where to find info

ron.boley ron.boley at worldnet.att.net
Sun Nov 1 12:10:19 GMT 1998


Geoff,

You need to look at some of the semiconductor sites.  Intel, AMD,
National Semiconductor and more.  The generic term implies a
non-volitile memory device (doesn't loose it memory when the power is
removed).  Early versions 70' and '80s were based on UV-Erasable
technology (Ultaviolet light they have quartz windows in them) others
were EEPROM (Electronically Erasable Programmable Read Only Memory). 
Flash memory came out in the early '90's which has generally replaced
the older EPROM and EEPROM is most devices.  The beauty of Flash and
older EEPROM is that it could be erased and reprogrammed while in a
device where as EPROM usually required removal.  Todays FLash devices
(Intel and AMD) have multiple sections where you can both store code and
variables, as well as keep the latest change data on the product.  AN
example on an ECC might be run the car and collect OBD-II data.  In many
cases engineers may combine Flash memory with a smaller EEPROM.  The
flash holds the program while the EEPROM holds the every day data
(OBD-II).  I hope this gets you started.

Ron Boley


Geoff & Sue Richards wrote:
> 
> Could someone be able to tell me of any books or web sites that can explain
> the workings of a prom?
> I have searched the archives in vain,any references to proms are for those
> that already know how these work
> I would like to understand addresses and maps etc
> TIA
> Geoff



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