rick@kimbal.lynn.ma.us (Rick Kimball) (11/23/89)
Summary: I decide to spend the extra money on the T2500 because there
are a bunch of US Robotic Dual Standard BBS around here. I
want to be able to connect to them. In addition, I get the
gut feeling that upgrades for the T2500 will be more
available than for the TB+.
Thanks to the following people for responding:
casey%gauss.llnl.gov@lll-crg.llnl.gov (Casey Leedom)
faatcrl!jimb@gvlv2.gvl.unisys.com (Jim Burwell)
"Mark Solsman" <MHS108@PSUVM.PSU.EDU>
Mark A. Verber <verber@pacific.mps.ohio-state.edu>
cca.ucsf.edu!wet!tempest@cgl.ucsf.edu
Rick Kimball INTERNET: rick@kimbal.lynn.ma.us
UUCP: ...!spdcc!kimbal!rick, ...!spt!kimbal!rick
Personal USENET Site POTS: (617) 599-8864
| I'm trying to decide between a TB+ and a T2500. Is it worth it to spend
| the extra money on the T2500. All the sites I communicate with at
| present use TB+. The traffic is mainly UUCP with occasional terminal
| connections.
Thats what TB+s (and T2500s) are best at. PEP/UUCP g spoofing is a great
combo.
First, it should be noted that the price difference between a TB+ and
a T2500 is really getting small (I'm speaking of actual prices you
would pay after shopping around - not list prices).
If your traffic is all UUCP, then you really don't need a V.32
modem. PEP will give you much better performance with UUCP
spoofing. The packetizing delay on a V.32 with MNP will really hurt
your UUCP performance.
If you do [visually] interactive work as well, I think you should
seriously consider the extra cost of getting a T2500. V.32 doesn't
have the funky echo delay of PEP. Most of the time the PEP echo
delay won't bother you if you're just typing something in, but if
you're doing anything that requires hand eye coordination, it's a
real mess.
I would go for the extra to get a t2500, I did. V.32 will be much
more standard than PEP. I expect that v.32 modems will be about
as common as v.22 (2400 baud) in five years. A number of the
commercial services are looking into installing v.32 modems.
V.32 is also nice because it is full duplex 9600 baud. Things
like SLIP are very usable on V.32 modems, and teribble under
PEP right now.
| What are the advantages and disadvantges to V.32?
V.32 is slower than PEP. It NEEDS (at least on our phone system)
MNP turned on to get a noisless connection (doesn't suprise me at
all. PEP must do EC also). The advantage is that it's now a
"common denominator" for the major high speed modems (USR HST DS,
Microcom V.32, Hayes V.32, Telebit, etc).
V.32 is a full duplex protocol at 9600bps. You wouldn't get
propagation delays like you would get from a PEP or HST modem.
It's only 9600bps, so throughput wouldn't be as good as PEP.
Interactive use would be superior, however.
PEP is a much more elegant protocol than HSTs. It breaks up the
phone line into 511 "channels" or band, on different frequencies, and
uses AM to squeeze as many bits down each channel (in paralell) per
baud as possible (up to 9 bpb! ).
You can get about 1800 CPS on a good line. HSTs DO do better on a
nice clean phone line, but PEP kills HST when there is line noise.
(PEP is the most robust modem-modem protocol I've seen. Nothing
short of disconnecting stops it from transfering! ). .
| Will [V.32] be superseded by something else.
It already is. V.42 is out. USR HST DS users will have chip upgrades RSN.
Telebit T2500 users will also get V.42 chips with the next ROM releases.
Along these lines I really like Telebit because they've proven that
they're committed to leading in this field and willing to offer
customers upgrade paths - usually at fairly reasonable cost.
| Can a T2500 using V.32 talk to a US Robotics or Hayes?
Only if the USR in question is a Dual Standard or V.32. Not sure
about Hayes, but I'm pretty certain it won't work on a V-Series.
Hayes did something weird and it's not fully V.32 compliant.
Right now, I think Telebit makes the best modems for Unix users.
