> From: Paul Koning <paulkon...@comcast.net> >>> 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)? Noel