> Generally, the fastest way to logically delete data is to just forget that it's there. RAM works the same way, as would any other medium that doesn't have any special requirements for writing.
Many media have special requirements for writing. It's true that DRAM and SRAM don't have a separate "erased" state, and neither do fuse PROM, core memory, Williams tubes, acoustic delay lines, or magnetic disk and tape.
But CD-R, Flash, CD-RW, rewritable magneto-optical disks, two-photon storage, and some other memory types have a distinct "erased" state; in some cases, you can't even return to that state. I'm not sure about MRAM, FeRAM, PRAM, and hypothetical memristive memories.
Many media have special requirements for writing. It's true that DRAM and SRAM don't have a separate "erased" state, and neither do fuse PROM, core memory, Williams tubes, acoustic delay lines, or magnetic disk and tape.
But CD-R, Flash, CD-RW, rewritable magneto-optical disks, two-photon storage, and some other memory types have a distinct "erased" state; in some cases, you can't even return to that state. I'm not sure about MRAM, FeRAM, PRAM, and hypothetical memristive memories.