6 replies to this topic

[vintagecloning]

I've been searching the internet trying to locate technical information about ColecoVision carts, but have come up short. I'm trying to learn as much as I can about the physical ROM chips, and have started opening up my carts.

For instance, inside the Smurf Rescue cart the PCB has two chips. I know at least one must be the ROM, but what is the other chip for? Another ROM chip? How do I tell what size in bytes does the chip(s) hold? Do I need to remove the chip from the board and use an EEPROM programmer to dump the ROM?

Here's what the chips look like. Cans somebody tell me what it all means?

------------------------
|	(c) COLECO IND	|
|	R73092   8248A	|
|	2205012		   |
|	M555885		   |
------------------------

------------------------
|	(c) COLECO IND	|
|	R73089   F8242	|
|	2205013		   |
|	F805154		   |
------------------------

[newcoleco]

Well, if usually, these eprom chips are 8 kilo-bytes each. The one at the bottom is the first one (memory map 8000-9FFF), followed generally by at last a second one (memory map A000-BFFF). Some versions of teh original Donkey Kong cartridge have 3 eprom chips, 8K each, making them 24K (24 kilo-bytes).

[vintagecloning]

newcoleco, on Wed Aug 19, 2009 8:45 PM, said:

Well, if usually, these eprom chips are 8 kilo-bytes each. The one at the bottom is the first one (memory map 8000-9FFF), followed generally by at last a second one (memory map A000-BFFF). Some versions of teh original Donkey Kong cartridge have 3 eprom chips, 8K each, making them 24K (24 kilo-bytes).

Thank you for your reply. Is there a list that shows how many eproms are in each cart, and what size they are? Also If each cart has more than one eprom in it, why are the rom images floating around a single file?

[newcoleco]

vintagecloning, on Sat Aug 22, 2009 9:04 AM, said:

newcoleco, on Wed Aug 19, 2009 8:45 PM, said:

Well, if usually, these eprom chips are 8 kilo-bytes each. The one at the bottom is the first one (memory map 8000-9FFF), followed generally by at last a second one (memory map A000-BFFF). Some versions of teh original Donkey Kong cartridge have 3 eprom chips, 8K each, making them 24K (24 kilo-bytes).

Thank you for your reply. Is there a list that shows how many eproms are in each cart, and what size they are? Also If each cart has more than one eprom in it, why are the rom images floating around a single file?

There are curiosities like some Donkey Kong cartridges have 3 eproms, and some have only 2 eproms. The reason for that is the cost of production, so they asked the programmers to optimize the game size enough to fit into 2 eproms instead of 3 and they did it. Beside that, most of the games released by Coleco are 16K, some are 24K, and that's pretty much it. A list in text that include the rom size of each game is included in a giant text file called Coleco FAQ or CVFAQ. As for getting only one rom file instead of multiple 8k rom files for each game, well it's more easier to deal with a single file.

I know for sure that one guy did replace the 3 eproms from an original ColecoVision pcb to make his own DACMAN cartridge, which is my PacMan-like game ( size 24K ). But as for the other homebrew games, they are all about 32K... and finding a 32K pcb by Coleco is almost impossible.

[vintagecloning]

newcoleco, on Sat Sep 26, 2009 11:12 AM, said:

vintagecloning, on Sat Aug 22, 2009 9:04 AM, said:

newcoleco, on Wed Aug 19, 2009 8:45 PM, said:

Well, if usually, these eprom chips are 8 kilo-bytes each. The one at the bottom is the first one (memory map 8000-9FFF), followed generally by at last a second one (memory map A000-BFFF). Some versions of teh original Donkey Kong cartridge have 3 eprom chips, 8K each, making them 24K (24 kilo-bytes).

Thank you for your reply. Is there a list that shows how many eproms are in each cart, and what size they are? Also If each cart has more than one eprom in it, why are the rom images floating around a single file?

There are curiosities like some Donkey Kong cartridges have 3 eproms, and some have only 2 eproms. The reason for that is the cost of production, so they asked the programmers to optimize the game size enough to fit into 2 eproms instead of 3 and they did it. Beside that, most of the games released by Coleco are 16K, some are 24K, and that's pretty much it. A list in text that include the rom size of each game is included in a giant text file called Coleco FAQ or CVFAQ. As for getting only one rom file instead of multiple 8k rom files for each game, well it's more easier to deal with a single file.

I know for sure that one guy did replace the 3 eproms from an original ColecoVision pcb to make his own DACMAN cartridge, which is my PacMan-like game ( size 24K ). But as for the other homebrew games, they are all about 32K... and finding a 32K pcb by Coleco is almost impossible.

I'm familiar with the ColecoVision FAQs, but I question how correct it is. It states that the cartridge Alcazar is a 32k game. However, the rom image doesn't have any data past the first 16k. I've been able to add empty space onto other coleco roms, and they ran just fine with an emulator. Does this mean the FAQs is incorrect? I haven't been able to get my hands on a cart to check it out. If the FAQs is right and it is a 32k game, does the game pcb have four 8k roms? If the CVFAQ is wrong, how does a non-expert like myself know what is what?

[Bruce Tomlin]

vintagecloning, on Sat Nov 7, 2009 4:59 PM, said:

Does this mean the FAQs is incorrect?

Probably.

And FYI, to use a ROM chip larger than 8K, you just use an AND gate to de-multiplex the chip selects.

[newcoleco]

There was attempts to update the Coleco FAQ during years, but these new versions was not supported by the same guys, and the most reccent version seems to be lost in the cyberspace. I did try myself to make my own copy up-to-date based on news about prototypes and homebrew games, but I lost interrest of doing it and my web site is gone now.