lron@easy.HIAM (Dwight Hubbard) (10/07/90)
I noticed that new DSI modem advertised in computer shopper that could handle
V.32bis and V.42bis as well as V.29(who needs V.29). I was wondering if
anyone out there has used one of these babies and could tell me how many
characters per second on of these is capable of doing a Zmodem file transfer
of various file types (I'm asking this question for an owner of a USR HST 14.4
who wants to know if this new modem is faster than his HST)
--
-Dwight Hubbard, |-Kaneohe, HI
-USENET: uunet!easy!lron |-Genie: D.Hubbard1
lron@easy.hiam |-GT-Power: 029/004caf@omen.UUCP (Chuck Forsberg WA7KGX) (10/09/90)
In article <lron.1044734@easy.HIAM> lron@easy.HIAM (Dwight Hubbard) writes:
-I noticed that new DSI modem advertised in computer shopper that could handle
-V.32bis and V.42bis as well as V.29(who needs V.29). I was wondering if
-anyone out there has used one of these babies and could tell me how many
-characters per second on of these is capable of doing a Zmodem file transfer
-of various file types (I'm asking this question for an owner of a USR HST 14.4
-who wants to know if this new modem is faster than his HST)
V.42bis is a link level protocol, similar to MNP but in some ways better.
With V42bis, the answering modem interrogates the originating modem;
this avoids the problem with MNP interrogation confusing autobaud.
The compression in V.42bis does not slow transfers of pre compressed
files (ZIPfiles, etc.) as much as MNP5 does. As a result one can
generally turn on all ov V.42bis's features and not worry about it.
The newer HST modems use 14.4 kbps in the forward direction, which
gives higher potential ZMODEM speed than the 9.6 kbps raw throughput of
V.32 modems, and almost equal to the potential speed of V.32bis modems.
MNP and V.42 work well with ZMODEM; they have a net negative overhead
because they don't have to send start and stop bits, and their error
correcting strengths and weaknesses are complimentary to ZMODEM's.
There are differences in modems' ability to perform properly under
marginal line conditions and with various brands of modems, so your
mileage will vary. It will be a while bebore there are more V.32bis
modems on BBS systems than HSTs.
Chuck Forsberg WA7KGX ...!tektronix!reed!omen!caf
Author of YMODEM, ZMODEM, Professional-YAM, ZCOMM, and DSZ
Omen Technology Inc "The High Reliability Software"
17505-V NW Sauvie IS RD Portland OR 97231 503-621-3406
TeleGodzilla:621-3746 FAX:621-3735 CIS:70007,2304 Genie:CAF