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From: richard@pegasus.com (Richard Foulk)
Newsgroups: comp.lang.postscript
Subject: Re: secret fun things to do with HP LJ III with PostScript?
Message-ID: <1991Apr16.152454.6551@pegasus.com>
Date: 16 Apr 91 15:24:54 GMT
References: <31955@usc>
Organization: Pegasus,  Honolulu
Lines: 59

>> A few months back Chris Torek posted an article pointing out some nifty
>> undocumented features of the HP LJ II with a PostScript cartridge
>> installed.
> 
>Can anyone mail me a copy of the above-referenced article?  Thanks!

A number of people have asked me for this by mail too, so here it is:


| From: torek@horse.ee.lbl.gov (Chris Torek)
| Newsgroups: comp.lang.postscript
| Subject: secret fun things to do with HP LJ II with PostScript
| Message-ID: <9371@dog.ee.lbl.gov>
| Date: 30 Jan 91 08:16:02 GMT
| Organization: Lawrence Berkeley Laboratory, Berkeley
| Lines: 39
| 
| The HP LaserJet II has a front panel.  The PostScript interpreter
| can write to the front panel, but the method is secret.  (Almost
| everything interesting is secret, e.g., the secret way to switch
| between hardware and software flow control---just add or subtract
| 4 to/from the last parameter to setscc{batch,interactive}---but
| that is just HP not documenting things.)
| 
| Anyway, under the executive, to display `foo' in the front panel,
| type (note, PS> is the printer's prompt):
| 
| 	PS>serverdict begin
| 	PS>$frontpaneldict begin
| 	PS>switchexec 0 get 29 get 13 get begin
| 	PS>/fpjobstate (foo) def
| 	PS>end end end
| 
| In batch mode, the command sequence
| 
| 	serverdict begin $frontpaneldict begin
| 	switchexec 0 get 29 get 13 get begin
| 	(hello) setdisplay 2000 pause
| 	end end end
| 
| should put `hello' on the display for 2 seconds.  (It then reverts to
| whatever is in fpjobstate, I think.)
| 
| Note: use great caution here, as you have full control over the front
| panel buttons.  You can make these execute arbitrary PostScript code.
| 
| How do you find out more?
| 
| Use a recursive dictionary displayer to march through `serverdict'.
| All sorts of goodies spill out.  Many of the important dictionaries
| (such as the one containing fpjobstate and setdisplay) have no name
| and must be obtained with `get' sequences like the above.  This is
| annoying, but there is not much you can do about it.
| --
| In-Real-Life: Chris Torek, Lawrence Berkeley Lab EE div (+1 415 xxx xxxx)
| Berkeley, CA		Domain:	torek@ee.lbl.gov
| 
-- 
Richard Foulk		richard@pegasus.com