(Topic ID: 340052)

Gorgar with never-ending bonus countdown

By DickHamill

7 months ago


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Topic Stats

  • 12 posts
  • 6 Pinsiders participating
  • Latest reply 7 months ago by slochar
  • No one calls this topic a favorite

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#1 7 months ago

I have Gorgar running on an original System 6 board with all new sockets, new ROMs, new 6810s, and a new 5101. Everything works except the bonus countdown after the machine has been running for a few minutes. First few games are okay, but then the bonus countdown will run forever.

Changing the 6810s and 5101 yields the exact same behavior. I'm about to try changing the processor, but I'm struggling to come up with an explanation as to why a damaged processor could run everything normally except the bonus countdown.

Anyone seen this before or have a suggestion for something to try?

#2 7 months ago

Try new ROM?

#3 7 months ago

Absolutely correct -- thanks slochar .
The problem was due to subtle bit rot of the ROM I just flashed.
Address 0x0353 is supposed to be 0x7B and it had become 0x7A on the chip.
That's it. Just one missing bit and bonus countdown was broken.

#4 7 months ago

New flash on different eproms. The bonus CD in system six has its parameters in the game ROM and the actual routine in the os roms.

#5 7 months ago

Great job. I just wish I knew what you were talking about.

#6 7 months ago
Quoted from iamdrunker:

Great job. I just wish I knew what you were talking about.

You don’t understand gibberish? Me neither!

#7 7 months ago

0x47 0x72 0x65 0x61 0x74 0x20 0x6A 0x6F 0x62 0x21

#8 7 months ago
Quoted from DumbAss:

0x47 0x72 0x65 0x61 0x74 0x20 0x6A 0x6F 0x62 0x21

Now I get it. Thank you.

#9 7 months ago

Yeah, it’s like 25 or 6 to 4 or 25 or 624

#10 7 months ago
Quoted from iamdrunker:

Great job. I just wish I knew what you were talking about.

I'm sure you're just being cheeky, but in case anyone is curious about the full explanation...

I've never seen an issue where a solid state game gets stuck in a bonus countdown, but my first guess was the RAM. I figured that there might be a RAM location where the BonusX is stored and then decremented during the countdown. Maybe that place in RAM was always reading 1 or whatever. Never getting to zero, it would get trapped in a loop.
But I replaced the RAM (6810 chips) and the battery backed-up RAM (5101) but the issue continued. Maybe it was a lack of imagination, but I didn't figure that my ROM would have gone bad so quickly. I burned and verified those chips (Flipper ROM Green1 & Green2 and Game ROM) just last week. It should have occurred to me that one of those had gone bad. I guess that the reason I didn't suspect them was because when a ROM goes bad the results are often very obvious. The game won't run at all because the CPU jumps to nowhere and hangs.

But slochar was right--the problem was with the Game ROM. As he pointed out, the code to run the bonus countdown lives in the Green Flipper ROMs, but the parameters for the countdown come from the Game ROM. Maybe the speed of the countdown, which lamps are used for 1k, 2k, etc., or what sound is played with each 1k rewarded? I'm not sure what other parameters there are.

Just to be sure, I removed each of the 3 ROMs separately and verified them with the programmer. The Green 1 & 2 checked out--they hadn't changed since I burned them. The Game ROM was 1 bit different from what I burned. It's a 2k chip (2716), so there are 16384 bits of information on there, stored as 2048 bytes (8 bits per byte). The byte at location 0x0353 (that's in hexadecimal and equals 851 in decimal) is supposed to be 0x7B (which is 123), but when I read it with my programmer, it had become 0x7A (which is 122).

So the 2716 Game ROM that I just burned had lost a single bit and that was causing the count down issue. Replacing the ROM fixed the problem and I tossed the bad chip. If you expose the 2716s to UV light through that little window, the data on them will all go to 1s. They're only set to 0s if you apply programming voltage (I think it's 28V for these?) in a particular way that burns the little fuses inside. So there was no circumstance other than a failure that could explain this change.

In the end, it was a simple explanation and very straightforward (runtime bug caused by bad firmware), but I just wasn't getting there in my logic. When my ROMs have gone bad in the past, the failure was totally bonkers, you know? In this case, it looked like everything was working perfectly except it just wouldn't finish counting the bonus. So odd.

This Gorgar has proven to be haunted by issues. Every hour that I run it, something else unrelated fails, but I'm working through things.

#11 7 months ago

Thanks for confirming the problem and solution!

And of course, the 0x47 0x72 0x65 0x61 0x74 0x20 0x6A 0x6F 0x62 0x21

decodes to

$ echo -e '\x47' '\x72' '\x65' '\x61' '\x74' '\x20' '\x6A' '\x6F' '\x62' '\x21'
G r e a t j o b !

#12 7 months ago
Quoted from DickHamill:

Maybe the speed of the countdown, which lamps are used for 1k, 2k, etc., or what sound is played with each 1k rewarded? I'm not sure what other parameters there are.

It's a lamp string with the lowest lamp #, the highest lamp # for the bonus, lamps representing the bonus multiplier, and some bytes representing the bonus value(s) at each multiplier. These are all in fixed locations in the game rom, none of which were as high up as you noted the error, so it's probably something the game does as part of the end of ball routine. $7A is 'dec $' and $7B is illegal, since $7B is actual byte you need, it's probably a parameter for something right before it.

Took a quick look, seems to be a script for either the main scripting engine or lamp scripting engine in system 6.... if it's something testing a parameter that could for sure cause the endless stuff.

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