You're right, you can DESTROY data recorded on an EPROM. You have to set
about to do that, however, and I know few archives where that's likely to be
tolerated.
If you put floppy diskettes on the shelf and wait 20 years, you'll see
what's left of your archive.
Dick
----- Original Message -----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, May 30, 2000 5:52 PM
Subject: Re: Defining Disk Image Dump Standard
> >
> > You don't get it, do you?
>
> No, _You_ don't get it.
>
> We're not talking about making an archive _on_ floppy disks. We're
> talking about defining a format for a file to be used to store the
> contents of floppy disks.
>
> This file can be stored on just about anything. Magnetic disks, magnetic
> tape, multiple reels of paper tape, EPROMs, Bubble memory, you name it.
>
> The idea is that floppy disks (that's real floppy disks) from classic
> computers (which, like it or not are what this list is about :-)) can
> then be archived on something a little easier to preserve and a little
> easier to transfer around the world than the physical disks.
>
> > environmental conditions. OTP EPROMS are pretty stabile, however, and
> > they're VERY small.
>
> Rubbish!.
>
> I am _not_ going to trust my data to charges stored on the floating gates
> of some chip. No way. Even the manufacturers quote data lifetimes of a
> few 10s of years at most. That is not archival storage. Nor are EPROMs
> particularly robust -- they can be damaged by static, head, misapplied
> voltages, etc.
>
> I back up EPROMs to other media, not the reverse...
>
>
> >
> > If you're serious about creating an archive. It needs to be permanent,
so
> > it's essentially requisite that the media be write-once. I'd say you're
>
> Actually, OTP EPROMs are not write-once. You can write them as many times
> as you like. The only thing is you can only change a '1' into a '0', and
> never the reverse. So you could 'erase' the archive (simply fill the
> EPROM with 0s). Or corrupt it (flip a few odd 1's to 0's).
>
> FWIW, the Psion Organiser (an early UK-made PDA) had plug-in EPROM
> cartridges. These were used as file storage devices. A file could be
> 'deleted' by setting a bit in its header to 0, whereupon the system would
> no longer find the file, but obviously it would still take up space on
> the EPROM. The Datapak (EPROM module) could be 'reformatted' in a special
> formatter, which was nothing more than a UV-eraser.
>
> > better off with an OTP EPROM. Hardware to create them is dirt-simple to
> > create, eraseable/rewritable equivalents are readily available, and even
if
> > the OTP's (very inexpensive, by the way) become scarce, there will still
be
> > rewritables available which can be write protected by removing the VPP
or
> > program pin. Use those and you'll have a real archive. What's more,
there
>
> Incidentally, a lot of EPROMs don't like having Vpp floating, they want
> it tied to Vcc (normally). Ditto for PGM/
>
> -tony
>
Received on Tue May 30 2000 - 19:28:42 BST