64 replies to this topic

[labrat]

MrFish, on Tue Jun 12, 2012 1:09 PM, said:

I can't see inside much. The cart would have to be disassembled. I'd hate to ruin the label, especially since it's in such good shape. Curiosity may get the better of me though...

Some carts are just held together w/ friction pins (I doubt that's what they are actually called). At any rate, the two halves just fit snugly. Try prying apart at the PCB end at the corners versus in the middle, and it may be obvious if there is a central screw under that label. If not, the two halves may slide apart.

[MrFish]

labrat, on Tue Jun 12, 2012 1:42 PM, said:

MrFish, on Tue Jun 12, 2012 1:09 PM, said:

I can't see inside much. The cart would have to be disassembled. I'd hate to ruin the label, especially since it's in such good shape. Curiosity may get the better of me though...

Some carts are just held together w/ friction pins (I doubt that's what they are actually called). At any rate, the two halves just fit snugly. Try prying apart at the PCB end at the corners versus in the middle, and it may be obvious if there is a central screw under that label. If not, the two halves may slide apart.

I tried what you suggested and it actually does come open part way on the PCB end. It seems like there's a screw in the center though, and I can feel the depression for it under the label.

I can see inside a little, but only enough to see that there are two chips that look to be socketed.

[MrFish]

I was able to get the shell open. It wasn't as difficult to remove the label as I thought it might be, with the help of a hair-dryer and some careful prying. The shell still wouldn't come all the way open, as the two pins at the back are locked. So, I had to pry it open as much as I could, without breaking it, and pull the ROM/PCB out through the opening.

Nothing really interesting inside, other than the ROM being the UV erasable type. It is an 8K ROM chip. Maybe sending the ROM dump and the information obtained about what the code does to Bill Hogue would help him remember what it's purpose was (or just give him a link to this thread). Mimo?

I removed the ROM to clean the contacts and make sure it's well seated -- to see if it had any effect on it's functioning or the output of a dump. No difference in functioning, and the dumps were identical using a file compare.

[Bryan]

Well.. that answers the bankswitching question. There must be some custom hardware too. Did you get any 800XL's in the lot?

[MrFish]

Bryan, on Tue Jun 12, 2012 3:25 PM, said:

Well.. that answers the bankswitching question. There must be some custom hardware too. Did you get any 800XL's in the lot?

Yes I did. I can't remember if I tried the cart in that machine or not. I'm pretty sure I already opened it up to look for any upgrades. I'll take another look at it today.

[Bryan]

See if the OS ROM is stock. My hypothesis is that the cartridge is used to load a custom program (or possibly an OS image) into a modified machine. A custom OS ROM could look for the scrambled data and boot normally if it's not in RAM. If it is in RAM it could de-scramble it and use it to load a game image from disk. This could make it possible to load beta-test versions of software without ever getting a "normal" game image.

The reason for the cartridge could be that the de-scrambling code would be too big to integrate into a replacement OS or it might need to change. The fact that the data is loaded into very low memory probably means it's going to be moved into place by the next routine that accesses it. Who knows...

[MrFish]

I opened up the 800XL. I don't see anything special about it. The ROM is a standard 800XL ROM. The cartridge does nothing different in the 800XL than it did in my 130XE, including not showing any disk access at boot time. Nice clean, fully socketed 800XL though...

[orpheuswaking]

I still say wwe take the question to Bounty Bob himself..

[MrFish]

orpheuswaking, on Tue Jun 12, 2012 6:57 PM, said:

I still say wwe take the question to Bounty Bob himself..

Isn't Bounty Bob a deaf/mute?

[Godzilla]

could it be missing a chip on the left half in that picture?

[Rybags]

Such carts are pretty common - the same board can be used for 8/16K carts with the RD4 line inactive on 8K ones.

Even if it was a 16K Rom, the lower part is never accessed or called.

[orpheuswaking]

MrFish, on Tue Jun 12, 2012 7:00 PM, said:

orpheuswaking, on Tue Jun 12, 2012 6:57 PM, said:

I still say wwe take the question to Bounty Bob himself..

Isn't Bounty Bob a deaf/mute?

Yes but Bill Hogue can communicate with him

the big five website hasn't been updated since 2007... but you could try at billh@bigfivesoftware.com

[MrFish]

orpheuswaking, on Tue Jun 12, 2012 9:42 PM, said:

MrFish, on Tue Jun 12, 2012 7:00 PM, said:

orpheuswaking, on Tue Jun 12, 2012 6:57 PM, said:

I still say wwe take the question to Bounty Bob himself..

Isn't Bounty Bob a deaf/mute?

Yes but Bill Hogue can communicate with him

the big five website hasn't been updated since 2007... but you could try at billh@bigfivesoftware.com

Yea he can get BB to animate himself too.

Mimo sent him a message when I had just posted a cart pic, but maybe I'll gather some of the new information here with the other pics I've taken and send them to him to see if he has anything more to say on the subject. At this point he's about the only one capable of taking us beyond speculation.

[mimo]

I'll pm you his email later. I did link Bill to this thread but have no idea if he is interested in following it.
One thought that I had was could the cart have something to do with the porting of the 5200 version?

[MrFish]

mimo, on Wed Jun 13, 2012 12:51 AM, said:

I'll pm you his email later. I did link Bill to this thread but have no idea if he is interested in following it.

Thanks. Yea, it's not nearly as interesting as a proto or something, so he may not be following.