A couple of months ago I briefly unplugged my faithfull old HP Laserjet 4
which I've had since about 1993 because I couldn't find anywhere else handy
to plug my electric shaver charger into. On plugging the printer back in
later in the day it was dead as a dodo. I got as far as checking the fuse in
the plug with my multimeter but the thought of pulling the printer to bits
was too much to bear and not really needing to use it I left it alone until
today when I finally decided I really ought to do something about it.

No idea what had happened but after trying some deeply technical measures
like hitting it several times and opening and shutting all the flaps and
doors in case a microswitch wasn't working it burst into life again. It then
did the most extraordinary thing. After running its little self tests,
flashing a few lights on and off and booting up fully it printed out a sales
invoice of mine from 1995!!!!!

I wasn't even running the accounts software at the time and haven't done for
weeks so it was nothing to do with what was on the pc. I can't even remember
what pc I would have owned back then to have composed that invoice on in the
first place. Some old Intel 386 running Dos long since chucked out I
imagine. I clearly remember still only using Windows 3.1 (i.e. Dos
basically) on a 486 when I first got on the internet in 1998 and didn't even
get round to trying 'proper' Windows i.e. 95 for another year or so when AOL
stopped supporting 3.1.

So HTF did a laser printer have stored inside it the details of a 13 year
old sales invoice which I'm absolutely sure I haven't opened on the pc since
then or at least not for a very very long time? I still remember the
customer but I've had no reason to look at that invoice since then and
clearly none at all to want it printed out again. I didn't think printers
stored anything after they'd finished printing them out but god knows what
lurks inside this one now. I'm totally gobsmacked.
--
Dave Baker

On plugging the printer back in later in the day it was dead as a dodo.

IIRC HP have a "secret" counter in the machine that will cause it to
"break" after a certain amount of use - it's possible that this may
extend to failing after a certain lifespan.

Don't know what happened over the old invoice appearing, but another
secret "feature" the use of tiny dots on the page, so as to provide an
audit trail for anyone who might want to know the serial number, date
and time of a print to perhaps defeat faked documents. Colour printers
tend to use yellow dots, which appear black under a blue light.

http://www.eff.org/issues/printers
http://w2.eff.org/Privacy/printers/docucolor/

Dave Baker wrote:

A couple of months ago I briefly unplugged my faithfull old HP Laserjet 4

Not a high end version with internal hard drive by any chance?

flashing a few lights on and off and booting up fully it printed out a sales
invoice of mine from 1995!!!!!

The only other obvious cause would be something sat in the spool queue,
possibly printed by accident, that was printed some time when the
printer was offline.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
et...
Dave Baker wrote:

A couple of months ago I briefly unplugged my faithfull old HP Laserjet 4

Not a high end version with internal hard drive by any chance?

In a 1992 HP4L monochrome printer? Hardly.

http://en.wikipedia.org/wiki/HP_LaserJet_4



flashing a few lights on and off and booting up fully it printed out a
sales invoice of mine from 1995!!!!!

The only other obvious cause would be something sat in the spool queue,
possibly printed by accident, that was printed some time when the printer
was offline.

I suppose if I'd managed to open a 13 year old invoice by mistake, select
print, select the various print options, press go and then forget all of
that it's a possibility. Maybe the pc, which admittedly does have a mind of
its own, could have done it. It crashes at regular intervals but whether any
of those could select to print a 13 year old invoice I couldn't say.
--
Dave Baker

On Wed, 3 Sep 2008 22:49:51 UTC, Colin Wilson
o.uk wrote:

IIRC HP have a "secret" counter in the machine that will cause it to
"break" after a certain amount of use - it's possible that this may
extend to failing after a certain lifespan.

Don't know what happened over the old invoice appearing, but another
secret "feature" the use of tiny dots on the page, so as to provide an
audit trail for anyone who might want to know the serial number, date
and time of a print to perhaps defeat faked documents.

Not on a 1993 printer!

I'd expect it to be something stuck in the spool queue...the printer has
very little memory by modern standards...max for a LJ4 is about 18MB I
believe.

If you have any more trouble let me know. As a hobby, I've played with
the innards of these (and LJ4+) quite a bit.
--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

Dave Baker wrote:
"John Rumm" wrote in message
et...
Dave Baker wrote:

A couple of months ago I briefly unplugged my faithfull old HP Laserjet 4
Not a high end version with internal hard drive by any chance?

In a 1992 HP4L monochrome printer? Hardly.

some of the posher versions of those did have a hard drive option.

http://en.wikipedia.org/wiki/HP_LaserJet_4

The 4V in '94 if that is correct.... I had a feeling it was also
available on the earlier ones, but that might be my memory playing tricks.

flashing a few lights on and off and booting up fully it printed out a
sales invoice of mine from 1995!!!!!
The only other obvious cause would be something sat in the spool queue,
possibly printed by accident, that was printed some time when the printer
was offline.

I suppose if I'd managed to open a 13 year old invoice by mistake, select
print, select the various print options, press go and then forget all of
that it's a possibility. Maybe the pc, which admittedly does have a mind of
its own, could have done it. It crashes at regular intervals but whether any
of those could select to print a 13 year old invoice I couldn't say.

Is there an application associated with the invoice file type? Makes it
slightly easier to open by accident if all you need do is click it.

Other than that, not sure what else to suggest!



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Dave Baker" wrote in message
...
A couple of months ago I briefly unplugged my faithfull old HP Laserjet 4
which I've had since about 1993 because I couldn't find anywhere else handy
to plug my electric shaver charger into. On plugging the printer back in
later in the day it was dead as a dodo. I got as far as checking the fuse
in the plug with my multimeter but the thought of pulling the printer to
bits was too much to bear and not really needing to use it I left it alone
until today when I finally decided I really ought to do something about it.

No idea what had happened but after trying some deeply technical measures
like hitting it several times and opening and shutting all the flaps and
doors in case a microswitch wasn't working it burst into life again. It
then did the most extraordinary thing. After running its little self
tests, flashing a few lights on and off and booting up fully it printed
out a sales invoice of mine from 1995!!!!!

I wasn't even running the accounts software at the time and haven't done
for weeks so it was nothing to do with what was on the pc. I can't even
remember what pc I would have owned back then to have composed that
invoice on in the first place. Some old Intel 386 running Dos long since
chucked out I imagine. I clearly remember still only using Windows 3.1
(i.e. Dos basically) on a 486 when I first got on the internet in 1998 and
didn't even get round to trying 'proper' Windows i.e. 95 for another year
or so when AOL stopped supporting 3.1.

So HTF did a laser printer have stored inside it the details of a 13 year
old sales invoice which I'm absolutely sure I haven't opened on the pc
since then or at least not for a very very long time? I still remember the
customer but I've had no reason to look at that invoice since then and
clearly none at all to want it printed out again. I didn't think printers
stored anything after they'd finished printing them out but god knows what
lurks inside this one now. I'm totally gobsmacked.

Was it a draft print of the invoice which you later recycled and put back in
the draft printer tray (if it has one)?