Working my way through my mail backwards, Bruce wrote last week:

> The printer on our Micro3000, a 10-year-old LaserJet IIP (that's a model
>  number, not an emoticon) gave up the ghost last week. Since that's the
>  printer that does my paycheck, among other things, there was a certain
>  urgency in seeing to its replacement, and I bought a used LaserJet 4siMX
>  (with duplexer) to take its place. Duplexers are necessary these days
>  since nobody ships paper manuals any more, and this particular 4SiMX has
>  both a serial and a JetDirect interface so it could comfortably bridge 14
>  years of hardware technology.
>
>  The printer works fine, but has an oddity: When set for "Duplex=NO" on
>  the front panel, the printer can't be forced into duplex mode (at least,
>  not from PostScript). However, when set for "Duplex=YES", the printer
>  normally duplexes but can be told NOT to duplex. This seems sufficiently
>  backwards that I must be missing some important setting. Can anyone help?
>  It's annoying because this way, I either have to set/clear duplexing
>  manually or put up with duplexed checks, which the bank does not like.

We've never had any problem doing what you want to do, Bruce.

I've included some HP3000/QueryCalc-generated PostScript code below. The only
thing that you can't see on the code is the Cntrl+D's (the Apple extension to
PS that is in all PostScript printers, that causes a printer job reset,
flushing any existing PS fragments so that you can be sure that you are
working with a clean PS interpreter) which we pre- and postpend to all PS
code that we generate.

=======================================

^D
%^PS-Adobe-3.1
%%Creator: AICS Research, Inc.
%%DocumentFonts: Helvetica
%%BoundingBox: 0 0 612 792
%%Pages: (atend)
%%EndComments
statusdict begin
true setduplexmode
end
/vmstate save def
/$aics 210 dict def
$aics begin
/cellwidth 72 def
/rightshow {dup stringwidth pop cellwidth exch sub 0 rmoveto show} def
/rjshow {dup stringwidth pop neg 0 rmoveto show} def
/centershow {dup stringwidth pop cellwidth exch sub 2 div 0 rmoveto show} def
/Courier-Bold findfont 9 scalefont setfont 0 setgray
/Times-Roman findfont 11 scalefont setfont 0 setgray
save
/Times-Roman findfont 11 scalefont setfont 0 setgray
168 684 moveto
/cellwidth 72 def
(Bruce Toback) show
showpage
restore
end
vmstate restore
%%Trailer
%%Pages: 1
^D

========================================

Notice the command inside the statusdict definition: "true setduplexmode".
This is one of the HP-invented PS commands that appeared in LaserJet III
series printers. This and other similar commands are fully documented in the
LaserJet IIID manual.

Adobe came along later an defined their media commands -- which are much more
complicated -- to do the same things. HP now only documents the Adobe media
commands, but every HP printer I've played with appears to still support the
old HP-only commands, which they now call "compatibility mode." I've yet to
find an HP printer on which they don't work, so I still use them
preferentially when I'm sure that I'm using an HP printer.

I've never had any trouble with these commands not overriding the panel
settings.

Wirt Atmar