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From: minow@mountn.dec.com (Martin Minow)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Serial print ?
Message-ID: <1331@mountn.dec.com>
Date: 4 Feb 90 02:42:13 GMT
References: <227700053@uxa.cso.uiuc.edu>
Reply-To: minow@thundr.enet.dec.com (Martin Minow)
Organization: Digital Equipment Corporation
Lines: 31

In article <227700053@uxa.cso.uiuc.edu> ews00461@uxa.cso.uiuc.edu describes
a problem dumping a text file to an attached serial printer at 9600 Baud.
The printer "beeps" and garbage is printed.

I would guess that the printer is trying to XOFF the Macintosh and the
Mac isn't responding to the XOFF (or is responding too slowly).  You might
try looking at the serial line setup parameters (SerHShake on IM II-251).
Off the top of my head, you should set the SerHShake parameter block to:
	fXOn	true -- DECwriter can XOFF host.
	fCTS	false (but check the DECwriter manual and cabling)
	xON	('Q' & 0x1F)
	xOff	('S' & 0x1F)
	errs	0
	evts	0
	fInX	false -- Mac can't XOFF the DECwriter
	null	0

Note: fCTS requires hardware/firmware support in the DECwriter and a cable
that passes the correct signals.  I have no idea if that's possible.
Also, I *think* I have fXOn and fInX correct: you want the Mac to react
to XOFF/XON sent from the DECwriter, but don't want the Mac to send these.

Also, if the DECwriter engineers used the same algorithm I used for DECtalk,
it should be able to accept about 1/4 second worth of text after sending
an XOFF.

Hope this helps.

Martin Minow
minow@thundr.enet.dec.com
The above does not represent the position of Digital Equipment Corporation