Core memory emulator using non volatile ram.

Noel Chiappa jnc at
Tue Dec 18 18:30:55 CST 2018

    > From: Paul Koning <paulkoning at>

    >>> core memory details such as destructive read weren't visible to the
    >>> CPU

    > DATAIP/DATAO on the Unibus doesn't depend on the destructive read
    > property. 

Yes, the CPU can't tell what the memory is doing.

    > The reason it existed is that it allows core memory to optimize the
    > timing

In other words, it's only there to allow the CPU to act in a way that works
well with core memory. Whether that means that the way core operates is
"visible" to the CPU is a debate about definitions.

Put it another way - do any modern CPU's do 'read-modify-write' cycles (other
than for interlocks in a multi-CPU system)?


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