accordion angle bell labs bell system bit bubble memory communications in colombia communications in mexico ddr sdram delay line memory drum memory dynamic random access memory eeprom eprom ferroelectric ram flash memory floppy disk hard disk drive helix magnet magnetic core memory magnetic ink character recognition magnetic storage magnetic stripe card magnetic tape magnetoresistive random access memory ncr cram nano-ram non-volatile memory phase-change memory plated wire memory programmable metallization cell programmable read-only memory racetrack memory random-access memory read-only memory resistive random-access memory sonos selectron tube solenoid static random access memory telephone switchboard traffic service position system twin transistor ram volatile memory williams tube wire recording z-ram