> On Mar 13, 2021, at 1:34 PM, Joshua Rice via cctalk <cctalk@classiccmp.org>
> wrote:
>
>
>> Very interesting looking. I can't quite make out what is going on in that
>> rectangular area where all the wires terminate, labeled 0-15 and A-R. Are
>> there diodes there? Anything on the other side of that board?
>
> Nothing but traces on the other side, though you’re right on them being
> diodes.
>
>> The large cores with all the wires are remisniscent of core rope ROM. If
>> so, I wonder if it's AGC (Lincoln Labs) style, EL-X1 style, or a scheme
>> different from either of those two.
>
> It’s definitely some form of core rope ROM.
>
> Interestingly, the ferrite rings are built in pairs, with a "selection" coil
> wrapped around both, joining them. Therefore (i assume, i’m really no expert)
> they’ll be a positive pulse induced when passing through one coil, but a
> negative pulse when passed through the opposite coil. This probably helps in
> differentiating beween a 0, a 1, or a NULL state (ie 0v).
>
> I have no idea if that correlates with any particular format of Core Rope,
> but as far as my eyes can tell, that’ how the core rope is woven and
> functions.
The key component of core rope memory (and X1 ROM) is square-loop cores, like
the cores used in conventional read/write core memory.
There is another kind of core ROM where the cores are simply transformer cores.
Since you mentioned a "selection" coil, chances are that's what we're dealing
with here.
Brent Hilpert has a great writeup on a number of the technologies used.
http://madrona.ca/e/corerope/index.html
paul
