[comp.sys.atari.st] Okidata Microline 390 and the Atari ST

SKOLODZIESKI@VAXB.STEVENS-TECH.EDU (09/22/89)

	I have been having a problem getting my Okidata 390 to print graphics 
correctly with my 1040 ST. The problem seems to manifest itself most frequently
in the 24 pin emulation mode. The problem is being that 3 bytes (24 bits) of 
data are being sent to the printer to print a single column of dots. At some 
random time, so it seems to me at least, one of the 3 bytes gets droped and 
the entire rest of the line is screwed up, beause of byte misalignment. Does
anyone have the same problem or know of a fix. 

						Scott J. Kolodzieski 
						Stevens Institute of Tech.

					"skolodzieski@vaxc.stevens-tech.edu"
------------

greg@sj.ate.slb.com (Greg Wageman) (09/23/89)

Opinions expressed are the responsibility of the author.

In article <89821142951.20206e76.SKOLODZIESKI> SKOLODZIESKI@VAXB.STEVENS-TECH.EDU writes:
>
>	I have been having a problem getting my Okidata 390 to print graphics 
>correctly with my 1040 ST. The problem seems to manifest itself most frequently
>in the 24 pin emulation mode. The problem is being that 3 bytes (24 bits) of 
>data are being sent to the printer to print a single column of dots. At some 
>random time, so it seems to me at least, one of the 3 bytes gets droped and 
>the entire rest of the line is screwed up, beause of byte misalignment. Does
>anyone have the same problem or know of a fix. 

I have seen this with my Okimate 20, when printing Spectrum pictures
in color.  I believe it is another manifestation of the sound chip's
inability to consistantly drive high loads on the printer port.  One
solution would be to implement the external buffering scheme that was
posted here for people with DeskJet printers; in my case, I acquired
an external printer buffer box, which the Atari seems to have no
difficulty driving, and which seems to be able to drive the Okimate
just fine.  No more glitches.

Another solution would be to use the serial port for printing, but if
you've got a modem (who doesn't?) that would require either switching
cables (yuk! phui!), or a switchbox ($$).

Buffer your printer port.

Copyright 1989 Greg Wageman	DOMAIN: greg@sj.ate.slb.com
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