PR> 
MSGID:  0018efff
PR> JT> SB> With a 144 modem 13-1500 cps is about right.  To get
PR> JT> SB> faster
PR> JT> AT> Actually you should be looking more towards 1600cps..
PR> JT>You guys are gettin' my goat.:-(
PR> JT>I always average about 1365cps running 14.4 from a 33.6
PR> JT>and no matter what settings I play with, thats what I get.
PR> 
PR> IMO this thread seems to point out how little most of us understand
PR> about the virtually plug and play device called a modem.
PR> 
PR> As I understand it there are 8 bits to each character.  If one's thruput
PR> is running at about 1000 characters per second (cps), this equates to
PR> 8000 bits per second (bps).  1500 cps equates to 12,000 bps. Now,
PR> achieving only 12K bps or less from a device rated at 14.4K bps seems
PR> problematic to me.  I understand there are various factors that can
PR> impact thruput.  But when I posed my original message, I was hoping
PR> somone could help me understand either why my typical thruput of
PR> 1300-1500 cps from a 14.4 Kbps is correct OR whether any measures could
PR> be taken to make improvements.
PR> 
PR> Any takers?
PR> 
    There are 8 bits/character, but with a standard async modem connection
    you'll be adding stop and start bits as well to bring it up to 10 bits
    per character.  This really isn't a consideration though, since your
    error correction protocol will most likely be stripping the stop and
    start bits off before the data is sent.  Your throughput of 1300-1500
    cps is just a little slower than normal, but there are many factors that
    can affect throughput: phone line noise, system speed on either end
    (a heavily tasked cpu can slow things down), the type of UART in
    the serial cards, the file transfer protocol being used, the type of
    data being transferred (compressible or not), etc. etc.  If you
    are transferring fully compressed files under good conditions with a
    full streaming file transfer protocol like Zmodem and with a port
    speed set to at least 19,200 bit/s, 1600 cps is about average.
Michael -- Hayes Online Services
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