Jelena Mamčenko Operating Systems Lecture Notes on Operating Systems 13of time. A particular location in storage is selected by its physical memory address. That address remains the same, no matter how the particular value stored there changes. 8.1Technology and history Today, primary storage is typically random access memory, a type of semiconductor memory. Over the history of computing hardware, a variety of technologies have been used for primary storage. Some early computers used mercury delay lines, in which a series of acoustic pulses were sent along a tube filled with mercury. When the pulse reached the end of the tube, the circuitry detected whether the pulse represented a binary 1 or 0 and caused the oscillator at the beginning of the line to repeat the pulse. Other early computers stored primary memory on rapidly rotating magnetic drums. Modern primary storage devices include: •Random access memory (RAM) - includes VRAM, WRAM, NVRAM •Read-only memory (ROM) 9Expansion card
This is the end of the preview.
access the rest of the document.