Having the drivers is important. I've looked in vain
for the 75xxx series chips described in the famous
1976-ish Byte Magazine article on core memory that has
been mentioned before. Without those, its a heck of a
lot of discretes, and there's no way around it. Too
bad, because I have some really nice core memory with
the diodes only that deserves to do more than hang on
a wall. I also suspect that because of all of the
unknowns involved regarding the magnetic properties of
the core that you use, the way to go about it is to
put a lot of pots on a single driver/receiver setup,
tweek em to the middle, and repeat. My understanding
of core is that there are thermistors involved also,
and that core had a very narrow range of temperature
operation. There were even programs designed
specifically to cause "hot spots" in the core in order
to test it (you'd have to know the physical layout of
the core to pull this trick off).
--- Joe <rigdonj_at_cfl.rr.com> wrote:
> Bill,
>
> You're a man after my own heart! I've been
> thinking about this for some time. I once had some
> NICE small core planes (16k I think) out of a HP
> communications analyzer and I think they would have
> been just about perfect for this. I had too many
> other projects at the time so I sold them but I know
> where there are some more analyzers so I may grab
> them and swipe the core from them. I found the
> service manual for the analyzer so I had the pin out
> for the entire machine including the core. (I still
> have it). IIRC the core module was about 5 inches
> square and had all the drivers and sense amps on it
> so that might make things easier. However there are
> some things that you have to do with core and I
> don't know if they handled in hardware or if the OS
> had to take care of it. For example, reading core is
> destructive, that is it erases the contents so you
> have to store the contents back into it before you
> do anything else (unless you don't care if it's
> lost). That seems like it wou!
> ld be easy enough to do in HW but I don't know if
> that's what they did.
>
> Joe
>
> At 11:41 AM 4/3/02 -0600, you wrote:
> >Right off, let me say that I know next to nothing
> about the realities of
> >using core memory. I only know that it looks like
> pretty cool stuff to
> >play with. Would I be completely off my tree to
> try to build a core
> >memory interface from scratch, assuming I had a
> pre-strung core frame with
> >all the cores and wires intact? When I say
> "interface", I mean basically
> >something that will let me talk to the core from a
> PC or from my
> >recently-completed Mark-8 using TTL or CMOS levels.
> If I have a 64x64
> >frame, would I just need something on the order of
> 256 driver transistors
> >(one to drive each of the X and Y wires in either
> direction) plus some
> >kind of op-amp or comparator circuit to monitor the
> sense wire (is there
> >just one of these per frame?) and determine whether
> or not a bit has
> >flipped during a read pulse? Or are there all
> sorts of ghosts and goblins
> >lurking in core memory that I don't want to
> confront?
> >
> >
> >
> >
>
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Received on Wed Apr 03 2002 - 14:27:46 BST