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From: caf@omen.UUCP
Newsgroups: comp.sys.ibm.pc,comp.dcom.modems,comp.unix.wizards,comp.unix.xenix
Subject: XMODEM, YMODEM, ZMODEM w/32 bit CRC Unix Progs Posted
Message-ID: <458@omen.UUCP>
Date: Fri, 16-Jan-87 05:12:35 EST
Article-I.D.: omen.458
Posted: Fri Jan 16 05:12:35 1987
Date-Received: Sat, 17-Jan-87 15:53:31 EST
Organization: Omen Technology, Portland
Lines: 20
Xref: watmath comp.sys.ibm.pc:960 comp.dcom.modems:141 comp.unix.wizards:605 comp.unix.xenix:53

New versions of the Unix/Xenix XMODEM, YNODEM, and ZMODEM programs
rz and sz have been posted to net.sources in two parts.

The reliability of ZMODEM file transfers has been enhanced with the
addition of a table driven 32 bit CRC.  ZMODEM downloads from Unix to
PC's are much more efficient than XMODEM or Kermit.  For example, 9600
baud downloads from a 9 mHz PC-AT Xenix machine to Crosstalk XVI gave
343 characters per second throughput, Kermit gave 327 characters per
second, and ZMODEM gives 915 characters per second.  At 19200 baud,
ZMODEM downloads to a 4.77 mHz PC hard disk attain 1870 characters per
second throughput.  Note that the 343 cps throughput with Crosstalk was
with an 8 bit checksum while ZMODEM uses 32 bit CRC for >7 orders of
magnitude better data reliability. 

Chuck Forsberg WA7KGX Author of Pro-YAM communications Tools for PCDOS and Unix
...!tektronix!reed!omen!caf  Omen Technology Inc "The High Reliability Software"
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