11 Mar
2005
11 Mar
'05
12:50 p.m.
Eric Smith wrote:
Ramtron ferroelectric RAM (nonvolatile) is available
from Newark
Electronics. The traditional problem with FRAM is that it had limited
read endurance, as well as limited write endurance. Just reading the
part would wear it out. The newest 3V parts have fixed that.
The FM18L08 is a 32K*8 3V 70ns part with unlimited endurance. IIRC,
the last time I bought some from Newark I paid under $10 each.
But is that DIP packaging? I got the data sheet but interfacing to 5v
logic and power
up is where I have lack of knowlage. I still think a generic FRAM
board needs
to be made with 3V parts to replace CORE memory in older machines
but I have
no idea how to interface 3V logic with 5 volt logic NOT using CMOS parts.
There is a newer 128K*8 55ns part, the FM20L08. Newark
doesn't have
it yet. All American Direct gives a price of $25.59, but it is not
clear whether they actually have parts in stock.
I still am dealing with classic small machines ... 2 FM18L08's replace a
whole rack of
core memory for a PDP/8. @ 2 cents a bit that is $8K for 8 banks of 4K
word memory
or $500 1980? $ for 4K.
If you want to use these in a 5V system, it's
probably a good idea
to use some 74LVC buffers that can function as level translators.
SMT I think.
Eric
Looking at orginal PDP / 8 ( 1965) prices $800 for a paper tape
punch/reader today is
a great deal. $15,000 would buy you a home back then.
Ben