Re: [stella] Dumping ROM images

Subject: Re: [stella] Dumping ROM images
From: "Russell Babylon" <rbabylon@xxxxxxxxxxxx>
Date: Sat, 12 Mar 2005 07:24:29 -0500
I say to keep things simple.  Several years ago I made a cart reader from a
555, three 7LS161's and a 7400 NAND gate chip.  I connected this to the
parallel port of a PC and wrote some code using QBASIC, hey it was what I
had.  The 555 was set up as a one shot and was reset from one of the signal
lines from the PC port, this was how I synced the PC to the cart reader.
Using this I ws able to dump the ROMs for Sir Lancelot and Moon Sweeper.  At
the time the ROM image floating around for Moon Sweeper was only 4K, it is a
8K game and some folks were looking for Sir Lancelot.  I can't remember the
details, I will have to check my old PC to see if the program is still on
it.  It was nothing fancy but it worked.

Russ


----- Original Message ----- 
From: "Adam Wozniak" <adam@xxxxxxxxxxxxxxxx>
To: <stella@xxxxxxxxxxxxxxxxxx>
Sent: Thursday, March 10, 2005 8:39 PM
Subject: [stella] Dumping ROM images


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> 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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