Odd 1200? cartridge

[cx2k]

In the process of dumping a bunch of carts I've picked up over the years and found this one marked "1200 SALT" but it also has something handwritten above that which I can't make out. The strange part is that the cart contains roms, not eproms. I was unable to match the co part numbers to anything (maybe my google skills are sub-par). The cart doesn't boot on an 800 or 800XL but I don't have a real 1200 at the moment to test. It also doesn't work in Altirra.

 

I even tried swapping the roms in case someone put them in the wrong spots but no luck. I dumped the cart twice, once normal and once with roms swapped. Also, didn't see any noticeable text with hex editor.

Maybe one of the experts here can delve into this a little more and figure out what it is?

 

Attached is cart pics and both rom dumps.

 

Thanks,

John

 

 

Atari 1200 unknown 8k.bin Atari 1200 unknown 8k reversed roms.bin

[TGB1718]

Does seem strange, for an 8K cart, the code looks like it's for a 16K cart, look at this snip of the disassembly

even stranger, that first JSR goes to an empty block in the ROM

 

8030   JSR  9BE7      20 E7 9B
8033   JSR  8E24      20 24 8E <<< inside the $8000-$9FFF for an 8K cart
8036   LDY  98        A4 98
8038   LDA  #00       A9 00
803A   STA  0AEB,Y    99 EB 0A
803D   JMP  A4DD      4C DD A4 <<<jmp outside the 8K
8040   LDA  #00       A9 00
8042   STA  88        85 88
8044   JMP  A5B2      4C B2 A5 <<< and again

 

and

8053   INC  DD        E6 DD
8055   BNE  8077      D0 20
8057   INC  DE        E6 DE
8059   JMP  B077      4C 77 B0 <<< and again
 

[+MrFish]

3 hours ago, cx2k said:

Also, didn't see any noticeable text with hex editor.

The texts "G A M E   O V E R", "A T T A C K   W A V E   C O M P L E T E D", and "B O N U S   X" appear in the roms. This should be recognized as from Defender by most people.

 

3 hours ago, cx2k said:

Maybe one of the experts here can delve into this a little more and figure out what it is?

Comparing with Atari's Defender cartridge, parts of the two 4K section match up. I didn't take the time to see if they were consecutive or what... but, obviously Defender is a 16K cart, so...

 

[cx2k]

1 minute ago, MrFish said:

The texts "G A M E   O V E R", "A T T A C K   W A V E   C O M P L E T E D", and "B O N U S   X" appear in the roms. This should be recognized from Defender by most people.

 

Comparing with Atari's Defender cartridge, two of the 4K section match up. I didn't take the time to see if they were consecutive or what... but, obviously Defender is a 16K cart, so...

 

Interesting. I tried dumping it as a 16k cart as well but it just showed half of it as empty.

 

[+MrFish]

8 minutes ago, MrFish said:

The texts "G A M E   O V E R", "A T T A C K   W A V E   C O M P L E T E D", and "B O N U S   X" appear in the roms. This should be recognized from Defender by most people.

 

Comparing with Atari's Defender cartridge, two of the 4K section match up. I didn't take the time to see if they were consecutive or what... but, obviously Defender is a 16K cart, so...

Actually, I should say, two large portions within each 4K section match up. I only started from the discernible text areas forward. Further analysis required...

 

[cx2k]

13 minutes ago, MrFish said:

Actually, I should say, two large portions within each 4K section match up. I only started from the discernible text areas forward. Further analysis required...

 

I still don't see the text but I'm using HxD for my editor. I took a regular Defender cart that was socketed and tried transplanting the chips into that but it still didn't work. I also tried mixing the chips to identify if one of them was bad and couldn't get it to boot. While I had it in the 16k cart I did a dump and see that it is a full 16k. No idea why it doesn't run though. Here's the 16K dump...

 

 

1200 Defender 16k.bin

[+MrFish]

18 minutes ago, cx2k said:

I still don't see the text but I'm using HxD for my editor.

 

    

 

[Ricky Spanish]

also says DEFENDER 1982 ATARI here :

0029A0   
0029B0  

Edited May 22, 2023 by Ricky Spanish
added info

[DrVenkman]

I went to go look inside my Defender cart just to verify the Atari part numbers on those ROMs but of course, as luck would have it, I can't find it. I suspect it might currently be parked under the hatch of one of my 400s or 800s in storage. 

 

But it should be easy enough for someone with the cart handy.

 

[cx2k]

10 minutes ago, DrVenkman said:

I went to go look inside my Defender cart just to verify the Atari part numbers on those ROMs but of course, as luck would have it, I can't find it. I suspect it might currently be parked under the hatch of one of my 400s or 800s in storage. 

