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From: culmer@eniac.seas.upenn.edu (Charles Culmer)
Newsgroups: comp.sys.apollo
Subject: Parallel port drives user nuts
Message-ID: <8937@netnews.upenn.edu>
Date: 19 Mar 89 02:24:45 GMT
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Reply-To: culmer@eniac.seas.upenn.edu (Charles Culmer)
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Organization: University of Pennsylvania
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I want to print display bitmaps pixel-for-pixel on 8.5 x 11 paper with
a dot-matrix printer.  (Walk through the bitmap scanlines and write a
file of printer graphics commands.  Then print the file.)

My serial printer (Integral P132) does only 84 dots per inch.  I also
have an Epson LQ-1500 (24 pins) that does 180 dots per inch.  However,
this printer has a parallel interface.

Apparently, there are some SPE system calls that aren't covered in the
manual "Installing and Programming the DOMAIN Series 3000 SPE Option".
I don't see them in /sys/ins/spe.ins.c, and there doesn't seem to be a
relevant help file.  (I have ordered the system call manuals.)

I don't believe any of the Apollo supplied device drivers is suitable,
and /sys/help/prsvr/device_drivers.hlp seems to be limited to help for
serial devices.

I don't really need a device driver.  I just want a simple I/O program
to write to the printer.  I played around with the sample program from
/domain_examples rewritten in C and using /lib/spe_pio_lib--

     ios_$open gives "device is read only" error.
     spe_$pio_set_mode gives "option is not initialized" error.

Can someone please help me out with these questions--

(1)  Is there a system call spe_$pio_init?  Parameters and types?

(2)  Do I need any other system calls to make this I/O program work?

(3)  Will I have any trouble sending every (char) i for 0 <= i <= 256?
     I think my serial port is trapping some control characters.  This
     isn't a problem with the 8 pin printer since it uses only 7 pins,
     so I can send characters 128 through 255, but the Epson needs all
     of the characters.

(4)  Why do parallel devices exist?

I have a final question about GPR--

(5)  What does the line_width parameter from gpr_$inq_bit_map_pointer
     mean?  Isn't it too large by a factor of 2?  This is suggested by
     the examples in "Programming with Domain Graphics Primitives" but
     not explained.

(I have a model 3000, monochrome 1280 x 1024, version 9.7.)

Thanks in advance.

Charles W. Culmer
culmer@eniac.seas.upenn.edu       Truth, justice, and the American way