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- From: walrus@wam.umd.edu (Udo K Schuermann)
- Newsgroups: comp.sys.amiga.datacomm,comp.sys.amiga.hardware
- Subject: Re: How do I get LIGHTNING on my SupraFAX?
- Message-ID: <1992Jul22.192418.6462@wam.umd.edu>
- Date: 22 Jul 92 19:24:18 GMT
- References: <1992Jul22.085505.13897@vax5.cit.cornell.edu>
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- Distribution: comp
- Organization: University of Maryland, College Park
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-
- In article <1992Jul22.085505.13897@vax5.cit.cornell.edu> blyy@vax5.cit.cornell.edu writes:
- >Big Question -
- >
- >I'm something of a novice at telecommunications, and I've recently purcahsed
- >a Supra FAXModem V.32bis. I'd like to maximize my transfer speed as much
- >as possible and would like any advice anyone has on the matter. So far, I've
- >been able to get approx. 100k per second using Jr-Comm 1.2, a 19200 connect
- >setting, and Ymodem-G protocal. Can anyone reccomend anything else I can
- >do to get the fastest throughput I can? Would connecting at 38400 help?
- >What about using XON/XOFF or CTS/RTS? Screen colors/depth? Protocol?
- >
- >P.S. THe Supra has a max baud rate of 14400. The manual, though, advises
- >connecting at 57600 to get the maximum connection. Is this okay?
-
- 100k per second? "You lucky, lucky, b......!" :-)
-
- 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
- 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.
-
-
- 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.
-
-
- 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"
-