Path: utzoo!attcan!uunet!husc6!mailrus!ames!pasteur!ucbvax!SIMTEL20.ARPA!W8SDZ From: W8SDZ@SIMTEL20.ARPA (Keith Petersen) Newsgroups: comp.dcom.modems Subject: 9600 bps modem observations - USR HST and TrailBlazer Message-ID: Date: 12 Jun 88 16:53:00 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 41 I downloaded about 20 files from a local BBS which has a USR HST 9600 modem, using DSZ (the MSDOS zmodem program) on both ends. The throughput is quite impressive, running between 940 and 1040 cps. No compression was done in the modems because the files were already compressed using the MSDOS ARC program. This is very impressive performance and equals what I got when I borrowed the TrailBlazer for a few weeks (ROM ver. 4.0) and downloaded some files from Chuck Forsberg's (zmodem author) BBS using the same protocol. In all cases noted above both ends used an interface speed of 19200 in order to fill the modem communications buffer as quickly as possible. Dropping the interface speed to 9600 resulted in a reduction of throughput - dropping to 450-650 cps. It's very evident that these packetized modems *must* be driven at higher than their transmission speed in order to get the optimum throughput. I just got word yesterday that USR is coming out with an update for the HST to increase the reverse channel to 450 bps. That might not sound like much compared to 300, but should improve the interactive terminal session response considerably. While attending the Trenton Computer Festival I learned that almost 90% of the BBSs in the country that are using 9600 bps are using the USR HST. This is across-the-board for all types of microcomputer BBS systems, not just the IBMPC. While it is true that the TrailBlazer is becoming the defacto standard for Usenet hosts, I think the reason for this is the uucp-spoofing. In the real world of DDN host interactive terminal usage I feel that the HST would be a far better choice for dial-in ports which are not normally used for dialing out because the host is connected to the network for communication with other hosts. --Keith Petersen Maintainer of the CP/M and MSDOS archives at SIMTEL20.ARPA [26.0.0.74] Arpa: W8SDZ@SIMTEL20.ARPA Uucp: {decwrl,harvard,lll-crg,ucbvax,uunet,uw-beaver}!simtel20.arpa!w8sdz GEnie: W8SDZ RCP/M Royal Oak: 313-759-6569 - 300, 1200, 2400 (V.22bis) or 9600 (USR HST)