ITPEC FE Morning October 2019 Question 23

Which of the following is an appropriate description of flash memory?

a)All its contents can be erased at once with ultraviolet rays.b)Data can be electronically erased in block units.c)It can be rewritten at a high speed and is used for the cache memory of a CPU.d)It needs to rewrite data periodically.

Explanation

Data can be electronically erased in block units — flash memory is non-volatile memory that is erased electrically, a whole block at a time.

Flash memory keeps its data without power, like the EEPROM it was developed from, but instead of erasing byte by byte it erases a block of many pages in one electrical operation, which makes it cheap and dense. That is why it is used in SSDs, USB memory and memory cards.

Answer (b)

Why not others:

•(a) — erasing the whole chip with ultraviolet light through a window in the package is EPROM
•(c) — fast rewriting for CPU cache is SRAM; flash is far slower to write and wears out after a limited number of erase cycles
•(d) — periodic rewriting, refresh, is needed by DRAM, which stores bits as charge in capacitors that leak

Key rule: Match each memory by how its contents are kept or erased: DRAM refresh, SRAM no refresh and fast (cache), EPROM ultraviolet, EEPROM electrically by byte, flash electrically by block.

Computer Component · AI-written, may contain errors

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