Re: Possible new hardware project

[dempson@actrix.gen.nz (David Empson)]

Phoenyx <quazar@dcnet2000.com> wrote:

> Well, it may actually be Flash Rom, but the card I have claimed
> Ram. It is designed to write a finite number of times, in the
> thousands, but still limited.

Sounds like flash ROM to me.  They have misnamed the product.

The terms "ROM" and "RAM" have become rather sloppy over the years.
Original ROMs really were read-only, but more recent variants have
become more easily writable.

Mask programmed ROMs are hard wired at manufacture time, and cannot be
reprogrammed.

PROMs can be programmed once.  (In most cases, each bit starts out as a
"1" and can be programmed to "0", but not back again.)

EPROMs are like PROMs, but can be erased with an ultraviolet light.
Both PROMs and EPROMs are usually rewritten by removing them from the
system and using a special programmer.

An EEPROM is like an EPROM, but it can be erased electrically.  In many
cases, the EEPROM can be erased and reprogrammed in-system.  Erasing and
programming is a slow operation, which may require unusual voltages and
higher power consumption.

A Flash ROM is pretty similar to an EEPROM.


The term "RAM" implies a randomly readable and writable memory, with
little or no penalty for writing.  This term is not applicable to a
device which has a slow write time or a limited number of write cycles.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P O Box 27-103, Wellington, New Zealand