Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!rutgers!ucla-cs!zen!ucbvax!cbosgd!mandrill!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.sys.att
Subject: Re: Pathetic 3b1 terminal emulation speed
Message-ID: <900@neoucom.UUCP>
Date: 31 Dec 87 05:30:42 GMT
References: <890@neoucom.UUCP> <660@umbc3.UMD.EDU>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 39
Keywords: vi ^L and go get a cup of coffee while u wait
Summary: cu and s4 termcap / terminfo aren't enough

In article <660@umbc3.UMD.EDU>, alex@umbc3.UMD.EDU (Alex S. Crain) writes:
> and then uploaded the s4
> termcap to my VAX. The 3b1 makes a great terminal, and since we're running a
> very new version of emacs (18.4x) on the vax, my arrow keys even work!

As you might guess, I immediately put the s4 termcap and terminfo
up on the vax and went with cu, scapping ATE.  I did everything I
could to make sure performance of the 3b1 was maximized-- no user
agent, full window, nothing going on in the background.

Even at 1200 baud, try doing a tail -100 /etc/termcap on the vax
via cu.  If you are using an external modem, you'll notice that the
SD light starts blinking after about 1/2 screen of text scrolls.
What is happening is ^S/^Q flow control becuase teh 3b1 can't keep
up.  You'll certainly notice the slowness on a 2400+ baud modem or
a direct wire.

cu manages to get about 100 char/sec to the screen on receiving.
My point was that the serial port is capable of getting 550+
char/sec though at 9600 baud-- and that is including all the
handshaking that is done in the uucp g protocol.

3b native applications seem to be able to write around 500 char/sec
to the screen.  This would imply that if serail receive using full
CPU bandwidth is 550 char/sec and text render is 500 char/sec. That
with additional overhead added, cu should be able to get at least
200 char/sec to the screen.  It's only making half of that.

My real question is why the heck is ATE so s-l-o-w?  It would be
handy to use the vt100 emulation on a vms machine I call.

Moral of the story:  the 3b isn't meant to be a terminal emulator.
You should download/edit/upload.  Fortunately uucp makes this
relatively painless when talking to other Unix oriented machines.

Sorry if it sounds like I complain too much; I like the 3b none the
less.

Peace and happiness in the New Year,
Bill