Memory Cards

DIFFERENT MEMORY CARDS

Let's see if I can run through the alphabet soup of memory:

ROM = Read Only Memory

The first one costs $500,000 -- but the 2nd one only costs a buck. Buy lots! Lowest cost, highest density memory chip.

PROM = Programmable ROM.

A PROM can be "burned" with any information you want, but it can only be done once. Per-unit cost is higher than ROM, and density isn't as high -- but there's no massive setup cost. You do need a PROM burner -- a specialized piece of electronics.

EPROM = Erasable PROM.

This is a PROM that can be erased with a long dose of intense ultraviolet light. EPROMs have small windows in the top through which the UV is sent; in normal use, a piece of tape covers the window to prevent unintentional erasure. More expensive/less dense than PROMs, but mistakes aren't as expensive.

EEPROM = Electronically erasable PROM.

Same concept, only it can be erased electronically.

Flash RAM

A new kind of EEPROM which allows the chip to be modified byte by byte. Flash RAM seems to be breaking the traditional tradeoff between flexibility and cost, with densities much higher than EEPROM yet with lower costs.

Ted Dickens (HP Forums Sysop)

CompuServe ID: [76701,272]