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.