met@sactoh0.SAC.CA.US (Marc E. Tarpenning) (10/02/90)
I am thinking of buying a Telebit T2500 modem and am a little concerned about the number of posted problems with this modem. Should I buy one? Also, I noticed that it does not support V.42 or V.42bis. What exactly is this format used for? -- "We will not fail." - Don Pedro, Henry V. Internet: met@sactoh0.SAC.CA.US Cis: 71435,1753 SnailMail: P.O. 254801, Sacramento, CA 95865, USA Fax: 916-481-6467
mju@mudos.ann-arbor.mi.us (Marc Unangst) (10/03/90)
met@sactoh0.SAC.CA.US (Marc E. Tarpenning) writes: > Also, I noticed that it does not support V.42 or V.42bis. What exactly is > this format used for? Where'd you hear this? My T2500 came with an insert to the docs entitled "Telebit T2500 Modem Release 7.00 Addendum", which talks all about V.42 and V.42bis. V.42, FYI, is the CCITT's error-correction protocol for 2400 and 1200 bps modems. V.42bis is a compression protocol that can increase speed up to four times over a V.42 link. -- Marc Unangst | "Decryption is not supported by crypt(C) in the mju@mudos.ann-arbor.mi.us | export version of SCO Unix." ...!umich!leebai!mudos!mju | -- SCO User Guide, Open DeskTop
grr@cbmvax.commodore.com (George Robbins) (10/03/90)
In article <sR1Fq1w163w@mudos.ann-arbor.mi.us> mju@mudos.ann-arbor.mi.us (Marc Unangst) writes: > met@sactoh0.SAC.CA.US (Marc E. Tarpenning) writes: > > Also, I noticed that it does not support V.42 or V.42bis. What exactly is > > this format used for? > > Where'd you hear this? My T2500 came with an insert to the docs > entitled "Telebit T2500 Modem Release 7.00 Addendum", which talks all > about V.42 and V.42bis. V.42, FYI, is the CCITT's error-correction > protocol for 2400 and 1200 bps modems. V.42bis is a compression > protocol that can increase speed up to four times over a V.42 link. Well, the vast majority of them don't support V.42, so I guess maybe it's time to send for some new roms... 8-) BTW, looking at your addendum, did they add support for a 38.4 KBPS interface rate? If not, then it's going to be real hard to get a 4X performance boost at 9600 BPS, eh? -- George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr but no way officially representing: domain: grr@cbmvax.commodore.com Commodore, Engineering Department phone: 215-431-9349 (only by moonlite)
j_prigot@wrglex.uucp (10/04/90)
In article <4100@sactoh0.SAC.CA.US>, met@sactoh0.SAC.CA.US (Marc E. Tarpenning) writes: > I am thinking of buying a Telebit T2500 modem and am a little concerned > about the number of posted problems with this modem. Should I buy one? I think that most of the problems stem from the number of ways they can be configured. (There is a problem with some register settings and callback security in Release 6, but that is a minor nit.) We use them for just about every form of communication (async for terminals/PCs, sync for CPUs/MUXs) and are quite satisfied. They have been upgraded once within the warranty period for free, and tech support is as good as is advertised. > > Also, I noticed that it does not support V.42 or V.42bis. What exactly is > this format used for? > It does with the Release 6 firmware. V.42 is the LAP-M alternative to MNP/4. V.42bis is a compression algorithm based on V.42. -- Jonathan M. Prigot j_prigot@wrglex or ...!drilex!wrglex!j_prigot
mju@mudos.ann-arbor.mi.us (Marc Unangst) (10/04/90)
grr@cbmvax.commodore.com (George Robbins) writes: > BTW, looking at your addendum, did they add support for a 38.4 KBPS interface > rate? If not, then it's going to be real hard to get a 4X performance boost > at 9600 BPS, eh? I think V.42 and V.42bis are only useful at 1200bps and 2400bps (V.22, Bell 212A, and V.22bis), although they may also work at 9600bps (V.32). The addendum doesn't say anything about talking to the modem at 38.4Kbps, and since the manual doesn't say either, I'd guess that 19.2Kbps is still as high as you can go. -- Marc Unangst | "Decryption is not supported by crypt(C) in the mju@mudos.ann-arbor.mi.us | export version of SCO Unix." ...!umich!leebai!mudos!mju | -- SCO User Guide, Open DeskTop
brian@fog.ann-arbor.mi.us (Brian S. Schang) (10/04/90)
