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Functions and uses of primary storage devices

Functions and uses of primary storage devices. Bistable devices, PROM, EPROM, EEPROM, Flash. As previously mentioned there are two types of primary storage devices; RAM and ROM . These are made from silicon chips consisting of many electronic circuits. Random Access Memory.

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Functions and uses of primary storage devices

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  1. Functions and uses of primary storage devices Bistable devices, PROM, EPROM, EEPROM, Flash

  2. As previously mentioned there are two types of primary storage devices; RAM and ROM. • These are made from silicon chips consisting of many electronic circuits.

  3. Random Access Memory • The contents of RAM can be randomly accessed. • Contents of RAM can not only be read but also be written to unlike ROM. • There are variations of RAM which include: SRAM and DRAM.

  4. DRAM (Dynamic RAM) • This is the most common type of RAM. • It must be constantly reenergized or it will lose its contents. • Other variations include; SDRAM – Synchronous DRAM and RDRAM – Rambus DRAM. • These have faster access than DRAM with RDRAM being the fastest

  5. SRAM (Static RAM) • It is faster and more reliable than any variations of DRAM. • It is more expensive than DRAM and does not have to be reenergized as often as DRAM.

  6. Read Only Memory • The contents can only be read and cannot be changed when ROM is being used by the computer. • ROM is not only found in computers. Most devices with electronic components such as microwaves, cell phones, videos contain ROM chips. • There are various types of ROM. These include PROM, EPROM and EEPROM.

  7. Programmable Read Only Memory (PROM) • Can be programmed with a special machine. • Once it is programmed, its contents cannot be changed (programmed once).

  8. Erasable Programmable Read Only Memory (EPROM) • Designed so its contents can be erased using ultra-violet light, then its contents be reprogrammed. • Can be reprogrammed several times. • Contents do not last as long as other types of ROM. • Must protect EPROM chips from exposure to sunlight.

  9. Electrically Erasable Programmable Read Only Memory (EEPROM) • Typically used to store code. • Similar to EPROM, however the erase operation is performed electrically. • Data may be erased and rewritten.

  10. USB Flash • Used for easy and fast information storage in devices such as digital cameras and video games. • A type of EEPROM chip. • Stores large amounts of data. • Low cost. • Non-volatile. • Electrically re-programmable. • Fast ( to read, but not to write).

  11. Bistable Devices • These are the foundation of digital electronics. • A bistable device can exist in two possible states, similar to an on/off switch. • Another example is a key on a keyboard – it can be either up/down.

  12. References • Oxford Information Technology for CXC CSEC by Glenda Gay, Ronald Blades • CXC Information Technology by Kelvin Skeete

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