RE: [stella] Dumping ROM images

Subject: RE: [stella] Dumping ROM images
From: "Lee Fastenau" <stella@xxxxxxxxxxxxxxx>
Date: Fri, 11 Mar 2005 09:36:57 -0500
> I briefly experiminted with this sort of thing. Although I was trying to
> dump the binary using sound, which was dumb because I could never get the
> sound timing right and it certainly wouldn't fit in 128 bytes of RAM.
> Brief summary: It could work, but sometimes the RAM program would loose
> control when a cartridge was removed or inserted. And I was afraid there
> might be a slight chance of damaging the cartridge if the connection to +5
> V
> were established before the connection to ground was established. (As was
> mentioned in one of the replies to my original post).
> Dusty

I wonder if certain console models are more prone to these problems than
others.  I didn't experience weirdness on my four-switcher with the small
test program I wrote... but then I wouldn't consider those tests to be at
all scientific.

The +5 volt thing is a bit scary.  Depending on where that pin is, maybe
inserting a cart slightly crooked would help... Just to ensure ground
connects first.

I'll keep playing with it.  (I won't mind too much if I zap a cart or two.)
There's also potential for this type of code to be used for creating game
cheats...  But the execution code would have to be microscopic, probably
something like:

checkRom		lda someRomAddress	; Poll some non-zero value
in ROM
			beq checkRom		; If zero, loop
			jmp romEntryPoint		; Else, jump into

But I'm not sure what affect accessing a ROM address will have when there's
no cartridge present.  


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