Atari 800 Rom mod question.

[BigFOX]

I got my Atari 800 at a thrift store when I was in JR High. It works perfectly, but its ROM card has some kind of after market mod on it with a toggle switch. To this day I have not been able to figure out what it does. The daughter card has no text other then Comp Side and Circuit Side.

 

Attached is a picture of the ROM card with the mod attached.

 

If anybody knows what this thing does, I would be very happy if you could tell me.

[Rybags]

Probably a second OS.

 

Try turning the machine on holding SELECT with the toggle switch in each position.

Try again with OPTION (I forget which one Omnimon originally used).

 

Might also have the fast maths ROM included - you'd probably notice most with some BASIC games running a bit quicker.

[FULS]

Hi,

I think that might be a board called "Impossible!" by Computer Software Services(CSS). It was the first back-up tool that made backing up protected programs on unmodified disk drives possible. I remember using it to backup "One on One" by EA Sports.

[BigFOX]

Well, Option, Select, and Option+Select don't seam to do anything in any switch position. So It may be that "Impossible!" thing. Sounds like it needs special software to do what it does. Oh well, at least I know what it might be.

 

Thank you both for your responses.

[FULS]

Well, Option, Select, and Option+Select don't seam to do anything in any switch position. So It may be that "Impossible!" thing. Sounds like it needs special software to do what it does. Oh well, at least I know what it might be.

 

Thank you both for your responses.

 

Hi,

Maybe this disk will help. I think your toggle switch on the Impossible board needs to be in the center position to activate it using the disk.

The other position adds 4K static ram making your 800 52K. The 3rd position disable the impossible.

Impossible.atr

[Chuck Gill]

I have one that looks just like that. It is an Impossible board. I do have the docs around here someplace, let me know if you need them I can scan them into a pdf file.

 

It does actually work to copy protected disks, but the copy can only be played on the computer with the Impossible installed and enabled

 

I was thinking about selling the 800 I have with the impossible board in it. I have several other 800's and never use it.

 

 

-Chuck

[Chuck Gill]

Documentation for "The Impossible" board.

 

-Chuck

 

Impossible.pdf

[BigFOX]

Thanks for the docs and the software. I won't be able to try it until I get an SIO2SD or something, but the documentation should answer some questions, If I can get that extra 4 K part of it working, that will be worth it just by itself.

[BigFOX]

Well, I had to replace the switch on it as it was busted under all that tape. I also cleaned up the wiring work a bit and attached the switch with double sided stinky pad to the ROM board so it looks better.

 

I haven't been able to test the "Impossible" coping part of it, however, the 4K extra memory part works fine. My 800 is sitting pretty on 52K of contiguous usable memory. However, if the Basic cartridge (and I am assuming any other cartridge but cannot test it) it is loaded after the extra 4K and it becomes invisible, but from what I have been reading elsewhere it is still usable if you know how to access it.

 

I found this information about how the memory is mapped in the 400/800 machines.

http://www.atariarchives.org/creativeatari/The_Mosaic_64K_RAM_Card.php

 

Thanks again for all the help.