11 Nov
2008
11 Nov
'08
2:40 p.m.
From: dwight elvey <dkelvey at hotmail.com>
Shouldn't that be one digital scope channel for every bit in the word?
From: ard at p850ug1.demon.co.uk
Hi
Reading shouldn't be too difficult. Outputs could be recorded by
a digital scope.
Those of you with experience reading cores, we need your help in
reading out a LVDC core stack.
Ouch!. I don't have much experience of reading core, but I've
worked on
core memory systems (I guess many others here have too).
Rememebr that reading core is destructive. Basically, the read
operation
is to write a 0 to each core and see if there was a change in
magnetic
flux in that core. If there was, it _was_ a 1. If not, it was (and
still
is) a 0. Normally you then write the 1 back if appropriate.
The rise times of the address and inhibit lines
Do we know this core memory has "inhibit lines"? My only core
experience is with 2D planes and I've not heard of inhibit lines,
maybe they are the magic that allowed 3D stacks to be made. On my
core, half the current required is supplied on two separate wires, if
you don't know the current required and you send the critical amount
down one wire you will clear the entire memory in one go.
are mostly to be slow enough that it doesn't cause the sense
amplifier to trip on the coupling in the selected address line.
Other addresses are protected by the matching signal on the inhibit
line. Any reasonably slow ramp would work since one is using a
scope to record and not a sense amp.
The levels needed can be determined experimentally since the amplitude
of the read signal is indepedent of the address signal size
( assumming
that there is sufficient signal to cause the core to switch ).
There is little leakage of flux outside of the cores. Any method
to read an exterenal flux would be difficult to detect. I doubt
a hall efect would be sensitive enough. Maybe a SQUID could be used.
There are ones that are used to detect small shorts inside of
IC packages.
Still, I think the easiest method is as I described, using an
electrical
method and tries using small increments in the current.
Dwight