NEC 4164-12

dwight dkelvey at
Sun Oct 29 08:30:52 CDT 2017

Nice chart Chuck.


From: cctalk <cctalk-bounces at> on behalf of Chuck Guzis via cctalk <cctalk at>
Sent: Saturday, October 28, 2017 10:19:53 PM
To: dwight via cctalk
Subject: Re: NEC 4164-12

On 10/28/2017 10:14 PM, dwight via cctalk wrote:
> One caution for 4164s. When they first came out, there were some that were 256 cycle refresh and others that were 128 cycle.
> There is no way by looking at them to tell which is which other than getting a matching original manufacture document.
> Many machines expect 128 cycle. You can use 256 cycle on chips designed for 128 but not the other way around.
> Most Z80 setups only do 128 unless it has additional hardware to handle the extra bit ( not to likely ).

There's a great chart of the 4164s and their characteristics here:

NEC 4164 use 128 cycle refresh, but so do many others.


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