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From: sl@van-bc.UUCP (Stuart Lynne)
Newsgroups: comp.sources.d,comp.terminals
Subject: Re: VT100's keeping up at high baud rates
Message-ID: <837@van-bc.UUCP>
Date: Mon, 15-Jun-87 22:41:13 EDT
Article-I.D.: van-bc.837
Posted: Mon Jun 15 22:41:13 1987
Date-Received: Sun, 21-Jun-87 06:10:39 EDT
References: <1149@carthage.swatsun.UUCP> <8601@tekecs.TEK.COM>
Reply-To: sl@van-bc.UUCP (Stuart Lynne)
Organization: Public Access Network, Vancouver, BC.
Lines: 42
Xref: mnetor comp.sources.d:849 comp.terminals:311

In article <4101@teddy.UUCP> jpn@teddy.UUCP (John P. Nelson) writes:
>>> - Some (all?) PC/clones cannot keep up with speeds > 4800 baud in the VT100
>>> - terminal emulator
>>> 
>>Heck, even the VT100 "emulation" inside a bona-fide _V_T_1_0_0 can't
>>keep up at speeds of more than 4800 baud.
>>
>
>I once did some benchmarking that you all might find interesting.  I
>wrote a program which did nothing but fill a 80x24 screen with blanks
>several times, to time the terminal throughput (admittedly, without
>scrolling, since that was not part of our requirement).  The only

>Anyway, true VT100's had a throughput just over 9600 baud.  VT101's had
>a throughput of only 4800!!!!  VT220's could go a sustained 19200 baud!
>

The problem with VT100 is mainly with scrolling!

From page 79 of the VT100 User Guide (2nd Edition, Jan '79):

	"Fill characters are required to keep the VT100 synchonized with the
	host computer when the XON/XOFF control codes are not used...."

The following is gleaned from table C-1 on the same page:

			NEL, IND, LF, RI	NEL, IND, LF,RI
	Speed		Smooth Scolling		Jump Scrolling
	19200		384			60
	9600		192			30
	4800		96			15
	2400		48			11
	1200		24			7
	300		6			1

	NEL		Next Line
	RI		Reverse Index
	IND		Index


-- 
Stuart Lynne	ihnp4!alberta!ubc-vision!van-bc!sl     Vancouver,BC,604-937-7532