T2500s are really nice. I must say that I haven't played with HST
Dual Standards yet. The older HSTs didn't have UUCP 'g' spoofing,
which practically makes it impossible to use with UUCP. Newer ones
now have spoofing.tempest@wet.UUCP (Ken Lui) (11/25/89)
In article <1074@kimbal.lynn.ma.us> rick@kimbal.lynn.ma.us (Rick Kimball) writes: >Thanks to the following people for responding: > ... > cca.ucsf.edu!wet!tempest@cgl.ucsf.edu > Glad to help. >| Will [V.32] be superseded by something else. > >It already is. V.42 is out. USR HST DS users will have chip upgrades RSN. > I thought V.42 and V.42bis only deals with error correction and data compression, respectively. >Telebit T2500 users will also get V.42 chips with the next ROM releases. > Would somebody working at Telebit want to comment on the possibility of receiving ROM upgrades that support V.42 and V.42bis? I would be really interested in an upgrade. A natural question would be will T2500s be V.42/V.42bis compatible or compliant. I read in an older issue of Data Communications that the two are not equivalent. Are the USRs compatible or compliant? Am I making any sense? >Along these lines I really like Telebit because they've proven that >they're committed to leading in this field and willing to offer >customers upgrade paths - usually at fairly reasonable cost. > I agree here. Ken -- _____________________________________________________________________________ Kenneth K.F. Lui | UUCP: ...{ucsfcca|claris}!wet!tempest tempest@wet.UUCP | Internet: cca.ucsf.edu!wet!tempest@cgl.ucsf.edu | -or- claris!wet!tempest@ames.arc.nasa.gov
chasm@attctc.Dallas.TX.US (Charles Marslett) (11/25/89)
In article <1074@kimbal.lynn.ma.us>, rick@kimbal.lynn.ma.us (Rick Kimball) writes: [Summary omitted.] > Thanks to the following people for responding: > casey%gauss.llnl.gov@lll-crg.llnl.gov (Casey Leedom) > faatcrl!jimb@gvlv2.gvl.unisys.com (Jim Burwell) > "Mark Solsman" <MHS108@PSUVM.PSU.EDU> > Mark A. Verber <verber@pacific.mps.ohio-state.edu> > cca.ucsf.edu!wet!tempest@cgl.ucsf.edu > > Rick Kimball INTERNET: rick@kimbal.lynn.ma.us > UUCP: ...!spdcc!kimbal!rick, ...!spt!kimbal!rick > Personal USENET Site POTS: (617) 599-8864 [Most of article omitted.] > | Will [V.32] be superseded by something else. > > It already is. V.42 is out. USR HST DS users will have chip upgrades RSN. > Telebit T2500 users will also get V.42 chips with the next ROM releases. Isn't V.42 just another data compression/error correction standard? Not really superceding V.32, but just replacing (or coordinating with) MNP4 and 5? I thought it was a standard for end-to-end error correction protocols. Wrong? That is, doesn't it really replace MNP4 (or whatever) with a slightly more comprehensive scheme which includes the MNP protocol? Charles Marslett <non-expert> at chasm@attctc.dallas.tx.us
jimb@faatcrl.UUCP (Jim Burwell) (11/26/89)
chasm@attctc.Dallas.TX.US (Charles Marslett) writes: >In article <1074@kimbal.lynn.ma.us>, rick@kimbal.lynn.ma.us (Rick Kimball) writes: >[Summary omitted.] >> Thanks to the following people for responding: >> casey%gauss.llnl.gov@lll-crg.llnl.gov (Casey Leedom) >> faatcrl!jimb@gvlv2.gvl.unisys.com (Jim Burwell) >> "Mark Solsman" <MHS108@PSUVM.PSU.EDU> >> Mark A. Verber <verber@pacific.mps.ohio-state.edu> >> cca.ucsf.edu!wet!tempest@cgl.ucsf.edu >> >> Rick Kimball INTERNET: rick@kimbal.lynn.ma.us >> UUCP: ...!spdcc!kimbal!rick, ...!spt!kimbal!rick >> Personal USENET Site POTS: (617) 599-8864 >[Most of article omitted.] Rick said: >> | Will [V.32] be superseded by something else. >> Then I said: >> It already is. V.42 is out. USR HST DS users will have chip upgrades RSN. >> Telebit T2500 users will also get V.42 chips with the next ROM releases. Then you asked: >Isn't V.42 just another data compression/error correction standard? Not really >superceding V.32, but just replacing (or coordinating with) MNP4 and 5? I >thought it was a standard for end-to-end error correction protocols. Wrong? >That is, doesn't it really replace MNP4 (or whatever) with a slightly more >comprehensive scheme which includes the MNP protocol? I don't have any technical specs in front of me, but someone told me that V.42 was a new modem to modem protocol, which combined "lapb/lapm, trellis encoding" etc etc. (Byte wrote a good article on all this stuff a while back). As far as I know, MNP just sits on top of a underlying low-level protocol, or modem engine. Adding a higher MNP level (I think it goes up to 9) wouldn't change the CCITT spec, I would think. Someone else told me that V.42 was simply the protocol which Hayes uses in it's V-series modems. Anyway, as far as I know, it will be better than V.32, and HSTs and T2500s, and many other modems will support it... BTW: for the person who asked, Telebit IS coming out with V.42 roms RSN. I read it in a letter which Telebit sent with its latest upgrade roms.. Bye Jim