Xref: utzoo comp.sys.laptops:2654 comp.sys.ibm.pc.misc:9093 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!europa.asd.contel.com!wlbr!WLV.IMSD.CONTEL.COM!mcc From: mcc@WLV.IMSD.CONTEL.COM (Merton Campbell Crockett) Newsgroups: comp.sys.laptops,comp.sys.ibm.pc.misc Subject: Re: Comm programs, Crosstalk Mk IV Message-ID: <1991Apr27.031643.23049@wlbr.imsd.contel.com> Date: 27 Apr 91 03:16:43 GMT References: <1991Apr21.071509.13167@news.iastate.edu> <1991Apr21.085326.28167@agate.berkeley.edu> Sender: news@wlbr.imsd.contel.com (news) Organization: Contel Federal Systems Lines: 31 Nntp-Posting-Host: wlv.imsd.contel.com In article <1991Apr21.085326.28167@agate.berkeley.edu> c60b-1eq@e260-1a.berkeley.edu (Noam Mendelson) writes: >In article <1991Apr21.071509.13167@news.iastate.edu> vancleef@iastate.edu (Van Cleef Henry H) writes: >> ... The only thing >>against Kermit is that while the transfer is pretty >>reliable, the frog doesn't jump awfully high---X/Y/Zmodem >>are faster for most purposes. >Not necessarily. On clean lines, if you set the blocksize to 1K and >the check to a 3-byte CRC, you'll get decent throughput (that of YModem). >And, as a block protocol (as opposed to the streaming ZMODEM), it tends >to be a lot more reliable under non-standard conditions. >It's too bad that MS-Kermit doesn't support sliding windows yet. *sigh* The comment concerning sliding window support is erroneous. MS-Kermit 3.10 does support sliding windows. In most cases, the problem is that the remote end does not support sliding windows. In file transfers through a 2400 baud modem link using 512 byte packets and 3 windows, an effective baud rate of 2510 to 2560 is typical transfer rate for text files. The effective baud rate decreases as you decrease the packet size; however, I haven't noticed any improvement in the effective baud rate as you increase the packet size from 512 bytes. The above data was obtained from a path that also involved a 7 bit rlogin link over an ethernet. Using "direct" connections over a broadband at 9600 and 19.2K the effective baud rate is around 9000 and 18K, respectively. The broadband has some problems with flow control and lost data at 19.2K. This environment demonstrates a "secondary" feature of the MS-Kermit windows op- tion--automatic down-sizing of the packet on detection of errors and restor- ation of the original packet size when error conditions have cleared. Merton Campbell Crockett