Path: utzoo!attcan!ncrcan!ziebmef!mcp
From: mcp@ziebmef.mef.org (Marc Plumb)
Newsgroups: comp.sys.amiga
Subject: Re: printer question
Summary: Fixing double-spacing
Message-ID: <1989Sep5.230820.14106@ziebmef.mef.org>
Date: 6 Sep 89 03:08:18 GMT
References: <5234@alvin.mcnc.org>
Reply-To: mcp@ziebmef.mef.org (Marc Plumb)
Distribution: usa
Organization: Ziebmef Public Access Unix, Toronto, Ontario
Lines: 35

> [Printing to prt: double-spaces; par: doesn't.  Help!]

This is the classic symptom of the CR/LF confusion.  When ASCII was
defined in 1966, it was an "Information Interchyange" code, not
really designed to be an internal standard (as it is universally today,
except for some older machines and IBM Hulking Giants), and a few odd
choices were made, particularly in the prolixity of control codes
offered.  The commitee wanted separate codes for horizontal and
vertical cursor motion and thus came up with CR (to move the print head
to the left margin - no CRT's in those days!) and LF (to move the
print head down a line, or the paper up one, whatever).  So
printers were designed to do this, and all was well until all the
8-bit computers (Apple, PET, Atari, TRS-80 etc.) decided that two
characters to say "new line" was stupid, so they started using just CR.
(The ASCII standard encouraged the use of LF, to be called NL, for a
single line terminator, since it would leave CR LF doing The Right Thing.
Unix and Amy follow this standard.)

Printers then added a DIP switch to decide whether CR included a line feed
or not, and many factory defaults became "yes."  Of course, if you had
slightly smarter software that followed the ASCII standard, it would
send "CR LF" and get two line feeds (one implicit in the CR, one
explicit in the LF) for the price of one, causing double-spacing
bugs as you're seeing.  On your Amiga, prt: is ther smarter software
and par: is the dumb copy-bytes stuff, and you're getting pretty much
that problem.

The solution is either to tell preferences that your printer auto-line-feeds
on CR, or set the printer not to auto-line-feed.  The latter is slightly
preferable, as it gives a bit more flexibility, but either will solve
your problem.

Hope this helps, and the meat didn't get lost in the history.
-- 
	-Colin Plumb