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From: bryan@mothra.cs.utexas.edu (Bryan Bayerdorffer)
Newsgroups: comp.sys.amiga
Subject: mysteries of printer drivers
Message-ID: <9312@ut-sally.UUCP>
Date: Mon, 19-Oct-87 02:26:44 EDT
Article-I.D.: ut-sally.9312
Posted: Mon Oct 19 02:26:44 1987
Date-Received: Tue, 20-Oct-87 00:43:24 EDT
Sender: news@ut-sally.UUCP
Reply-To: bryan@mothra.cs.utexas.edu (Bryan Bayerdorffer)
Organization: Spam Detection & Removal Squad, Austin, TX
Lines: 31
Keywords: printer driver code device dependent weirdnesses
Summary: Would someone please explain the *&^$@! init.asm
Spam-Content: Negligible



	See, I have this IDS 460G (vintage 1980, back when 2K was LOTS of 
printer buffer), and I'm trying to write a driver for it.  I'm also working 
with the OLD RKM--the one published by Commodore, not Addison Wesley.  My
gratitude would be boundless if someone could answer the following questions
about the example drivers, since the explanation in the RKM is a bit sparse:

	1. Why do the various init.asm files open all those libraries?  As far
	   as I can see, none of the driver code references any library 
	   functions.  Specifically, why do the inits for the diablo, hp plus,
	   and okimate20 all open graphics.library, dos.library, and intuition.
	   library, while the epson init only opens graphics.library?
	
	2. Why does printertag.asm XREF _PrinterSegmentData, when this isn't
	   referenced anywhere in the file?  I'm just wondering if I'm missing
	   something deep here.

	And no, I can't use PrtDrvGen (author's name escapes me) to build the
driver, because this printer wants any 0x03s that it gets during a graphics
dump duplicated, because this is the command escape character.  PrtDrvGen 
doesn't support this, and it also means I have to make the buffer twice as long
as usually necessary, to support a potential stream of all 03s.  Sigh.


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