[stella] Dumping ROM images

Subject: [stella] Dumping ROM images
From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx>
Date: Thu, 10 Mar 2005 23:39:28 -0500
Hash: SHA1

I got an email from someone new to the hobby, asking me how to dump ROM
images from carts.

The first method I tried was a custom piece of hardware run by a
microcontroller.  This is probably the most painful way to do this.
Connectors are hard to find (mine never fully connected; you had to hold
it and apply pressure), and you need to know lots about bankswitching.
I got mine working, but I don't recommend anyone ever do this unless
they really like programming microcontrollers and designing hardware.

The second method I tried, which I recommended to this fellow, was to
pick up an old 7800 on E-Bay and mod it out with Stolberg's DEVOS.  I did
this to my 7800 and I love it.  It does still require some soldering,
and access to an EPROM burner.  A special cable connects between the
7800's right joystick port and the parallel port on a PC.

Then I got to thinking, there might be another way to do this.

(All hypothetical from here out, so please point out problems if this
isn't possible.)

Take the same cable you use with a 7800 and DEVOS, and move it over
to the 2600.  Make a new 2600 cart.  This new cart copies a short
(less than 128 byte) chunk of code into the 2600 RAM, and jumps to it.
While we're running from RAM, we don't need to access the cart at all.
Pull it out.  Insert a cart you want to dump.  Tell the chunk of code
in RAM you're ready somehow (push the left fire button?  Game select
button?).  The chunk of code in RAM can now start reading the cart ROM
and dumping out the right joystick port.

Is this possible?  If it is, then someone like AtariAge could sell
ROM dumping kits with the RomDumper cart, the cable, and software.
No soldering required.

Unanswered questions: Will inserting and removing carts cause any noise
on the bus lines?  Can the reader code be made to fit into 128 bytes?

- -- 
adam@xxxxxxxxxxxxxxxx        http://cuddlepuddle.org/~adam
KG6GZR                       http://cuddlepuddle.org/~adam/resume.html

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