Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!dogie.macc.wisc.edu!uwvax!per2!dag
From: dag@per2.UUCP (Daniel A. Glasser)
Newsgroups: comp.sys.atari.st
Subject: SLM804 from emulators...  Where the problem might lie.
Keywords: SLM804, Spectre128, SpectreGCR, PC Ditto, PC Speed, Emulators
Message-ID: <880@per2.UUCP>
Date: 29 Sep 89 20:05:02 GMT
Organization: Persoft Inc., Madison, WI
Lines: 57

Some people have gotten really angry over the lack of SLM804 support
in the various emulators running on the ST.  Although I can simpathize
with these people, I must take exception to the accusations that they
are making about the developers of these emulators.

The SLM804 is not a simple laser printer with its own imaging engine and
some sort of byte serial interface to the computer.  Support of the printer
requires the use of an in memory bitmap large enough to contain every pixel 
imaged on the page (actually, with double buffering and async programming,
the in memory bitmap can be smaller, but it is very difficult to program the
ST in that manner.)  This bitmap is then shipped to the printer via the DMA
port.

300dpi on an 8.5" x 11" page with an active area of 8" x 10.5" requires
2400 x 3150 pixels, or 300 bytes x 3150 scans, or 945,000 bytes.  In addition,
this in-memory bitmap must be written to with text and graphics properly
scaled to the output device.  Postscript output requires a postscript
interpreter, HP LaserJet output requires an HP PDL interpreter/emulator,
etc.  These interpreters and emulators take a lot of time and effort to
write, are hard to debug, and require considerable memory for internal
font and format storage beyond the page bitmap.

The emulators do not run under or along with TOS.  These programs must
either run as part of the emulator itself or under the emulator.
Add to that that the Atari DMA channel is very tricky to get right, and
the problem gets a little worse.  Add to that that this support must be
transparent to the application running under the emulator, so it must
behave as a common device in whatever environment is being emulated.

David Small and the people at AG would probably be willing to integrate
improved SLM804 support if someone were to offer them the required code
at a reasonable price in a useable form.  The support would probably be
limited to those machines with at least 2, and probably 4, megabytes.

Make whatever criterion you wish for your software selection.  Tell the
world about those choices that you make.  State a desire for features in
products that you find unusable because of the lack of those features.

Please don't keep whining about those "missing" features which were never
promised by the developers in the first place.  Would it be better if the
product were delayed by the additional months/years that it might take
for a single programmer or a small team to add those features which could
only be used by a small minority of what already is a small market?

Maybe someone could develop a program that runs under MAC-OS specific
to the ST which would do a 300dpi imagewriter (or DeskWriter) emulation
on an SLM804 and sell this as a separate item.

If we, as a user community, could have a little more understanding of
the technology that we demand and those who attempt to provide us with
it, morale (which is VERY important in this business) would be much
better.
-- 
 _____________________________________________________________________________
    Daniel A. Glasser                           One of those things that goes
    uwvax!per2!dag                              "BUMP!!!(ouch)" in the night. 
 ---Persoft, Inc.---------465 Science Drive-------Madison, WI 53711-----------