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: http://www.minuszerodegrees.net/memory/4164.htm NEC 4164 use 128 cycle refresh, but so do many others. --Chuck
