Author Topic: 2716 ROM replace, can I use flash?  (Read 311 times)

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Offline johnsonlam

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2716 ROM replace, can I use flash?
« on: October 13, 2020, 01:04:35 am »
Hi,

Got an old Apple //e which keyboard ROM seems have some problem, it's an 2716 ROM but it's now obsolete, don't want to buy the Chinese old one, as they maybe fake or fail soon. Remember see some post that can replace with 27C256 (which I have an ATMEL OTP), but how to do this? Seems need an adapter or some pins modified, please advise.

Thanks in advance.

Rgds,
Johnson.
 

Offline edavid

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Re: 2716 ROM replace, can I use flash?
« Reply #1 on: October 13, 2020, 02:07:17 am »
You can use a 28C16, no adapter needed.
 
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Offline johnsonlam

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Re: 2716 ROM replace, can I use flash?
« Reply #2 on: October 13, 2020, 02:28:21 am »
Seems it's obsolete and can't buy from Digikey and Mouser, only AliExpress and eBay have old stock  :(
« Last Edit: October 13, 2020, 02:29:53 am by johnsonlam »
 

Offline terminus

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Re: 2716 ROM replace, can I use flash?
« Reply #3 on: October 13, 2020, 04:42:24 pm »
Hi Johnson,

did you try to reprogram it? it could simply be beyond the data retention period.

wbr
victor
 

Offline Benta

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Re: 2716 ROM replace, can I use flash?
« Reply #4 on: October 13, 2020, 05:52:14 pm »
For an old Apple, it probably a DIP package. Choose some SOIC/SSOIC EEPROM or Flash, use an SO-to-DIP adapter PCB (can be bought ready-made) and you're done.
 

Online james_s

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Re: 2716 ROM replace, can I use flash?
« Reply #5 on: October 13, 2020, 06:49:42 pm »
I've bought lots of EPROMs from China sellers and haven't had an issue yet, the quartz window ICs will be used pulls in most cases but not fake. The EEPROMs you have to be more careful with, I got burned on some 28xx parts that turned out to be some random IC that had been blacktopped and re-marked.

You  might also try simply re-programming the EPROM you already have. I've had them fade before and get corrupted and have been able to refresh them in my TL866 and they worked again.
 

Offline greenpossum

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Re: 2716 ROM replace, can I use flash?
« Reply #6 on: October 13, 2020, 06:51:34 pm »
For just over a buck a 28C16 is worth risking. If you were local I could send you one I extracted from old equipment. I also have some 2732s. You need a programmer capable of handling the voltages. Otherwise you could make an adaptor from larger (E)EPROMs which are in a 28 pin package rather than 24 pin. You just need to ground the extra address lines. Tedious and you may not have the vertical space.
 


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