Post by thread:A simple question .....

On Tue, May 19, 1998 at 01:15:18AM -0400, Ricardo Ponte G wrote: > > "PICmicro FLASH device" so, what«s the mean of " FLASH device " It's a device that indecently exposes itself :-) Seriously, FLASH is a fancy term for a kind of electrically-erasable programmable read-only memory (EEPROM). The exact difference between FLASH and regular EEPROM depends on which marketing person you talk to, but basically FLASH is always bulk-erased, whereas (some) EEPROM can be byte erased. I think the original term came from the fact that it can be erased in a flash. Cheers, Clyde -- Clyde Smith-Stubbs | HI-TECH Software Email: spam_OUTclydeTakeThisOuThtsoft.com | Phone Fax WWW: http://www.htsoft.com/ | USA: (408) 490 2885 (408) 490 2885 PGP: finger .....clydeKILLspam@spam@htsoft.com | AUS: +61 7 3354 2411 +61 7 3354 2422 --------------------------------------------------------------------------- HI-TECH C: compiling the real world.

At 05:19 PM 19/05/98 +1000, you wrote: {Quote hidden}>On Tue, May 19, 1998 at 01:15:18AM -0400, Ricardo Ponte G wrote: >> >> "PICmicro FLASH device" so, what«s the mean of " FLASH device " > >It's a device that indecently exposes itself :-) > >Seriously, FLASH is a fancy term for a kind of electrically-erasable >programmable read-only memory (EEPROM). The exact difference between >FLASH and regular EEPROM depends on which marketing person you talk to, >but basically FLASH is always bulk-erased, whereas (some) EEPROM can be byte >erased. > >I think the original term came from the fact that it can be erased in a flash. > >Cheers, Clyde > >-- >Clyde Smith-Stubbs | HI-TECH Software >Email: clydeKILLspamhtsoft.com | Phone Fax >WWW: http://www.htsoft.com/ | USA: (408) 490 2885 (408) 490 2885 >PGP: finger .....clydeKILLspam.....htsoft.com | AUS: +61 7 3354 2411 +61 7 3354 2422 >--------------------------------------------------------------------------- >HI-TECH C: compiling the real world. > > Clyde is right, however the difference can be expanded somewhat more. A FLASH device must have all the bits set to 1 i.e. FF as it can only clear the bits in the macrocell i.e. wrtie a 0 to it (During programme), whereas an EEPROM can change the state of any bit. Also the FLASH device has 4 gates per memory cell, whereas; an EEPROM has 6. Dennis -=====================================================================- Dennis Plunkett: Embedded Hardware, Software design NEC Australia DRMASS Line Interface cards TRX software ISDN interface card ph 03 9264-3867 -=====================================================================-

Dennis Plunkett <RemoveMEdennisTakeThisOuTRDD.NECA.NEC.COM.AU> wrote: > Also the FLASH device has 4 gates > per memory cell, whereas; an EEPROM has 6. Actually, no. Maybe you're thinking of SRAM cells; low power CMOS SRAM uses six transistor cells, and higher density (but higher power) cells use four transistor cells. EPROM, EEPROM, and Flash all ususally use one transistor per cell, although it is an unusual transistor with a second "floating" gate. For very high speed memory, Sometimes a second transistor is added, because the same characteristics that make a good storage transistor also make a relatively slow switch. In the past EEPROM cells sometimes had two separate floating gate transistors for storing ones and zeros, and read the bits using differential sensing. In such devices, the erased (or unprogrammed) state was indeterminate. This was relatively common in the old MNOS (*) EEPROMs. However, I don't think this technique is much used any more. Maybe someone from Microchip would care to comment on how their Flash technology works? Cheers, Eric (*) Yes, I really meant MNOS. Not NMOS.

-----Original Message----- From: Clyde Smith-Stubbs <spamBeGoneclydespamBeGoneHTSOFT.COM> To: TakeThisOuTPICLISTEraseMEspam_OUTMITVMA.MIT.EDU <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> Date: Tuesday, May 19, 1998 4:39 AM Subject: Re: A simple question ..... ... >Seriously, FLASH is a fancy term for a kind of electrically-erasable >programmable read-only memory (EEPROM). The exact difference between >FLASH and regular EEPROM depends on which marketing person you talk to, >but basically FLASH is always bulk-erased, whereas (some) EEPROM can be byte >erased. > >I think the original term came from the fact that it can be erased in a flash. > >Cheers, Clyde > In a book "What a Great Idea" Charles "Chic" Thompson describes his interview with Yoshiro NakaMats (inventor of CD, floppy, digital watch etc. - more than 2,300 patents all together): ... C.T.: I've read that you come up with a patentable idea every day. Have you come up with one today? Y.N.: No, let's invent a product together. What would you buy if it were available? C.T.: I'd buy a recording device, about the size of a credit card, that could fit in my shirt pocket. Every time I had a flash of an idea, I could just record it. It would be voice activated, with a very large memory, and have a voice activated filing system for idea management. Y.N.: What would you call it? C.T.: I'd call it "Flash" - because it would just be flashes of ideas, which you could then download onto a computer system. Y.N.: Very good. This will be our first product together, so when I get home, I'll turn it over to my research department. .............. I am not sure, but could this be an origin of a term "Flash" memory? Gennady Palitsky gennadypEraseME.....mainlink.net