2 Feb
2023
2 Feb
'23
3:17 p.m.
On 2/1/23 22:10, Will Cooke via cctalk wrote:
I have extreme doubts that this is true. Memory cores are
just tiny versions of pulse transformers, and similar square
loop transformer core materials are used in switching power
supplies that run for decades at high switching
frequencies. Really, FRAM does not work much similarly to
core. The ferroelectric material is usually lead zirconate
titanate, not an actual ferromagnetic material. It is
written by an electric field, not magnetic, and the electric
field is sensed by a field effect transistor. I have NEVER
heard of core wear-out in magnetic core memories. The
flipping of the magnetic polarization in ferrite materials
does not break down the crystal structure.
Jon
Jon
On 02/01/2023 3:51 PM CST Paul Koning via cctalk
<cctalk(a)classiccmp.org> wrote:
ot sure about that. What sort of numbers are we talking about?
If all else fails there's core memory, which
as far as I remember is pretty much unlimited for both read and write.
paul
I don't know for sure and can't find any references, but I strongly
suspect that core memory would wear out over time, as well. My reasoning for this is the
because in principle it works the same as FRAM. I usually refer to FRAM as "core on
a chip." Over time, the magnetic domains in FRAM tend to stay in one polarization or
another. I see no reason why the magnetic domains in core wouldn't do the same.
However, a single core is probably bigger than the entire FRAM chip so there are a LOT
more domains. That means it would take a proportional amount of writes to wear out --
let's just say a million times. In addition, core access was in microseconds, whereas
FRAM and other modern memories are in nanoseconds. So it takes something like 1000 times
longer on the clock on the wall to perform the same number of writes. So in the end
something like a billion times longer on the calendar to wear it out.
I would be very interested if anyone actually knows and especially if there are
references available.