Fireball 2 Questions

Alrighty...

So i get my buddies S&T board and drop it in. It works great. All sounds work. Nice.

OK... I then pull the ROMS and drop them in my board... same issue.

I then pull the sound chip from his board and drop it in to mine... same issue.

I then pull the DAC from his and drop it in to mine thinking maybe I got a bad DAC... same issue.

I already know the PIA's are OK as when I swap them nothing changes...so I am now left with the CPU and that one RAM chip that his board has that mine didn't... you know... the one circled on the left in this image:

SB2.jpg


I drop that in expecting nothing...

IT WORKED! The freakin' RAM chip missing at U6 is the problem!

SOOoooo... now I get to source a RAM chip. OR maybe not... it seems my friend has one or two extra. He's giving me one when I drop off his S&T board tomorrow.

Troubleshooting is SOOOO much easier when you have a working sample to compare to.
 
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FrizzleFried said:
6802... ?!

BTW...for the hell of it I put my friends board back together but pulled the RAM chip and got the issue I got with mine.
Click to expand...

It seems like they're using the 6802 as a 6808 and using the 6810 RAM. The internal RAM of the 6802 is selectable. If the RAM enable jumper sets pin 36 of the CPU low you could install a 6802 and still require the 6810 because the internal RAM is disabled by this pin which is active high.

Jumper K should be installed and jumper L removed for 6802. If your jumpers are not set like that I would try changing them, remove the 6810 RAM and see what happens. You might not need the 6810 after all.

Another thing you could do is check for continuity to ground at pin 36 of the CPU. If it's there that tells you it's set up for 6800/6808 and you know the jumpers are opposite to what I mention above.

EDIT: For grins I looked at the memory map of the S&T in the pinmame source and the only RAM is at $0000-$007f. This is the space that the on-board RAM exists in on a 6802 (and would be external with 6800/6808). I wanted to be sure they weren't using the on-board 6802 RAM and additional RAM in the form of a 6810. I'm pretty sure my above deduction will prove to be correct. We'll see ;)
 
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I gotta go to my friends house to return his S&T anyway.... so I'll likely just get the ram, install it, and play.

:D
 
FrizzleFried said:
SB2.jpg
Click to expand...

I'm not sure if this was yours or your friend's board but in this picture I can see that jumper L is installed so you'll need the 6810 even when using the 6802 processor. You could pull this jumper, install jumper K and not need the 6810, like I said. Do whatever at this point, I already confirmed what I wanted to know :D
 
Lindsey said:
I'm not sure if this was yours or your friend's board but in this picture I can see that jumper L is installed so you'll need the 6810 even when using the 6802 processor. You could pull this jumper, install jumper K and not need the 6810, like I said. Do whatever at this point, I already confirmed what I wanted to know :D
Click to expand...


Dude...are you kidding me? You seemed SO SURE... i just pulled the L and installed the K and guess what... 1 flash and the board doesn't work.

:(
 
FrizzleFried said:
Dude...are you kidding me? You seemed SO SURE... i just pulled the L and installed the K and guess what... 1 flash and the board doesn't work.

:(
Click to expand...

wow... that's disappointing.

I assume it's working again once you put the jumpers back?

From pinrepair.com:
*1st flash*
The test program attempts to validate the condition of the 128 bytes of NMOS RAM located at page zero - address $0000 through $007F. Note that I haven't said "the test program attempts to test the RAM at U6" - why? Because Bally made an oversite with the test documentation.

If you have a 6802 installed in your S+T then the *internal* 128 bytes of RAM are tested and *not* U6 providing the 680x's RAM Enable line (pin 36) is strapped high (to the reset line) via jumper "k". The software doesn't care where the RAM is physically, as long as there is RAM at page zero (it's transparent to the software). The test program attempts to write a bit pattern to address $0000, starting with $00 and counting upto $FF. If the test program sucessfully manages to write and then read back (validate) the count, it then moves onto the next byte $0001, until all 128 bytes have been checked. 256x128 = 32,768 write cycles with validation. If this is sucessfull, the LED flashes for the *first* time (the initial flicker is not counted as a flash).

If your using a 6802 and the RAM test fails (you don't get the first flash) - you might be lucky. Move jumper "k" (the internal RAM enable jumper) to position "L" and install a 6810 RAM IC in U6 then run the test again, else, you'll need to change the 680x (the internal architecture is damaged).
Click to expand...

Maybe you have a 6802 with a bad RAM? Craziness.
 
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OK... I was a little confused.

The image above is from my friends board. He had L jumped and K not.

