Replacing XEGS Missile command ROM?

[tschak909]

Is the Missile Command ROM in its own ROM? Can it be replaced with e.g. an 8K EPROM? I'd like to replace Missile Command on my daughter's XEGS with a diary program I am writing for her.

 

-Thom

[+Nezgar]

Missile Command (8KB), BASIC Rev. C (8KB), and the 16KB XL/XE OS. Rev.4  (16KB) are all contained in a single 32KB mask ROM in the XEGS. (C101687) A 27c256 EPROM is a drop-in/pin-compatible replacement if you program it with the right geometry.

 

Check out this prior thread for more details. The last post has an example of a customized ROM that replaces Missile Command with Star Raiders, and replaces BASIC with Galaxian.

 

[tschak909]

oh ok. That makes perfect sense.

 

Am guessing that the ROM is soldered? (it would be just too much luck to think it's socketed)

 

-Thom

[+Nezgar]

1 minute ago, tschak909 said:

Am guessing that the ROM is soldered? (it would be just too much luck to think it's socketed) 

Unfortunately yes, it's pretty much guaranteed to be soldered to the motherboard.

[tschak909]

That's okay, I'll get somebody to desolder it and pop a socket in there.

 

I have CP, so I should be NOWHERE NEAR an iron.

 

But this is okay. My first task is to do the diary program. My work with the Mr. Robot formatter showed me I can do this in CC65 and fit comfortably in 8K... I think.

 

...I hope...

 

....

 

-Thom