What kind of IC is missing from this cartridge board?

[graywest]

Hello all,

 

I recently purchased this Atari 8-bit computer cartridge "as-is" from Ebay, and I'm trying to repair it. It seems to be missing an IC.

 

Can you tell from the picture what type of IC should go into the empty slot? A little background: This is a Sirius cart of "Squish 'Em", which should be an 8kb cart. The missing IC is something with 24 pins. I assumed that it would be a ROM of some sort.

 

Also, can you tell me the purpose of the chip that is soldered to the board? Is *that* the mask ROM, and the cart is missing something like a hex inverter? I tried to look up the part number and couldn't find anything. Says "(c) Sirius" on it, which now that I think about it, makes more sense as the ROM. I mean, why would Sirius have their copyright on a standard hex inverter?

 

Thanks for the help.

 

[graywest]

I suppose it could also be that the board needs 2 4kb roms, one of which is missing. I'm not entirely sure how bankswitching works on the 8-bit computer line...

[TGB1718]

That chip is a 4K ROM, not EPROM, so no window, as @graywest says, one seems to be missing

 

Edited May 17, 2020 by TGB1718

[blacka013]

Very strange. When you examine the bottom set of solder pads, they don't appear to have been tinned ready for soldering, they appear to be bare copper. 

 

Also the solder in the through holes would appear to be from the wave soldering process.

 

[TGB1718]

5 minutes ago, blacka013 said:

Very strange. When you examine the bottom set of solder pads, they don't appear to have been tinned ready for soldering, they appear to be bare copper. 

 

Also the solder in the through holes would appear to be from the wave soldering process.

 

Yes, I noticed that really strange

[graywest]

Thanks, all. So it sounds like there is a 4kb ROM with half of the code missing.

 

What do you think is the best way to go about getting this running ? I do have the capability of erasing/writing EPROMs. Could I replace the missing ROM with a 4kb EPROM? Or do you think it's best to just trash the board and replace with an 8kb board of modern design?

[_The Doctor__]

Dump what you have, people can inspect what it is, maybe someone will match up part number from chip also... then we could see what it really is and the best way forward

[+Nezgar]

With a quick look at the .ROM dump of Squish'em! from AtariMania, I see only the 2nd half of the 8KB contains data. The first half is blank.

 

So this cart is correct for only 4KB of code.

 

According to the datasheet posted by @TGB1718 you can directly replace it with a 2532 EPROM. I have some 2532's on hand, PM me if you'd like me to program and send you one.

 

[Rybags]

There are some 4K carts out there.  Gridrunner is another.  Sometimes they're dumped as 8K because the 4K image usually mirrors in the first half.

[+Nezgar]

The educational system master cartridge is only 2KB.

 

I think theres some emulators and such that dont support 2K or 4K ROMs/CAR's well so theyll be padded to 8K for compatibility. Some could repeat, and some may truly show blank space in real hardware. Might take extra logic to do that though.

[graywest]

8 hours ago, Nezgar said:

With a quick look at the .ROM dump of Squish'em! from AtariMania, I see only the 2nd half of the 8KB contains data. The first half is blank.

 

So this cart is correct for only 4KB of code.

 

According to the datasheet posted by @TGB1718 you can directly replace it with a 2532 EPROM. I have some 2532's on hand, PM me if you'd like me to program and send you one.

 

Interesting. So what I'm gathering from all of this is that there was likely *never* another chip on the board (wave solder in the through holes, bottom row not tinned). And so the problem is possibly that the ROM (TMS2732) is bad and just needs to be replaced. PM sent.

[_The Doctor__]

sometimes a scrubbing and solder touch up is all a 'dead' cart needs....  you can't always see the card edge fingers are glazed over or solder/rom legs that aren't what they used to be.... once it's been cleaned, glazing scrubbed away and a touch up has been given they often come back to life.

Edited May 18, 2020 by _The Doctor__

[Rybags]

So is this cart complete or should it have another Rom?

And those traces... are any severed?

 

Do you have facility to transfer data from Atari to PC?  Such as SIO2PC or otherwise?

What we could do is attempt to dump it then compare against a known good Rom.

[graywest]

I just had a thought... maybe this cartridge is not broken at all.

 

I've only tested this on an 800XL. Is it possible that it requires a 400/800 OS to run?

 

I'm going to kick myself if that's the case. ?