7800 Expansion Module

[doctorclu]

Glad to see this is still being worked out.

[MaDDuck]

I am really glad that this project is still a go!!

It'll be fun.

[Greg2600]

I understand the features of high scores, ram, and pokey, but how many games use a Pokey that didn't come with one? Or is this just about home brews using it? For me personally, #1 want is a flash card interface.

[Curt Vendel]

The idea is to create the ability for homebrewers who are doing more and more games to have the ability to further push the limits of their code by having a group of owners that will be able to use enhanced games that will take advantage of the extra memory and pokey and high score.

 

 

 

Curt

 

I understand the features of high scores, ram, and pokey, but how many games use a Pokey that didn't come with one? Or is this just about home brews using it? For me personally, #1 want is a flash card interface.

[Curt Vendel]

Okay, just let OpCode and Groovybee know - that I've decide just to keep the Expansion Module to a simple design:

 

High Score (with Dallas NvRAM)

16K memory

Pokey Chip

Prototype/Breadboard area

 

 

Starting the schematic tomorrow and will get it finalized in about 2 weeks and do a test board run and see how its working.

 

 

Curt

[Underball]

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

[Mord]

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

 

Since this is a passthrough module, there's nothing stopping someone from designing a flash cart to plug into the expansion module that does have flashcart/etc. I'd rather keep the price on the expansion unit itself a bit lower, especially if it helps convince more people to buy one.

[opcode]

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

 

I believe every project has a main goal. I understand where Curt is taking the 7800 expansion module, and I sympathize with that, been doing mostly the same thing with the ColecoVision/Super Game Module. Basically he is expanding some of the systems capabilities, mostly things that could be placed on cartridge but were either too expensive or a “waste” of limited resources (like Pokey chips). Now we have everything in a single package, users just need to buy it once and developers have the incentive to produce more games that use those features.

There is also the nostalgic factor of finally owning something that was supposed to have been released back in the time but wasn't. Even though the original keyboard module wasn't suppose to have exactly the features Curt is adding, I admire his integrity on keeping only features that were planned or used back then in some form. And there is also the economic factor, less features means a less expensive device, more people will buy it, more games will use it. Perfect.

[Underball]

I guess my real point was that the 7800, like most long since out of production systems, is in a phase of it's lifecycle now where preservation of original programming material is probably most important to everyone. Being able to continue the legacy of the 7800 through alternate means of preserving the original games, and any newly developed ones.

 

the High Score cart is kind of neat, sure. but all you're really preserving with that is 50 guys' individual scores on Galaga. I would think in terms of game development and system preservation, this feature would take a back seat to flash ram access to the existing and future library of game roms.

[Bill Loguidice]

Not really following you there, Underball. The existence or lack of existence of this module or inclusion or non-inclusion of any features therein has no effect either way on system or game preservation, or access to ROMs. They're completely independent processes.

[Mord]

I guess my real point was that the 7800, like most long since out of production systems, is in a phase of it's lifecycle now where preservation of original programming material is probably most important to everyone. Being able to continue the legacy of the 7800 through alternate means of preserving the original games, and any newly developed ones.

 

the High Score cart is kind of neat, sure. but all you're really preserving with that is 50 guys' individual scores on Galaga. I would think in terms of game development and system preservation, this feature would take a back seat to flash ram access to the existing and future library of game roms.

 

Where this is a passthrough type of thing, there would be nothing to stop people from designing and releasing dedicated flash cart cartridge options independently. Unlike some later systems, the emulators for the 7800 aren't that bad and are still being improved which is excellent game preservation right there. I'd rather have a separate device for roms to plug into this thing anyway. That way if one of the two busts, I still have the other.

[Curt Vendel]

Thats in the works coming from someone else already, no need to step on others toes in projects.

 

 

Curt

 

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

[Underball]

Not really following you there, Underball. The existence or lack of existence of this module or inclusion or non-inclusion of any features therein has no effect either way on system or game preservation, or access to ROMs. They're completely independent processes.

It's something that was discussed as a possible feature of this device in this thread.

 

being that the CC2 is no longer in production, and there are no current plans to make more, or other devices to replace it - this project seemed like the logical choice to give 7800 enthusiasts and archivists the ability to use ROMS on real hardware without having to hack up an existing cart to place an eprom on it.