>> Where'd you hear this? My T2500 came with an insert to the docs >> entitled "Telebit T2500 Modem Release 7.00 Addendum", which talks all >> about V.42 and V.42bis. V.42, FYI, is the CCITT's error-correction >> protocol for 2400 and 1200 bps modems. V.42bis is a compression >> protocol that can increase speed up to four times over a V.42 link. What is different between the Telebit T2500 7.00 Release and the previous 6.?? versions? Anything significant? Thanks... -- Brian S. Schang N8FOG brian@fog.ann-arbor.mi.us 46131 Academy Drive schang@caen.engin.umich.edu Plymouth, MI 48170-3519
casey@gauss.llnl.gov (Casey Leedom) (10/04/90)
/ From: grr@cbmvax.commodore.com (George Robbins) | | BTW, looking at your addendum, did they add support for a 38.4 KBPS interface | rate? If not, then it's going to be real hard to get a 4X performance boost \ at 9600 BPS, eh? / From: mju@mudos.ann-arbor.mi.us (Marc Unangst) | | I think V.42 and V.42bis are only useful at 1200bps and 2400bps (V.22, | Bell 212A, and V.22bis), although they may also work at 9600bps | (V.32). The addendum doesn't say anything about talking to the modem | at 38.4Kbps, and since the manual doesn't say either, I'd guess that \ 19.2Kbps is still as high as you can go. It works quite nicely in V.32/V.42bis mode. I use it all the time. However, I'm now getting nearly 19,200 full blast. There are times when I definitely think I'm limited by the 19.2Kbps top interface rate on the T2500. I don't think it's a big problem yet because the 4x throughput rate for V.42bis is a maximum and I would bet that it's averaging about 2x. But, when V.32bis is brought out with a base rate of 14.4Kbps, a V.42bis maximum rate of 57.6Kbps and an expected average of maybe 28.8Kbps, 19.2Kbps is going to be totally inadequate. I brought this issue up with an engineer from Telebit. I asked him if they were thinking about adding a 38.4Kbps interface speed setting to the T2500. He said yes, they were thinking about it but didn't know if the T2500 had the CPU horse power to handle that kind of rate. He pointed out that the T2500 was really just their old platform with a V.32 engine tacked on top. Oh well. Nothing is forever. I presume that Telebit will offer T2500 owners an upgrade path if new hardware is required. They've been very good about that in the past. It is somewhat disappointing because when Telebit brought out the T2500 they claimed that the old design wasn't fast enough to handle V.32 and thus the T2500 design would incorporate enough CPU to handle the current and near future needs. Or maybe I was just reading between the lines. Casey
mju@mudos.ann-arbor.mi.us (Marc Unangst) (10/04/90)
casey@gauss.llnl.gov (Casey Leedom) writes: > I brought this issue up with an engineer from Telebit. I asked him if they > were thinking about adding a 38.4Kbps interface speed setting to the T2500. I brought this up with the tech support guy tonight when we were working on speeding up my UUCP throughput. He said that they had NO plans to add 38.4Kbps to the T2500 in the near future. He also said that if it was ever done, it would be more involved an upgrade than just a ROM change -- most likely a logic board swap. In other words, "not on this hardware platform." -- Marc Unangst | "Decryption is not supported by crypt(C) in the mju@mudos.ann-arbor.mi.us | export version of SCO Unix." ...!umich!leebai!mudos!mju | -- SCO User Guide, Open DeskTop
ccplumb@spurge.uwaterloo.ca (Colin Plumb) (10/04/90)
In article <4100@sactoh0.SAC.CA.US> met@sactoh0.SAC.CA.US (Marc E. Tarpenning) writes: > I am thinking of buying a Telebit T2500 modem and am a little concerned > about the number of posted problems with this modem. Should I buy one? I think the frequency of problem reports is more a reflection of the number of people using them than the number of problems per person. It *does* take a while to learn your way around the zillions of parameters you can diddle, though. -- -Colin
cyamamot@kilroy.Jpl.Nasa.Gov (Cliff Yamamoto) (10/04/90)
