Bad memory in the extended memory of the 80 column RGB card

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Joined: Sep 21 2014
Posts: 74

I used the sequence which tested the memory, and returned the following over several iterations

*RAM ZP 0 0 0 0 0 0 0 1
*RAM ZP 0 0 0 1 0 0 0 0
*RAM ZP 0 1 0 0 0 0 0 0

Does anyone have a source for replacement ram chips?

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Joined: Sep 21 2014
Posts: 74
Re: Bad memory in the extended memory of the 80 column RGB card

Have I stumped the community with this one?

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Joined: Oct 9 2013
Posts: 367
Re: Bad memory in the extended memory of the 80 column RGB card

The 80 col/RGB card I have uses 4264-15's. I've seen ones with 4264-20's as well.

Typically I use Jameco.com or Digikey.com for most stuff but a quick search did not pull those up at either site.

Questcomp currently has the same MT4264-15 ICs that are on the card I have (they say 67 left in stock)

Try This Link and see if that's what you are looking for.
Zan

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Joined: Oct 9 2013
Posts: 367
Re: Bad memory in the extended memory of the 80 column RGB card

By the way, findchips.com came up with several possible sources. I have bought from questcomp before which is why I posted that link.

I did not price compare or aything so you may have better luck elsewhere.
Zan

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Joined: May 9 2010
Posts: 11
Re: Bad memory in the extended memory of the 80 column RGB card

There are M A N Y on eBay
like this

251391724000
or
251666089003
or
251706413153

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Joined: Apr 1 2005
Posts: 117
Re: Bad memory in the extended memory of the 80 column RGB card

(removed)

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Joined: Sep 21 2014
Posts: 74
Re: Bad memory in the extended memory of the 80 column RGB card

Thanks for the replies I have purchased the replacement chips from the info you provided

MarkO's picture
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Joined: Dec 10 2011
Posts: 667
Re: Bad memory in the extended memory of the 80 column RGB card

Zan8675 wrote:

The 80 col/RGB card I have uses 4264-15's. I've seen ones with 4264-20's as well.

Typically I use Jameco.com or Digikey.com for most stuff but a quick search did not pull those up at either site.

Questcomp currently has the same MT4264-15 ICs that are on the card I have (they say 67 left in stock)

Try This Link and see if that's what you are looking for.
Zan

Quest Components is Golden!!!

Where I work, we have sourced older components from them, with excellent results.. ( I am the Maintainer and Repairer of the Older Products that were made. Supporting older products will always get you good will with Current Customers, as well as Future Customers... )

I would buy from them again. And most likely will.

MarkO

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Joined: May 27 2013
Posts: 794
Re: Bad memory in the extended memory of the 80 column RGB card

Zan8675 wrote:

The 80 col/RGB card I have uses 4264-15's. I've seen ones with 4264-20's as well.

Typically I use Jameco.com or Digikey.com for most stuff but a quick search did not pull those up at either site.

Questcomp currently has the same MT4264-15 ICs that are on the card I have (they say 67 left in stock)

Try This Link and see if that's what you are looking for.
Zan

I could not find a datasheet on the particular chips I had originally on my apple iie. They were the Texas Instruments TMS4164-15NLJ.

One of the chips was bad so I ordered an 80 column card that I knew had 8 memory chips on it. I installed the chips on my iie and it works fine now.

But now I am stuck on an 80 column card and only 7 chips.

The card has two part numbers on it:

820-0067-B and 607-0103.

Do the listings on questcomp (MT4264-15) or (TMS4164-15NL) match the chips that will work with this memory card?

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Joined: Sep 21 2014
Posts: 74
Re: Bad memory in the extended memory of the 80 column RGB card

So the chips arrived today, not having a reference for which one is 1 and which one is 8, i did a best guess and swapped two chips.

The computer showed the error MMU over and over
and once in a while showed 00010000 not knowing which one was 5 i decided to pull one chip and reinsert the board.
with the one chip mising, i get the beep and the System OK.

Now im confused. is the 80 column card borked in my computer?
can I introduce one chip at a time into it or must all the banks be occupied?

Jordan

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Joined: Sep 21 2014
Posts: 74
SOLVED Bad memory in the extended mem of the 80 column RGB card

I got it

Staring at the card with the 8 chips to the left

8 7
6 5
4 3
2 1

mission accomplished