RFC 415 (rfc415) - Page 2 of 2

Tenex bandwidth

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RFC 415                     TENEX BANDWIDTH                November 1972


   THESE TESTS WERE RUN WITH NO OTHER LOAD ON OUR SYSTEM, AN EARLY
   VERSION OF 1.29.  THE INPUT AND OUTPUT HALVES OF THE TRANSMISSION
   HAVE BEEN AVERAGED TOGETHER.  I.E. THE ABOVE BAUD RATES WERE
   CALCULATED USING 2 MILLION BITS SINCE THE STRINGS WENT OUT AND IN.

OTHER PIECES OF DATA:

   OUR TTY'S AND LPT HAVE ULTIMATE CPU BANDWIDTHS NEAR 15-20 KB.  AT
   2400 BAUD, A TTY TAKES 15% OF THE CPU.  TELNETS NESTED THREE DEEP ARE
   ALMOST COMPUTE LIMITED WHEN JUST TYPING THINGS OUT ON A 2400 BAUD
   TERMINAL.

   AS A ROUGH CALCULATION, THE BANDWIDTH OF THE TIP TAPE TRANSMISSION
   FEATURE - USING STEVE BUTTERFIELD'S (OF BBN) NETMAG PROGRAM - IS
   ABOUT 7 KILOBITS/SEC.  ONE TAPE OF ABOUT 6,000 TENEX PAGES TOOK ABOUT
   4 HOURS TO TRANSMIT.  THIS WAS A FULL TAPE FROM ETAC TO CCA LATE ONE
   NIGHT WITH NOTHING ELSE RUNNING ON OUR SYSTEM.  ABOUT 30% OF THE CPU
   IS NEEDED TO MAINTAIN THIS BANDWIDTH.  AGAIN THIS IS ONLY ABOUT 20KB
   PER CPU SEC.


        [This RFC was put into machine readable form for entry]
    [into the online RFC archives by Helene Morin, Via Genie 12/99]




























Murray
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