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On Wed, Mar 01, 2006 at 04:16:33PM -0500, Ryan Holt wrote: |
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> Is there any difference between ROM and NVRam? |
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Yes. ROM is a WORM medium (write once, ready many times). The data |
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stored in a PROM (programmable read only memory) is literally burned |
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in by applying high-voltage pulses to the chip. |
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There's also EPROM (eraseable PROM) which can be erased by exposing |
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the chip to ultraviolet light, and EEPROM (electrically eraseable |
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PROM). If we're being pedantic, ROM is a misnomer for these, since |
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they're not really "write once". |
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NVRAM (non-volatile random access memory) is similar to EEPROM in some |
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ways: it can be written and erased many times, and maintains its data |
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even when power is disconnected. MRAM, FRAM, etc. are forms of |
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NVRAM. Flash memory is I believe a more modern form of EEPROM. They |
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all differ in the physical technology used on the chip, and have |
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different properties, such as how many times the memory can be erased |
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and rewritten, how fast writing and reading is, etc. |
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Also, Wikipedia says: |
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"...there is a convention to reserve the term EEPROM [for] byte-wise |
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writable memories compared to block-wise writable flash memories." |
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> I think I mis-spoke when I said ROM; because it's actually Non Volatile Ram. |
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You *could* have meant PROM, but NVRAM sounds much more likely ;-) |
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Toby |
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-- |
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PhD Student |
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Quantum Information Theory group |
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Max Planck Institute for Quantum Optics |
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Garching, Germany |
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email: toby@××××××××.org |
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web: www.dr-qubit.org |
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-- |
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