MY board had K jumped and L not jumped.... prior to changing it, all worked except the one sound...but if I install the RAM chip all worked. After jumping (backwards) and putting the jumper on L instead of K, I get nothing...unless I stick that RAM chip in...then it all works.

Sounds like to me:

(A) The RAM in my 6802 is either corrupt or can't handle all the sounds...

or

(B) The RAM used at U6 is used for SOME THINGS (ie the screwed up sound) regardless of whether or not you have a CPU with on-chip RAM.
 
FrizzleFried said:
The image above is from my friends board. He had L jumped and K not.
Click to expand...

Does your friend's board use a 6800 or 6808? If so then that makes sense.

FrizzleFried said:
MY board had K jumped and L not jumped....
Click to expand...

That also makes sense because yours uses a 6802.

FrizzleFried said:
prior to changing it, all worked except the one sound...but if I install the RAM chip all worked. After jumping (backwards) and putting the jumper on L instead of K, I get nothing...unless I stick that RAM chip in...then it all works.

Sounds like to me:

(A) The RAM in my 6802 is either corrupt or can't handle all the sounds...

or

(B) The RAM used at U6 is used for SOME THINGS (ie the screwed up sound) regardless of whether or not you have a CPU with on-chip RAM.
Click to expand...

I would go with A because the RAM at U6 and the internal RAM on the 6802 exist in the same space in the memory map.

Interesting that this came up though because you'll want to set the jumpers for 6800 if you're going to use a 6802 with a 6810 RAM at U6. That will disable the internal RAM. If it is in fact bad you don't want it connected in parallel with an external RAM. Unless that doesn't work in which case I don't know what I'm talking about. ;)
 
Lindsey said:
Does your friend's board use a 6800 or 6808? If so then that makes sense.



That also makes sense because yours uses a 6802.



I would go with A because the RAM at U6 and the internal RAM on the 6802 exist in the same space in the memory map.

Interesting that this came up though because you'll want to set the jumpers for 6800 if you're going to use a 6802 with a 6810 RAM at U6. That will disable the internal RAM. If it is in fact bad you don't want it connected in parallel with an external RAM. Unless that doesn't work in which case I don't know what I'm talking about. ;)
Click to expand...

I want to say his says 6806?!
 
FrizzleFried said:
I want to say his says 6806?!
Click to expand...

Probably 6808. It's all making sense now. What a round about way to find a bad RAM. haha!

My guess would be the internal RAM of the 6802 has some bad bytes causing all the problems. So you ultimately had 2 problems. Missing DAC and bad RAM. Good work fixing it. I know a lot more about S&T than I did before this thread.
 
Lindsey said:
Probably 6808. It's all making sense now. What a round about way to find a bad RAM. haha!

My guess would be the internal RAM of the 6802 has some bad bytes causing all the problems. So you ultimately had 2 problems. Missing DAC and bad RAM. Good work fixing it. I know a lot more about S&T than I did before this thread.
Click to expand...

So do I... :)

Thanks for the help...

Now to track down the two SCR's giving me problems (the lamp to the Little Demon credits and one of the playfield bonus lamps)...
 
Check the sockets *play with the bulb* to make sure its not a bad socket. If that's not it and the bulb is good I would check the ground again lol.

edit: SCR what is that abbreviated for?
 
Lindsey said:
Probably 6808. It's all making sense now. What a round about way to find a bad RAM. haha!

My guess would be the internal RAM of the 6802 has some bad bytes causing all the problems. So you ultimately had 2 problems. Missing DAC and bad RAM. Good work fixing it. I know a lot more about S&T than I did before this thread.
Click to expand...

I just double checked and it is clearly marked 6806P... mis-marking?

Regardless... I now know how to fix this bad boy.

BTW... the 6810 in my friends board actually says 68B10P or 68P10B (can't remember)... that is still a 6810, right?
 
FrizzleFried said:
I just double checked and it is clearly marked 6806P... mis-marking?

Regardless... I now know how to fix this bad boy.

BTW... the 6810 in my friends board actually says 68B10P or 68P10B (can't remember)... that is still a 6810, right?
Click to expand...

I haven't seen that part but it must function like a 6800/08/02.

Those are all 6810 RAM.
 
I am very excited getting this game up and running. I played a few games last night with the chip in place and managed to double my high score to date. Of course that all goes away tomorrow when my remote battery parts come in and I wire it up to the MPU.

Hey Lindsey... do you offer FREEPLAY ROM's for FB2? If so, shoot me over a shipped to Idaho price...
 
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