c60b-1eq@e260-1g.berkeley.edu (Noam Mendelson) (04/28/91)
In article <1991Apr27.154039.6656@wlbr.imsd.contel.com> mcc@WLV.IMSD.CONTEL.COM (Merton Campbell Crockett) writes: >In article <1991Apr27.053539.10761@agate.berkeley.edu> c60b-1eq@e260-1e.berkeley.edu (Noam Mendelson) writes: >>In article <1991Apr27.031643.23049@wlbr.imsd.contel.com> mcc@WLV.IMSD.CONTEL.COM (Merton Campbell Crockett) writes: >>> 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 2510-2560 bps figure for text data is due to Kermit's RLE compression, >Sorry about that. I should have indicated that setting the windows to 1--ie >disabling the sliding windows option--yields an effective transfer rate in >the 2280-2340 bps range for text data. Yes, that would sound reasonable. Note that even with sliding windows, a larger packet may yield greater transfer rates since there is some overhead involved when a new packet is sent. Although sliding windows minimizes this delay (since it doesn't have to wait for the ACK, which is the most time-consuming aspect of new packets), it still exists. However, if you're expecting any errors at all, a smaller packet size will yield higher transfer rates. >Probably should have also noted that MS-Kermit 3.10 now provides an automatic >detection and notification of a 7 bit data link in the path between the local >and remote system. When a 7 bit data link is detected and the file type >is set to binary, the binary data is encoded to traverse the 7 bit data link >segment. A useful feature when you forget the -8 switch to rlogin. The 8th bit prefix is an old feature of the Kermit protocol. Although ZMODEM should theoretically be capable of handling 7-bit lines, all implementations that I've seen don't. Kermit is the only one which groks the 7-bit lines. -- +==========================================================================+ | Noam Mendelson ..!ucbvax!web!c60b-1eq | "I haven't lost my mind, | | c60b-1eq@web.Berkeley.EDU | it's backed up on tape | | University of California at Berkeley | somewhere." |