Re: [stella] Gameline

Subject: Re: [stella] Gameline
From: Kevin Horton <khorton@xxxxxxxxxxx>
Date: Wed, 22 Aug 2001 18:36:02 -0500
At 08:39 PM 8/21/01 +0200, you wrote:
> >I was wondering, has anyone tried dumping/disassembling the firmware in
> >the Gameline modem?
> Already done that.

Could you please tell us how big the ROM and RAM in the Gameline is?
Also how does the bankswitching and the RAM access work? And how does
the Gameline communicate with it's internal modem?

Sure. The gameline is kinda neat inside actually. I should scan the PCB from one. It has 1 4K ROM, 4 normal 2K RAM chips, 1 2K RAM chip that is battery-backed, and a small (32 byte?) PROM which holds the unit's serial number. There's a hybrid device which I think has some DACs on it for the touch tone generation (done with the main 40 pin chip, which also handles the banking and other modem functions). Interestingly, the guy I talked to told me that you could add another 2K of RAM to the unit by utilizing an otherwise un-used pin on the 40 pin chip. I added this to mine since some of his games required it.

As for how the banking works, I haven't really looked into it too much. It uses writes to the lower half of the memory space, interestingly enough. I haven't worked on this in a very long time (3+ years) so my recollections may be off slightly.

I traced out most of the connections, but got stymied a bit by the hybrid which would be tough to RE... its only functions were phone-related though by the looks of things. As for how the modem itself works, I have no clue at all. When you load a game up, it looks identical to the Supercharger's loading screen with 2 differences- it's red instead of blue, and the tone uses a different setting on the sound channel (i.e. instead of a clear tone you get a rumbling type of tone). I listened in to it on an extension while it did its thing and it had some decent error correction going on 'cause if it picked up noise (since I had the phone off hook to listen in!) it would re-transmit a block of data. Encoding sounded like 2 tones; similar to what's used for 300 baud modems.

> Yes, I connected to a Gameline server sometime in '98 (I think it was) and
> used it to play games.  I have a VHS tape of me going through the menu and
> connecting and all that fun stuff.  Someone e-mailed me out of the blue
> saying he had this Gameline server up, and that I should give it a try...
> which I did.  He has since taken it down from what I hear.  He had it
> hooked up so the whole town could call in for free and play during the
> mid-late 80's and early 90's.

So did you get to play "Save the Whales"? ;-)

No! I asked him specifically if he had that :-) He said he bought a Gameline specifically so he could figure out how to use it, and he said he never even subscribed to the service; only using it long enough to figure out how to interface with it. He then made a compatible "server" and hacked 500 or so 2600 games to run on the damn thing, including many rare titles like the Magicard (I asked; he wouldn't sell any of it. drat!). I think I went through the complete list (or close to it) and recorded it on the tape. I need to haul that tape back out and look over it again.

To call his server, I had to do this: pick the phone up, dial his number, then turn the 2600 on and let the Gameline "call" while the other end was ringing. (Had to do this since the phone number it calls is hard-coded in) Took a couple tries to get that to work. Once it connected, it downloaded the menu program to the battery-backed 2K of RAM and played a bar of "Revelry" and brought up the screen that let one select the desired game via a number (or, let you see the menu of games). Interestingly, once connected, the Gameline "remembered" the proper phone number for when it had to call next time and I didn't have to do the special dialing procedure.

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