| ??? 10/17/08 20:31 Read: times |
#159169 - it is SERIAL EEPROM Responding to: ???'s previous message |
Andy Neil said:
Richard Erlacher said:
If EPROM is now a generic term, how's one to interpret whether it's an EPROM, EEPROM, FLASH, SEEPROM, NVRAM, FRAM, MRAM, or whatever? What do you mean by SEEPROM? It's Serial EEPROM. But NVRAM, FRAM, and MRAM are not ROM at all - so the problem doesn't arise!
In that case, you could say that FLASH and EEPROM aren't ROM either! But it does raise another issue: "RAM" simply stands for Random Access Memory (as distinct from sequential access memory); it doesn't actually say anything about whether it is read-only, or read-write - and neither does it actually say anything about whether the storage is volatile or not...
;-) Well, FLASH certainly isn't random-access for writes, is it? Some FLASH devices have to be read in sectors, too. That's not random-access. I don't see a point in rummaging through all the possible semantic combinations and permuations. Everybody knows what an EPROM is, and they know what the difference between EPROM and EEPROM is, or, at least, should. They should also know the difference between EEPROM and FLASH memory, and then they need to know the differences between NAND and NOR FLASH technology. Whenever I see someone refer to a device functioning as a read-only-memory, I call it a ROM despite the fact it may, in fact be a RAM of one sort or another. After all, its function determines what it is. You can argue whether a gate is an AND or a NOR, and you can argue about whether a flipflop is R/S or 'D', but if you use it as a given function, that defines what it is. The manufacturers don't have a problem defining what the device is ... if it starts with 27-something, it's an EPROM, UV-erasable if at all, and if it starts with 28-something, it's electrically erasable, and probably EEPROM. If it's flash, well, the numbers vary. Likewise, if your MCU says 87-something, it's probably EPROM, and only can be erased with UV, while if it's 89-something, well, all bets are off. I believe we should strive for clarity, rather than "muddying the water" with such semantic gymnastics. RE |
