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From: jer@peora.UUCP (J. Eric Roskos)
Newsgroups: net.micro.mac
Subject: Re: Imagewriter bi-directional printing
Message-ID: <1033@peora.UUCP>
Date: Fri, 7-Jun-85 09:23:04 EDT
Article-I.D.: peora.1033
Posted: Fri Jun  7 09:23:04 1985
Date-Received: Sat, 8-Jun-85 03:57:20 EDT
References: <172@mb2c.UUCP>
Organization: Perkin-Elmer SDC, Orlando, Fl.
Lines: 24

Well, having written a program awhile back to make the IBM PC simulate the
Mac's font-printing (using TeX fonts), I can make a good guess.

The C. Itoh printers don't have perfect back-and-forth registration.  I.e.,
when you print forward the dots come in a slightly different place from when
you print backwards.  There's a potentiometer that is supposed to adjust
this, but it doesn't completely eliminate the problem in graphics mode.

For high-resolution mode, this slight offset would actually be a help.  It
causes the overstruck dots to be shifted slightly, filling in the gaps that
would be otherwise left.  But Standard mode doesn't overstrike like that; I
suspect if it printed forward-and-backward, the characters printed would
come out with noticeably shifted bands of dots (e.g., the top half of a
character might be offset to the right or left from the bottom half).

In draft mode, it doesn't matter, since you are just using the internal,
one-pass characters.
-- 
Full-Name:  J. Eric Roskos
UUCP:       ..!{decvax,ucbvax,ihnp4}!vax135!petsd!peora!jer
US Mail:    MS 795; Perkin-Elmer SDC;
	    2486 Sand Lake Road, Orlando, FL 32809-7642

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