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The Official "Super Expansion Module" Thread


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I've been playing ColecoVision since I first got one when I was 10. I remember reading about the Super Game Module back then, and the gameplay possibilities it promised. After the crash in 1984, I never really thought about it again until recently when I read about Opcode's new SGM. Maybe this has been addressed before, but I have a couple of questions:

 

-What were the specs of the original SGM? While I remember reading about it 30 years ago, I don't remember specifically how it enhanced the CV's capabilities. I'm very curious to know if Eduardo's SGM closely mirrors what would have been available in the CV's day.

 

-The Donkey Kong Arcade port for the SGM looks incredible. Could a port as close as that been possible on a stock ColecoVision if cartridge memory weren't an issue? I know that most ROM's in that era were 16 to 32K. If 1MB (or so) was feasible, how much better was the CV actually capable of?

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-What were the specs of the original SGM? While I remember reading about it 30 years ago, I don't remember specifically how it enhanced the CV's capabilities. I'm very curious to know if Eduardo's SGM closely mirrors what would have been available in the CV's day.

 

No, it doesn't really follow the specs of the original SGM. Today's SGM simply adds extra RAM and an extra sound chip (which effectively doubles the number of sound channels on the CV). The SGM from 1982 was pretty much a waffer drive, although I think it offered extra RAM as well. Not sure if it was supposed to have any other special features.

 

-The Donkey Kong Arcade port for the SGM looks incredible. Could a port as close as that been possible on a stock ColecoVision if cartridge memory weren't an issue? I know that most ROM's in that era were 16 to 32K. If 1MB (or so) was feasible, how much better was the CV actually capable of?

 

You have to keep in mind that RAM and ROM are two different things. The ColecoVision has a limit of 32K for the cartridge ROM, and the only way to bypass that limit is to implement some kind of bankswitching system inside the cartridge. But even if bankswitching options had been available back then, bigger ROM chips were very expensive. 128K ROMs? Forget it. 64K ROMs? Even that was unaffordable back in 1982/83/84.

 

As for RAM, the CV only has 1K of it. You can add more via the expansion port (which is what Opcode's SGM does) but back then RAM was also very expensive, which essentially explains why Coleco only put 1K of RAM in the console even though the architecture could have easely accomodated 8K.

 

Today, with ROM bankswitching and extra RAM, you can theoritically have a game like this running on the ColecoVision:

 

http://www.youtube.com/watch?v=P5vFNVlQeJM

 

(Technically, the example above is a bad one because the music and sound effects wouldn't be quite as good. But graphics and levels would be the exact same.)

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I always like to show Gradius 2 and Gofer no Yabou Episode II as good examples of what the Texas VDP can do.

 

http://www.youtube.com/watch?v=yswWoP4doI8

 

http://www.youtube.com/watch?v=Nl8p49kbOrc&feature=relmfu

 

And of course Penguin Adventure, which the NES cannot do without a good mapper.

 

All those games can run on a CV with SGM except for the sound on both Gradius 2 and Gofer no Yabou, which use Konami's custom sound chip.

 

http://www.youtube.com/watch?v=vq5_c2UCQdM

Edited by opcode
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Other MSX game I like to show is Space Manbow. Technically it is a MSX2 game using the V9958, however it uses Graphics 3, which is exactly the same as mode Graphics 2 used on almost every CV game (same limitation of 2 colors per tile line/16 colors on screen), except it offers a programmable color palette (from 512 colors), hardware scroll and 8 sprites in the same scanline. Just to show what a difference those "simple" features make.

 

Edited by opcode
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Thanks for the info. I didn't know that the CV's carts were limited to 32K by the machine - I figured that bigger ROM chips were not produced simply due to the prohibitive price that they would have cost back then.

CV carts weren't limited to 32K by the machine, per say, they were limited to 32K max due to the Cartridge PCB that was used by all the developers of CV games back in the day. If the CV had continued to be supported, eventually Bank-Switching capable Cartridge PCBs would have been developed that would have allowed for larger games to be developed. Seeing as Coleco and other companies set such unrealistic time frames for games to be completed, it might have been a while before Bank Switching technology in carts was fully taken advantage of.

 

It actually took until Opcode's release of Pac-Man Collection to witness firsthand what a cartridge that supports bank switching via the MegaCart PCB can offer and then this was followed up by CollectorVision's release of Mario Bros.

 

So while the SGM is going to open up even greater possibilities for CV game development with it's additional RAM and Sound Chip, further games that take advantage of the MegaCart Bank Switching PCB is what will really make all our CV's purr especially when used in conjunction with the SGM.

Edited by NIAD
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I've been playing ColecoVision since I first got one when I was 10. I remember reading about the Super Game Module back then, and the gameplay possibilities it promised. After the crash in 1984, I never really thought about it again until recently when I read about Opcode's new SGM. Maybe this has been addressed before, but I have a couple of questions:

 

-What were the specs of the original SGM? While I remember reading about it 30 years ago, I don't remember specifically how it enhanced the CV's capabilities. I'm very curious to know if Eduardo's SGM closely mirrors what would have been available in the CV's day.

 

-The Donkey Kong Arcade port for the SGM looks incredible. Could a port as close as that been possible on a stock ColecoVision if cartridge memory weren't an issue? I know that most ROM's in that era were 16 to 32K. If 1MB (or so) was feasible, how much better was the CV actually capable of?

 

The original SGM had a kind of tape drive and 32KB of RAM. That has been documented by several articles from the time. We no longer need the tape drive those days, as price of EPROMs are now pretty low.

The SGM doesn't change any of the graphic capabilities of the ColecoVision, so most of the stuff is still possible. In some cases creating the same animations with just 1KB of RAM can be near impossible though. In DKA's case, it runs the arcade code to make sure the game plays the same, so we could surely have a better DK than the pack-in game with less RAM, but not as accurate as DKA.

And talking about DK pack-in, don't forget to subscribe to the Opcode Club so we can read our exclusive interview with Zach Smith about DK, CV BIOS and more. Send your request to club@opcodegames.com, with name, address and age.

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Speaking of which...any news on when the Club and newsletter will get going?

 

 

And talking about DK pack-in, don't forget to subscribe to the Opcode Club so we can read our exclusive interview with Zach Smith about DK, CV BIOS and more. Send your request to club@opcodegames.com, with name, address and age.

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CV carts weren't limited to 32K by the machine, per say, they were limited to 32K max due to the Cartridge PCB that was used by all the developers of CV games back in the day.

 

Not quite correct. The addressing system in the CV's architecture is designed in such a way that the BIOS, expansion addresses, 1K of RAM and cartridge ROM are all grouped into a single addressing range of 64K. The cart ROM occupies the second half of this adressing range, so technically, the machine itself is indeed limiting the cart ROM size to 32K. That's why bankswitching is the only available method to circumvent this limitation.

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Speaking of which...any news on when the Club and newsletter will get going?

 

Greg Off is working on that. In fact I need to check with him how far along he is. We are only missing the magazine actually to start the club. The worse part is to get a template for the magazine layout done. Once that is done, we should be able to design future issues much more quickly.

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