 

But it should be easy enough for someone with the cart handy.

 

I did verify the numbers. See above. I even swapped the roms with a known good Defender cart to see if it worked.

 

[cx2k]

20 minutes ago, MrFish said:

 

    

 

Do I have a wrong setting or something??

 

[Kr0tki]

It's just a standard Defender. Your "1200 Defender 16k.bin" ROM dump, if we swap the first and second 8K blocks around, is exactly identical to the known Defender cartridge. Obviously the ROMs were swapped into incorrect sockets when you were making the dump.

 

According to the numbering present in the Atari Engineering Information System - Item Master List, parts with the code C0173xx and C0603xx are ROM #1 and #2, respectively, from the cartridges with the matching serial number RX80xx. Defender's serial is RX8025, so we have a match for both of the ROM chips.

[TGB1718]

12 minutes ago, cx2k said:

Do I have a wrong setting or something??

 

It's probably the encoding, the characters are the reverse field set i.e. bit 8 set, another way to see them

is to drag and drop the file into ATR Explorer, it displays correctly there as it's written for Atari Files and .ATR's

[+MrFish]

19 minutes ago, cx2k said:

Do I have a wrong setting or something??

You need to use an Atari font.

 

[cx2k]

21 minutes ago, Kr0tki said:

It's just a standard Defender. Your "1200 Defender 16k.bin" ROM dump, if we swap the first and second 8K blocks around, is exactly identical to the known Defender cartridge. Obviously the ROMs were swapped into incorrect sockets when you were making the dump.

 

According to the numbering present in the Atari Engineering Information System - Item Master List, parts with the code C0173xx and C0603xx are ROM #1 and #2, respectively, from the cartridges with the matching serial number RX80xx. Defender's serial is RX8025, so we have a match for both of the ROM chips.

OK. This is getting really strange. Here's a picture of a working Defender cart that I opened. Notice the part numbers and each chip is actually stamped L (Left) & R (Right).

 

 

 

 

 

Now, I reversed the other ROMS since you said the the roms were swapped and it works, but the roms weren't swapped. Here's a pic - Note that CO60325A is on the right side

 

 

Does this mean the masked roms were programmed wrong?

 

John

 

[Kr0tki]

I don't know. Notice that your production Defender chip numbers end with an A, maybe they are "revision A" chips, i.e. different? Maybe the difference is in the configuration of Chip Select lines?

 

If I understand correctly, your working assumption is that the "salt" chips are mislabelled and C017325 contains the same data as C060325A, and C060325 is the same as C017325A, right? Easy to check. If you still want to investigate, please try this: insert only one of the four chips into either socket and leave the other socket empty, and then dump the cartridge as 16K. Then post the 4 dumps.

Edited May 22, 2023 by Kr0tki

[+MrFish]

1 hour ago, cx2k said:

Do I have a wrong setting or something??

If you go into the Options dialogue and select the Format tab, you can select a font for HxD to use.

 

You need to have some modern adaptation of the Atari font installed on your system first. There are a few here: AtariWiki - Atari Truetype Fonts

 

 

[_The Doctor__]

Low and Hi are determined by the latter numbers L  R2928 8249/H  R2929 8250    , Left and Right the same L  CN52539 8245 /R  CN52540 8246

 

The chips are from different runs and may have been in different PCB's at one time. Combined Nomenclature (Cartridge Number) vs CO Number.

 

Differing sizes come into play... 40K 64K 80K 128K and so on.

Edited May 23, 2023 by _The Doctor__

[cx2k]

3 hours ago, MrFish said:

If you go into the Options dialogue and select the Format tab, you can select a font for HxD to use.

 

You need to have some modern adaptation of the Atari font installed on your system first. There are a few here: AtariWiki - Atari Truetype Fonts

 

 

Got it! Thanks!!

[cx2k]

On 5/22/2023 at 5:18 PM, Kr0tki said:

I don't know. Notice that your production Defender chip numbers end with an A, maybe they are "revision A" chips, i.e. different? Maybe the difference is in the configuration of Chip Select lines?

 

If I understand correctly, your working assumption is that the "salt" chips are mislabelled and C017325 contains the same data as C060325A, and C060325 is the same as C017325A, right? Easy to check. If you still want to investigate, please try this: insert only one of the four chips into either socket and leave the other socket empty, and then dump the cartridge as 16K. Then post the 4 dumps.

So, I did as you mentioned and you can see that they are mislabeled/programmed wrong.

 

CO17325 is same as CO60325A & CO60325 is same as CO17325A. Dumps below.

 

 

CO17325.bin CO60325A.bin CO60325.bin CO17325A.bin