Core memory emulator using non volatile ram.

allison allisonportable at
Sun Dec 16 21:00:49 CST 2018

On 12/15/2018 09:32 PM, Charles Anthony via cctech wrote:
> On Sat, Dec 15, 2018 at 6:15 PM Rod G8DGR via cctalk <cctalk at>
> wrote:
>> All very interesting.. 1201 alarm while I deal will all of the information
>> Rod
> 1202 coming up...
> I don't know specifically about the various memory types being bandied
> about, but I do know that the destructive read behavior of core memory my
> be required for some architectures; "load and clear" type instructions rely
> on the suppressing the write-after-read cycle to make the instruction
> atomic, allowing the implementation of data locking instructions. For some
> architectures,  it may be that any replacement memory would have to support
> the suppression signal to work correctly.
> -- Charles

That's all fairy land speculation and guessing.  The person that started
this is working with
a PDP-8E so the above does not apply.  the 8E and later had both DEC
made ram and third
parties did when 2102 were cheap enough about 78ish.    Later it was
battery backed up
cmos.  For system with disk a rom based booter was enough as who cares
if the ram held
valid stuff.  As to realism, the cost of a core was high enough then if
it broke or worse now
if it breaks its out of sight.  Breakage back then was costly, not its
possibly unobtainium.

The for the most part with the covers on the only thing noted was binary
blisters from the
switches and the incessant loud fans.   In the mean time the user was
interacting with a
TTY with its notable noises and if needing service a sometimes bad
attitude.  The fact that
CORE does a R-Rewrite or RMW cycle is both unseen without a scope and
had no impact while
running a file though PAL-III in all caps.

In the end, current generation CMOS ram is the easy out, battery is
small, cost is small,  and
produces much less of the heat that is killer to systems.   The only
reason to do that is core
cost big if you can find it for your machine.  I can cost more if you
want to run an OS that
needs a fair amount of it.  AC as well as it can help heat the room and
also power as in
makes the meter spin.

So much lathering and speculation about what and how.  When the point is
totally missed.


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