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Path: utzoo!watmath!clyde!rutgers!seismo!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: net.periphs,net.micro.att
Subject: Buffer overflow in AT&T 4425 video display terminals
Message-ID: <1384@kitty.UUCP>
Date: Sun, 26-Oct-86 00:19:02 EST
Article-I.D.: kitty.1384
Posted: Sun Oct 26 00:19:02 1986
Date-Received: Sun, 26-Oct-86 07:40:27 EST
Organization: Recognition Research Corp., Clarence, NY
Lines: 25
Keywords: AT&T 4425, poor display throughput
Xref: watmath net.periphs:1260 net.micro.att:1662


	I finally got around to replacing the AT&T 4415 video display
terminals on our development 3B2 with 4425's, and relegated the 4415's
to other uses where their non-VT100 idiosyncracies did not matter.
	I just noticed something for the first time - which rather shocked
me (even though I had used 4425's previously).
	Since I was only running at 9,600 baud, and since the 4425 is supposed
to be an _improved_ terminal, I decided not to enable the DC1/DC3 mode.  No
problem at first - until I did a uulog, and watched the screen barf after
about 50 lines.  Any large text display (without attributes, even) causes the
screen to barf and lose characters, lines, etc. UNLESS the DC1/DC3 mode is
enabled.
	Why is this?!  These 4425's seem to have slower character throughput
than their predecessor 4415's.  I get FULL 9,600 baud throughput on other
VT100 clones, like the Datamedia DT-100. 
	In all fairness to AT&T, I find their terminals to be well-designed
and robust.  But WHY can't they achieve full 9,600 baud throughput like other
vendors?
	Can anyone tell me the _true_ character throughput for the 4425?
	Hello, AT&T/Teletype...

==>  Larry Lippman @ Recognition Research Corp., Clarence, New York
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