OT, printer weirdness

[Dave Baker]

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.

[Colin Wilson]

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.

[John Rumm]

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

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.

[Dave Baker]

In a 1992 HP4L monochrome printer? Hardly.

>> flashing a few lights on and off and booting up fully it printed out a

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.

[Bob Eager]

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.

[John Rumm]

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

available on the earlier ones, but that might be my memory playing tricks.

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!

[Grumps]

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