

Anyone have any information on these?

 

Bob

 

EDIT - the '25474' one (the middle one) I found on Dan's site - don't know how I missed it

Edited April 3, 2012 by PacManPlus

[+Trebor]

Right one looks a little like a Mini-Ultra: http://www.atariage.com/forums/topic/69710-the-7800-cartridge-board-thread/page__view__findpost__p__894802

 

[jaybird3rd]

Right one looks a little like a Mini-Ultra: http://www.atariage....post__p__894802

It does look a bit like a Mini-Ultra, but the jumpers on the Mini-Ultra are SMD solder jumpers, not through-hole. It's probably just a different version of the standard 16K/32K ROM board. Perhaps I'm missing something, but looking at the jumpers on this board, I'm not quite sure what they are actually for (except maybe as a stupid way of getting around the grounding plane on the bottom).

 

The one on the left is very unusual indeed. I don't think I've ever seen a 24-pin ROM used in a 7800 cartridge. The ROM part numbers don't ring any bells, either.

[gambler172]

Hi Bob

 

I have many different boards too

greetings Walter

[+Mitch]

Yep, seen all three of them. I think the 24K one is probably Galaga, compare the number on the chips to the list: http://www.atari7800.org/museum/7800NTSCsoftwarelist.htm.

 

Mitch

[Shawn]

Yep, seen all three of them. I think the 24K one is probably Galaga, compare the number on the chips to the list: http://www.atari7800...oftwarelist.htm.

 

Mitch

 

I'm almost sure it's galaga. I've never seen that board come out of any other cart but that game. Early galaga games use that one before they switched it to a single 32k chip.

[PacManPlus]

Ah - never knew that.

[Corby]

just wondering, can 4mb boards be made?

[jaybird3rd]

just wondering, can 4mb boards be made?

Do you mean four megabits (512K)? Certainly. You can probably get 512K even with Atari's old bankswitched cartridge boards, with a few modifications. I know the C300565 has a few extra latch outputs that could be used to support larger ROMs.

[Corby]

just wondering, can 4mb boards be made?

Do you mean four megabits (512K)? Certainly. You can probably get 512K even with Atari's old bankswitched cartridge boards, with a few modifications. I know the C300565 has a few extra latch outputs that could be used to support larger ROMs.

 

oh you can! didn't know that.

 

Although I am not a programmer, is it hard to write a game that large? I'm sure it would take awhile, and i would guess abit pricey to have pcb board made up!

 

Just curious..why haven't our programmers here taken advantage of that?

 

just being nosey thats all, just some of those questions i wanted to ask!

[+Propane13]

Well, there aren't too many 7800 developers, and even writing 32K of assembly takes awhile.

People can write in C, and maybe port things, but still-- it's a dead market.

 

I guess you need to think about it terms of time investment vs .gain.

If a programmer takes 6 months to make a 32K game, completely polished, that's pretty good.

For something bigger, even if it was just map data, it could take a matter of years to write a polished game.

 

is there a bigger payout? Not really-- the market of buyers is the same.

 

So, it all comes down to how much time one of a handful of people is willing to invest in a project, when typically, other projects are in queue, begging to be looked at.

 

-John

[DracIsBack]

Do you mean four megabits (512K)? Certainly. You can probably get 512K even with Atari's old bankswitched cartridge boards, with a few modifications. I know the C300565 has a few extra latch outputs that could be used to support larger ROMs.

 

Wasn't how these were made ... by modifying COMMANDO?:

 

 

The ROM file on CC2 is 512K.

 

I thought Mitch had a prototype 512K 7800 board that Atari never used.

[Shawn]

just wondering, can 4mb boards be made?

Do you mean four megabits (512K)? Certainly. You can probably get 512K even with Atari's old bankswitched cartridge boards, with a few modifications. I know the C300565 has a few extra latch outputs that could be used to support larger ROMs.

 

Do you have further details please? I'd love to be able to use the wide variety of games as donors that are on a 565 instead of chopping up a Commando cart.

[+Propane13]

I stand corrected; I forgot that multimedia (sound / video) could easily take up that space.

 

-John

[jaybird3rd]

Do you have further details please? I'd love to be able to use the wide variety of games as donors that are on a 565 instead of chopping up a Commando cart.

I'll have to look up the details later, but it would involve running some wires to the unused inputs and outputs of the latch (the 74LS374 chip near the ROM): the inputs to the correct signals from the data bus, and the outputs to the top address lines of the new EPROM. The outputs would need pullup resistors also.

 

I've never tried it myself, but theoretically, this should replicate the bankswitching extensions that Atari added to the Commando board design, which otherwise seems to use the same bankswitching scheme as the '565. It would be a bit of work, but not much more than the usual work involved in retrofitting old Atari boards with EPROMs.