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Conference hydra::amiga_v1

Title:AMIGA NOTES
Notice:Join us in the *NEW* conference - HYDRA::AMIGA_V2
Moderator:HYDRA::MOORE
Created:Sat Apr 26 1986
Last Modified:Wed Feb 05 1992
Last Successful Update:Fri Jun 06 1997
Number of topics:5378
Total number of notes:38326

1076.0. "Beating a dead horse (or Xmodem vs Kermit)" by VTHRAX::KIP (Entropy isn't what it used to be...) Thu Jan 14 1988 16:55

    Can anyone suggest which of Kermit or Xmodem would be better to
    use for downloading?  I've been using Kermit, it seems rather slow;
    have used XModem on Plink in the past, and believe that it would
    be faster due to larger packet size (I'm using VT100 R2.7 at present).
    I've tried using VMS XMODEM to download, but have not been able
    to get it to start.
    
    This has been mentioned before, but is anyone looking into WXmodem
    for VMS?  Last I've read it's available on Plink only.  Anyone have
    access to details of its operation (piggybacked acks?).  Seems like
    it would be handy to have...
T.RTitleUserPersonal
Name		DateLines
1076.1There's no clear answerNAC::PLOUFFLANsman WesThu Jan 14 1988 23:2921
    This has been discussed elsewhere in this conference, probably not
    under any obvious heading.  Briefly... Kermit _is_ slower because
    it uses 7-bit characters.  That means that some bytes need a prefix
    character to represent the eighth bit, adding maybe 1/3 to the length
    of a file.  XMODEM is faster if you can set up the entire data path
    to be eight bits.
    
    BUT, VMSland is more comfortable with 7-bit settings for historical
    reasons.  Kermit is better supported, people at Columbia U and a
    Digital Press book vs. word of mouth for XModem.  XModem is one
    of the few weak points of the VT100 emulator, as versions through
    R2.7 use checksum mode instead of the stronger CRC mode.  Both protocols
    have had extensions to longer packets, "sliding window" schemes
    to cut time wasted on acknowledging packets, better directory/file
    name handling, etc.  But none of this has shown up in VMS
    implementations inside the company.  None of the newest protocols,
    WX- Y- or Zmodem, has shown up in a VMS implementation.
    
    The best solution seems to be to use VT100 and Kermit when downloading
    from your local VAX, and a different terminal program with better
    flavors of XModem when downloading from a BBS or commercial service.