 

Adding new hardware features to the 7800 for homebrew programmers to make future game coding more interesting, without providing a means of actually playing said finished game roms on real hardware short of hacking apart a perfectly working old cart to make frankenstein carts seems pretty limiting.

[Underball]

Thats in the works coming from someone else already, no need to step on others toes in projects.

 

 

Curt

 

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

 

I assume you mean the possibility of a 7800 Harmony cart - which, going by batari's estimate on not being able to start or even think about it until the existing 2600 harmony breaks even on sales, which is likely several years away at best, it's a nice idea that will likely never happen.

[Bakasama]

Thats in the works coming from someone else already, no need to step on others toes in projects.

 

 

Curt

 

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

 

Ah, I'm starting to see the wisdom of these devices being made separately. At least I don't have to buy a CC2 anymore.

 

Plus having a high score feature built in is big plus for me. I never did like the way High Score cart connected to the system and the game cart for aesthetic and safety reasons.

Edited April 28, 2010 by Bakasama

[jaybird3rd]

I assume you mean the possibility of a 7800 Harmony cart - which, going by batari's estimate on not being able to start or even think about it until the existing 2600 harmony breaks even on sales, which is likely several years away at best, it's a nice idea that will likely never happen.

Just be patient and wait. If there is enough demand for a 7800 flash cart to follow the CC2, someone will make it. In the meantime, there are far more surplus 7800 cartridges out there than the marketplace can absorb, so finding common donor cartridges will not be a problem anytime soon. The new 7800 cartridge boards that have been manufactured are better than any that Atari ever made, so the resulting homebrew cartridges are not "hacked together Frankenstein carts," but will last just as long as the originals have.

[HammR25]

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

I already have a CC2. I don't need to waste my money on another one just to get the features Curt's passthrough cart will give us.

[+eebuckeye]

You're going to waste nvram on getting the high score cart feature for a dead system with an audience of >1000 people max, but not add flash cart/rom loading ability?

 

Lame.

I already have a CC2. I don't need to waste my money on another one just to get the features Curt's passthrough cart will give us.

 

I want one of these!!

[nathanallan]

Me, too, and I wait patiently.

[Lendorien]

I'm curious to know how the initial tests went on the prototype, assuming you got that far.

 

The thread about the Pokey enabled Pac-man brought up a good point. It would be great to possibly bundle the expansion module with a game that uses its features to show off what the expansion hardware can do. That and an expansion module with Pokey support is a lot less wasteful than a one off cart with the pokey inside.

 

I could see once an expansion module is made, all future 7800 games would support it. Course, I have no idea how hard it would be to program a game to work without the module installed. (would need some way for the cart to look for the module). I guess you'd have to have two separate codes for Tia support and Pokey support, which would tax the space on the cart. Or you could just sell two separate carts.

 

I don't know enough about programming or 7800 hardware. But I am curious.

[opcode]

[raise hand] Well, I will be supporting it with hopefully a couple of games.

In fact I am working on one of them right now.

[TrekMD]

That is cool, Opcode.

[GroovyBee]

Course, I have no idea how hard it would be to program a game to work without the module installed. (would need some way for the cart to look for the module).

 

Provided that POKEY is located at address 0x4000, 8K of RAM is located at 0x6000 and 16K of RAM is located at 0x4000 it should work fine. The only problem will be if you want POKEY and/or 16K of RAM at the same time because their address ranges conflict.

 

Homebrew games would need a special register to write to that would control the mapping. It would either map POKEY at 0x4000 or an additional 8K of RAM at 0x4000 or maybe both. In the latter case the first 16 bytes at 0x4000 would be allocated to POKEY and then 0x4010 to 0x5FFF would be the rest of the 8K RAM.

[opcode]

Aren't there other free memory areas, like 0400h or something? Why waste RAM sharing the same range with the POKEY chip? That is what I asked Curt..

The other thing is, what happens if we try to use the module with the original Ballblazer cartridge? Or a cartridge with 48KB of ROM? I believe Curt needs a way to enable all those new features, and they must come disabled by default...

[supercat]

Why waste RAM sharing the same range with the POKEY chip? That is what I asked Curt..

 

If one were using the POKEY only for sound and were putting it on the same cartridge as the ROM, one could probably put the POKEY at address 0xE000. A pass-through cartridge might work, but the cartridge being plugged in would have to float the data bus on write cycles to ROM space. Having a pass-through device "hide" such cycles might work, or might cause problems.