4264 vs. 2164 RAM chips

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Zippy Zapp
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Re: 4264 vs. 2164 RAM chips

Post by Zippy Zapp »

Ok cool. Beyond the VSP fix there are not other compatibility problems by the switch? Sounds like a good idea.


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rmzalbar
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Re: 4264 vs. 2164 RAM chips

Post by rmzalbar »

Nope.. none that I'm aware of.
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Re: 4264 vs. 2164 RAM chips

Post by banman »

Hi Gyro Gearloose,
I was doing some research online on RAM chip identifying numbers and Google brought this thread up.
Gyro Gearloose wrote: Wed Jun 19, 2019 3:06 am Hmmm, forgive my intrusion upon this learned discussion, but I think you can just pop in a 41256 chip in lieu of a 4164 and it should work as a 64k chip. The C64 will simply never address the extra memory.
The extra A8 line on the 41256 would be left floating, so you'd need to tie it to a low-impedance logic level, just strap a wire across to pin 16.
Anyone ever try this?
I actually have a quantity of KM41C256P RAM chips. I'm willing to give this a go.

IMG_20200829_134752.jpg


If I read you right I need to run a jumper wire from pin 1 across the top of the chip on to the GND pin 16 of the KM41C256P RAM chip. Then would I insert the chip as normal into a RAM socket with no lifting of the RAM legs?
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Gyro Gearloose
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Re: 4264 vs. 2164 RAM chips

Post by Gyro Gearloose »

Yes. If you already have sockets and you know that the 41256 chip is good, should be a simple hack. You just need to try with one.
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Re: 4264 vs. 2164 RAM chips

Post by banman »

Hi Gyro Gearloose,


Okay, good. Thank you for the information.


I'll get back to you.
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Re: 4264 vs. 2164 RAM chips

Post by banman »

Hi Gyro Gearloose,

Yes, I just tried several of them. I can say they work fine.


I am surprised they work considering the manner they were stored in for 30 odd years and how I was handling them recently.

I must say I didn't realize they were CMOS style until I started looking up datasheets.

I tried two chips and both worked fine.





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Gyro Gearloose
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Re: 4264 vs. 2164 RAM chips

Post by Gyro Gearloose »

There we go. Something positive in 2020 finally.
The price one pays for pursuing any profession, or calling, is an intimate knowledge of its ugly side.
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Re: 4264 vs. 2164 RAM chips

Post by banman »

Hi Gyro Gearloose,

Absolutely! I can't wait to put Covid19 behind us......

I was doing some online research related to tracking down some IC part numbers and found this interesting site talking about which 4164 64K x 1 DRAM chips worked in a Atari800XL from a stock C64 memory chips.



https://atariage.com/forums/topic/22716 ... computers/



Here's a few screenshots from this site with a table of suitable 4164 64K x 1 DRAM chips.....

Screenshot_2020-10-13-12-09-46-623_com.android.chrome.png
Screenshot_2020-10-13-11-55-04-358_com.android.chrome.png
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