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Primary Storage: Memory

Primary Storage: Memory. Primary storage is directly accessible by the processor Memory: RAM = random access memory ROM = read only memory PROM/EPROM = programmable ROM RAM is volatile (not retained w/o power) cache, interrupts, memory, flags…. Secondary: Mass Data Storage .

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Primary Storage: Memory

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  1. Primary Storage: Memory • Primary storage is directly accessible by the processor • Memory: • RAM = random access memory • ROM = read only memory • PROM/EPROM = programmable ROM • RAM is volatile (not retained w/o power) • cache, interrupts, memory, flags…

  2. Secondary: Mass Data Storage • primary storage is directly accessible by the CPU (RAM, cache memory) • secondary storage is not directly accessed • data is transferred to primary memory when needed by processor • MDS is non-volatile - record and modify information (semi-)permanently

  3. Types of MDS • Punched surfaces - earliest method; human readable - punched cards, punched tape • Magnetic surfaces - most widely used - streaming tape, magnetic disks (floppy, hard, zip…) • Optical surfaces - most durable - optical disks (CD-ROM, laserdisc, DVD…)

  4. media: size/capacity: advantages: disadvantages: Floppy 3.5” = 720KB, 1.44MB, 2.88 5 ¼” = 360, 720KB (old) 8” = 180, 360KB (old) inexpensive; shareable slow; effected by magnetic fields, dirt, temp; corruptible Hard ¼, half & full height, 51/4”, 8” = 5MB… 100+GB? fastest not usually portable; not expandable Optical CD = 4.5” = 80-650MBdata/74minAudio Laser = 8”,12” DVD = 3.8 - 17GB massive capacity, high reliability, portability, data & audio standard read only Removable Clik = 25 - 40MB Zip = 100-250MB Jaz = 500M - 2GB SuperDisk (3M - Imation) =120MB faster & more capacity than floppies; read/writeable slower than hard; more expensive than floppies Magneto-optical MO combination of technologies reliable; high capacity expensive; not as fast Flash Memory (newest) solid state storage; memory sticks; flashcards no moving parts, rewritable very expensive; no standard yet Comparisons of MDS types

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