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From: muller@sdcc7.ucsd.EDU (Keith Muller)
Newsgroups: net.unix
Subject: Re: 4.3 dropping characters ?
Message-ID: <542@sdcc7.ucsd.EDU>
Date: Tue, 7-Oct-86 04:44:22 EDT
Article-I.D.: sdcc7.542
Posted: Tue Oct  7 04:44:22 1986
Date-Received: Wed, 8-Oct-86 07:10:59 EDT
References: <323@uwmacc.UUCP>
Distribution: net
Organization: University of California, San Diego
Lines: 20

In article <323@uwmacc.UUCP>, edwards@uwmacc.UUCP (mark edwards) writes:
> 
>    Has anyone else experienced dropped characters on their screens.
> 
>    We have emulex dmfs. It seems either the first character of a line
>    or the last character of a line get dropped occasionally.

This is because the UCB dmf driver expects that at the end of a dma
output the dma address register contains the dma start address + the
dma character count. It uses this to determine hown many characters
ndflush is to be called with. emulex and other non dec dmf's unibus
word align this register so that when odd count dma's are performed
one character too many is flushed.
There is also a flow control problem that causes some lines to be
output more than once. I posted the fixes to both problems once before,
but you can send mail me if you cant get them.
	Keith Muller
	University of California, San Diego
	muller@nprdc.ARPA
	muller@sdcsvax.ucsd.EDU