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From: ecf_hap@jhunix.HCF.JHU.EDU (Andrew Poling)
Newsgroups: comp.sys.att
Subject: Re: 7300 and 9600 baud modems
Message-ID: <3381@jhunix.HCF.JHU.EDU>
Date: 22 Nov 89 22:12:09 GMT
References: <3311@convex.UUCP>
Reply-To: ecf_hap@jhunix.UUCP (Andrew Poling)
Followup-To: comp.sys.att
Distribution: usa
Organization: The Johns Hopkins University - HCF
Lines: 32

In article <3311@convex.UUCP> dale@convex.com (Dale Lancaster) writes:
>
>I am evaluating 9600 baud modems to attach to the serial
>port on my 7300 for terminal emulation.  I currently 
>have a Microcom QX/12K I am using on loan and it seems to me
>that I am not getting 9600 baud throughput even though all
>the status indicators say such.  Can I assume that the 7300
>can (using cu) keep up with 9600 baud on the serial line?
>I would think any decent computer including my Apple IIE
>could handle this.  

Not true.  My Apple II+ dropped characters at 4800 baud.  And that was
straight throughput - no terminal emulator.  What really killed it was/were
carriage-returns.

>My reason for doubting is that a full screen update takes on order
>of 5-6 seconds, I am used to about 2-3 seconds when running full
>bore on a direct connect terminal at work, running a true 9600 baud.
>Also, I realize that the Microcom is not a real 9600 baud modem
>(it uses 3 to 1 data compression on a 4000 baud interface), but
>before I start trying other modems, I need to verify that the 7300
>isn't the real bottle neck.

I have never witnessed my UNIXpc (3b1 with 2.5M/40M and plenty of active
drivers including ethernet, usually 30-35 proccesses running) handling 9600
baud incoming without flow control coming into play.  

But there may be other factors.  Perhaps the termcap you are using calls for
excessive padding on certain events.  In other words, the change in terminal
types may cause a difference in apparent transfer rate.

-Andy