Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!apple!mattd
From: mattd@Apple.COM (Matt Deatherage)
Newsgroups: comp.sys.apple2
Subject: Re: GRAPPLER C/MAC/GS COMPATIBILITY PROBLEM
Message-ID: <53072@apple.Apple.COM>
Date: 19 May 91 17:47:38 GMT
References: <9105161429.AA11984@apple.com>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 42


[Long question about the Grappler C/MAC/GS deleted]

Yes, it's true the Grappleer C/MAC/GS (the serial device that translates
ImageWriter II codes to codes for other printers) doesn't work with the new
5.0.3+ ImageWriter II driver.  I happened to share a table at lunch this
week (at the 1991 Worldwide Developer's Conference) with an engineer from
Orange Micro who told me why:

Their ROM is not unlimited and in certain cases they like to make speed
optimizations for common cases.  They made one a long time ago involving the
[Esc] F character sequence, which ostensibly moves the print head a given
amount horizontally without printing anything.

In all of the tests they ran, the only time they ever found this code being
sent was by the Macintosh ImageWriter driver, which was using it to skip
between gaps in characters in "draft" mode (the mode that uses the printer's
built-in characters).  So, since this was kind of slow when translated to
other printer's codes, they optimized this to change it to a number of space
characters (ASCII $20).  This made things a bunch faster.

Unfortunately for them, the new IW driver on 5.0.3+ does white-space
compression.  The old driver would print large areas of white space in a
single scan line by printing lots of graphics characters that fired no
printer pins.  The new driver saves time by using the [Esc] F sequence to
move the print head past the white space.  Since the Grappler box converts
this sequence to a series of ASCII spaces, which don't print in graphics
mode as white space, the printout is messed up and any printout with enough
white space to invoke the [Esc] F command will not work with the Grappler
box under the 5.0.3+ drivers.

Orange Micro knew about the problem but did not say if they intended to do
anything about it, since the 5.0.2 drivers work with their product and upgrade
costs are still pretty high for such a product.


-- 
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Matt Deatherage, Developer Technical  | The opinions expressed herein are
Support, Apple Computer, Inc.         | not those of Apple Computer, and
Personal mail only, please.  Thanks.  | shame on you for thinking otherwise.
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