From: mjp3783@ritvax.isc.rit.edu
Subject: Re: How do I get LIGHTNING on my SupraFAX?
Reply-To: mjp3783@ritvax.isc.rit.edu
Organization: Rochester Institute of Technology
Distribution: comp
Date: Fri, 24 Jul 1992 02:00:20 GMT

In article <1992Jul22.192418.6462@wam.umd.edu>, walrus@wam.umd.edu (Udo K Schuermann) writes:
>Well, here's my bit of advise on how to maximize your throughput with high
>speed modems.  I'm basing this on my SupraFAX V.32bis modem but it should
>apply to similar modems as well:
>
>1. Read the documentation on your modem to let it select the best connect
    ^^^^^^^^^^^^^^^^^^^^^^
    always RTFM! ;-D      
>   speed.  There are a lot of options available but loading the factory-
>   settings #2 (at&f2, I believe) has worked quite well for me.
>
>2. Avoid XON/XOFF.  Set your serial-preferences to CTS/RTS, which allows
>   the modem and the computer to do handshaking via dedicated hardware
>   lines.
>
>3. Use the highest speed between your modem and your computer that doesn't
>   cause you loss of data.  Rough rule of thumb:  KS1.3/68000: 19200 baud.
>   KS2.04/68000: double that; accellerated machines: use 57600.
>
>   The modem will stop your computer via CTS/RTS if your computer goes too
>   fast, and if stuff comes in from the other system slower than your
>   actual connection between modem and computer, then your computer will
>   simply not get things as quickly as it is able to.
>
>4. Video modes:  watch the modem receive light.  If the light goes off and
>   your screen is still scrolling text, then your display is lagging behind.
>   Your choices are to increase the pre-scroll (VLT has it, I don't know
>   about other software), reduce the number of bitplanes/colors of your
>   terminal.
>
>5. Protocol: use streaming protocols, such as zmodem.  Zmodem transmits
>   without having to stop until the other end complains because of errors
>   or whatever.  This means that there is no "transmit-ACK/NAK" cycle and
>   transfer is as fast as reading and writing the information to disk
>   allows.  I don't know how Ymodem-G and other protocols work, but I
>   suspect it's more a features thing from there on, rather than
>   performance.

Use Ymodem-g - it is similar to zmodem, but has no error recovery. It is a bit
faster and if there is an error, (under JR-Comm, at least) you can recover
using zmodem!


>
>
>Miscellaneous tidbits:
>
>Because of error-correction protocols being handled in hardware,
>transmission errors are less frequent with V.42bis/MNP modems.
>
>I run VLT at a priority of 2 to make sure the process is never blocked by
>any of the things that *I* do.  This reduces the chance of more stuff
>coming in on the modem side than the computer can swallow at once.

If you don't want to multi-task, set priority to that of input.handler.

>
>
>I hope the above is helpful to others who are curious or wondering how to
>get the most out of their fast modem.  If anyone has anything to add to
>this, please let us hear it.
>
> ._.  Udo Schuermann     "If I went around calling myself emperor just because
> ( )  walrus@wam.umd.edu  some moistened bint lobbed a scimitar at me, they'd
> Seeking virtual memory   put me away!"         -- Monty Python's "Holy Grail"
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| Michael Phipps == mjp3783@ritvax.isc.rit.edu (R.I.T.)            |
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