Replacing Built-in basic rom with a game rom?

[Gunstar]

I just recently upgraded a couple of 1200XL's with 600/800XL OS and basic. Mainly just wanted the better OS, but I went ahead and put the basic in. But the fact is, I don't think I've used basic for anything in YEARS, and I have a basic cartridge if I do need it. But I think I remember somone putting a game rom in there instead, this is possible isn't it? Just a matter of swapping the basic chip out and putting in a game rom chip right? Or is there more to it?

[Rybags]

Possible issues:

- many 8K game ROMs are in fact on 2 x 4K chips

- some game ROMs run as "diagnostic mode" carts, they run before any system initialisation, e.g. Star Raiders. Such a ROM will run later in the initialisation process if replacing inbuilt Basic, there shouldn't be issues but it can't be ruled out totally.

- changing the PORTB value could inadvertantly swap the ROM out for RAM, another "not likely but possible" situation.

[sloopy]

Yes, i have posted a couple times with such a thing, its pretty simple, you need one of these:

http://store.go4retro.com/2364-adapter/

and one of these:

http://store.go4retro.com/products/Rotary-Hexadecimal-Switch.html

 

and then wire them together with a 512kbit mem device (EPROM/EEPROM/FLASH), and it will allow you to switch up to 7 different 8k roms in that socket.

 

this is one i put in a brown cart... the two sockets in a brown cart are the same as the single socket for the BASIC ROM...

http://www.atariage.com/forums/topic/187359-looky-what-i-uh-found/

 

someone bought the cart from me so i cant give more pics, but its pretty straight forward on how to do it, just ask and i will give step-by-step...

 

sloopy.

[Gunstar]

Thanks sloopy! I knew it could be done and was done, just forgot who and where.