I think you should consider using a floppy drive because -

1.    Cheap initially
2.    Media cheap and swappable easily.
3.    Swapped out media may be sent to other people and taken offsite
for backup security.
4.    Once you've done it successfully you can show me how you did it
so that I don't have to do the work :-)

The priority which these come in is not necessarily numerical :_)

Seriously though - apart from the "power it from the DB25 socket" a
floppy may be a good idea.
Can't be *too* hard although the PICs limited memory may be a
challenge. Long long lo... ago I wrote (actually, modified) a floppy
disk controller using a 1771 AFAIR connected to a 6802. A modern
all-in-1-chip controller (and possibly a FIFO?) may be all it takes.

Then of course there's an IDE drive - I understand (BIMBW *) that you
can write to  these as slow as you like with internal buffer looking
after write speed considerations.


I've oft thought that an RS232 serial connected floppy could be a
very useful device, even in these Flash capable days. Once 2MB Flash
plug in modules get down to $NZ4.50 for a box of 10 the attraction of
the floppy may pale.


Russell McMahon

* - But,IMayBeWrong!.

From: James Cameron <quozl@US.NETREK.ORG>

>Want a recommendation for a serial EEPROM or other non-volatile
memory
>in the 256k to 4Mb range to which a 12C509 may speak.
>For an antique computer, an 80C85 based Tandy 100/102/200 laptop, I
have
>volunteered to a group of users on the 'net to investigate the
>construction of a simple device to act as offline storage.
>
>I had envisaged a 12C509 talking to a serial EEPROM.
>
>The interface to the laptop would be via the RS-232-like serial
port,
>which I can program under software control to all sorts of baud
rates.
>An 81C55 timer is used as the baud rate source.
>
>Ideally I'd want to fit the two chips into a DB25 backshell; though
they
>are getting small nowadays, these backshells.
>
>I expect to run the device from power available from the DB25
socket,
>i.e. parasitic with "shocking" diodes, now that I understand why.
;-)