(Topic ID: 300564)

Can I Add A Memory-Protect Circuit To A Flash?

By clodpole

2 years ago



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  • 7 posts
  • 3 Pinsiders participating
  • Latest reply 2 years ago by clodpole
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#1 2 years ago

My Flash never had a memory protect switch. It has 4 new Pinball PCB boards and is inclined to corrupt its settings. I'm wondering if I can add a memory protect circuit to fix that defect?

If you've done something like this, I'd love to learn from your experience.

For that matter, if you have other suggestions re: the memory corrupting problem, I'll happlily listen to those as well.

Thanks.

#2 2 years ago

interesting read https://www.coinopcauldron.com/memprot.html

sounds like low power to the 5101 can cause issues.

assuming with 4 new boards you have a non volatile ram hence no battery?

#3 2 years ago
Quoted from Rikoshay:

interesting read https://www.coinopcauldron.com/memprot.html
sounds like low power to the 5101 can cause issues.
assuming with 4 new boards you have a non volatile ram hence no battery?

Sorry for the late reply... yes, I have NVRAM and no battery. My memory corruption events seem associated with on/off cycles, and your document refers to those as potential low power events.

Anyway, the Kohout brothers, makers of my boards, believe my addition of a memory protect switch will work. Their boards are based on system 7.

I have to go out of town for a week; I'll let you know when I get the switch installed how it seems to be working.

#4 2 years ago

The memory protect switch in Sys 6 and later does not write protect the whole CMOS RAM, only the area that contains settings. Otherwise the bookkeeping data could not be written to cmos. If you have problems with cmos data corruption, adding a memory protect switch would not help.

You should check the part of MPU circuitry that disables CMOS RAM (or the NVRAM in your case) when supply voltage drops. Since you dont have original boards, I cant tell how it works in your board.

#5 2 years ago
Quoted from Tuukka:

The memory protect switch in Sys 6 and later does not write protect the whole CMOS RAM, only the area that contains settings. Otherwise the bookkeeping data could not be written to cmos. If you have problems with cmos data corruption, adding a memory protect switch would not help.
You should check the part of MPU circuitry that disables CMOS RAM (or the NVRAM in your case) when supply voltage drops. Since you dont have original boards, I cant tell how it works in your board.

Only settings, not CMOS, get corrupted. Sometimes in funny ways - coin slot multiplier, for example, which suddenly gives a lot of games for a quarter!

4 months later
#6 2 years ago

Well, the memory protect switch has been in my Flash now for a month. So far, so good. No newly corrupted settings.

Bracket (resized).jpgBracket (resized).jpgSwitch (resized).jpgSwitch (resized).jpg
1 month later
#7 2 years ago

Update: 3 months and no corrupted settings. I think the memory protect switch is working.

It wasn't terribly hard to cobble together and seems to have cured a very long-running annoyance.

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