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From: rjn@hpfcso.HP.COM (Bob Niland)
Newsgroups: comp.sys.hp
Subject: Re: Printer Eavesdropper
Message-ID: <7370031@hpfcso.HP.COM>
Date: 13 Nov 89 03:35:09 GMT
References: <330025@vantage.UUCP>
Organization: Hewlett-Packard, Fort Collins, CO, USA
Lines: 18

re: "A user claims to have heard of a "box" that allows one to capture
     print images sent to a printer."

If you mean capture on paper, then most HP HP-IB printers can be set to
either Listen-Always or merely to the same bus address as the target
printer.  Put the eavesdrop printer in Display-Functions mode (<ESC>Y) so as
to print, rather than act on, control characters in the data stream.

If you mean capture in machine-readable form, many HP host HP-IB interfaces
can be set to non-system-controller mode, and via the appropriate I/O
libraries, programmed to act as devices.  This is fairly straightforward on
Series 300 BASIC/WS, for example, using either the built-in or 98624A HP-IB
interface.  It can also be done in HP-UX DIL.  Set the interface to the same
address as the target device.  Read bytes.

Regards,                                              Hewlett-Packard
Bob Niland      rjn%hpfcrjn@hplabs.HP.COM             3404 East Harmony Road
                UUCP: [hplabs|hpfcse]!hpfcla!rjn      Ft Collins CO 80525-9599