Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!deimos!eecea!gordon
From: gordon@eecea.eece.ksu.edu (Dwight Gordon)
Newsgroups: comp.sys.ibm.pc
Subject: Re: XMODEM,YMODEM,ZMODEM,KERMIT Which is best and why?
Keywords: ZMODEM, KERMIT
Message-ID: <919@eecea.eece.ksu.edu>
Date: 1 Jan 90 14:58:25 GMT
References: <32428@news.Think.COM>
Reply-To: gordon@eecea.UUCP (Dwight W. Gordon)
Organization: Kansas State University, Manhattan, KS
Lines: 42

In article <32428@news.Think.COM> saroff@.tmc.edu (steven saroff) writes:
>I am interested in learning about the various flavors of transfer
>programs for PC's etc.

  My program of choice depends on the environment.

ZMODEM -
1.  Fast!  It gives me in excess of 10% greater throughput than KERMIT.
    (~230 cps on my 2400 baud modem)
2.  Requires 8-bit datalinks (at least my version does).
3.  Not as robust as KERMIT.
    a.  noisy environments (bad phone connections) causes troubles
    b.  multitasking (DesqView) a graphics (high cpu overhead) application
        in another window tends to cause retries/packet failures (yes, I
        know that there must be a way to tune the DesqView parameters so
        that this doesn't happen.  I haven't found it!)
4.  The ability to resume an aborted transfer is GREAT!
5.  "Problem connections" (see 3) cause ZMODEM to decrease the packet size.
    This will (hopefully) increase reliability.  However, it plays havoc
    with the throughput!  (I've seen it drop to <100 cps on 2400 baud.)

KERMIT
1.  Not as fast as ZMODEM (with 1K packets it claims about 208 cps on
    my 2400 baud modem)
2.  Works on both 7 and 8 bit connections.
    This sometimes causes problems with configuring KERMIT.  Some of the
    UNIX systems I've used will happily configure KERMIT for 8-bit, where
    the tty is set for 7-bit.
    (Our campus mainframe, KSUVM, only works with 7-bit datalinks!)
3.  ROBUST!  It was designed to transfer information between dissimilar
    machines.  I have seen it "give up" (see 3.b above).  It does so
    less often than ZMODEM.
4.  No direct support for aborted downloading.
5.  Packet size is negotiated at the start of the transfer, and doesn't
    change.

- Dwight -
-- 
Dwight W. Gordon, Ph.D.  |   913-532-5600    |   gordon@eecea.eece.ksu.edu
Electrical & Computer Engineering Department |     dwgordon@ksuvm.bitnet
Kansas State University - Durland Hall       | rutgers!ksuvax1!eecea!gordon
Manhattan, KS 66506      | {pyramid,ucsd}!ncr-sd!ncrwic!ksuvax1!eecea!gordon