In article <69198@lll-winken.LLNL.GOV> casey@gauss.llnl.gov (Casey Leedom) writes: > It works quite nicely in V.32/V.42bis mode. I use it all the time. >However, I'm now getting nearly 19,200 full blast. There are times when I >definitely think I'm limited by the 19.2Kbps top interface rate on the T2500. >I don't think it's a big problem yet because the 4x throughput rate for >V.42bis is a maximum and I would bet that it's averaging about 2x. But, when >V.32bis is brought out with a base rate of 14.4Kbps, a V.42bis maximum rate of ^^^^^^^^^^^^^^^^^^^^^^ >57.6Kbps and an expected average of maybe 28.8Kbps, 19.2Kbps is going to be >totally inadequate. Does anyone know when V.32bis will come out? Are there any modems out there that will be upgradable to V.32bis with a simple ROM or board change? Is V.32bis similar to 14.4K HST Link mode? -- Cliff
jeff@xanadu.com (Jeff Crilly N6ZFX) (10/05/90)
In article <1990Oct4.032952.21956@watdragon.waterloo.edu> ccplumb@spurge.uwaterloo.ca (Colin Plumb) writes: >In article <4100@sactoh0.SAC.CA.US> met@sactoh0.SAC.CA.US (Marc E. Tarpenning) writes: >> I am thinking of buying a Telebit T2500 modem and am a little concerned >> about the number of posted problems with this modem. Should I buy one? > >I think the frequency of problem reports is more a reflection of the number >of people using them than the number of problems per person. It *does* >take a while to learn your way around the zillions of parameters you >can diddle, though. >-- > -Colin Marc -- Colin is correct. However, other high speed modems like the USRobotics HST-Dual, also have zillions of registers with semi-confusing purpose. We have a collection on T2500s and they all work fine. We also have a collection of HST-Duals and they work fine too. You need to figure out what you need. If you just want V.32 then any modem will do, and you must decide on other factors like service. If you have uucp connections then I suggest you get a T2500 and make use of PEP and uucp spoofing. If you call BBSs all the time then maybe you should consider a HST-Dual (although, in the little BBSing that I have done, I haven't seen much of these -- mostly 2400 bps stuff). Also, keep in mind that the major online services like compuserve and genie will be supporting V.32. Jeff Crilly (N6ZFX) AMIX Corporation 2345 Yale Street Palo Alto, CA 94306 jeff@amix.com, {uunet,sun}!markets!jeff, N6ZFX@N6IIU.#NOCAL.CA.USA
tnixon@hayes.uucp (Toby Nixon) (10/07/90)
>> BTW, looking at your addendum, did they add support for a 38.4 KBPS interface >> rate? If not, then it's going to be real hard to get a 4X performance boost >> at 9600 BPS, eh? > > I think V.42 and V.42bis are only useful at 1200bps and 2400bps (V.22, > Bell 212A, and V.22bis), although they may also work at 9600bps > (V.32). > > Marc Unangst Do you mean that you think V.42 and V.42bis are only useful in the T2500 are 1200 and 2400? I don't know from personal experience, but I'm sure they also support these with V.32 modulation. Certainly, V.42 and V.42bis are standardized by the CCITT for use on V.32, and will also work with the upcoming V.32bis standard (14,400bps modulation, 57,600 throughput with V.42bis). -- Toby ----------------------------------------------------------------------------- Toby Nixon, Principal Engineer Fax: +1-404-441-1213 AT&T: !tnixon Hayes Microcomputer Products Inc. Voice: +1-404-449-8791 CIS: 70271,404 Norcross, Georgia, USA BBS: +1-404-446-6336 MCI: TNIXON UUCP: ...!uunet!hayes!tnixon Internet: hayes!tnixon@uunet.uu.net
tnixon@hayes.uucp (Toby Nixon) (10/07/90)
In article <1990Oct4.144517.17005@elroy.jpl.nasa.gov>, cyamamot@kilroy.Jpl.Nasa.Gov (Cliff Yamamoto) writes: > Does anyone know when V.32bis will come out? Are there any modems out there > that will be upgradable to V.32bis with a simple ROM or board change? Is > V.32bis similar to 14.4K HST Link mode? V.32bis is scheduled to be voted on for accelerated approval at the 15-23 October 1990 meeting of CCITT Study Group XVII in Geneva. Barring unforeseen objections, it should pass. It is then sent out for a written ballot to all CCITT member countries. The ballot period will end around the end of February, 1991. Assuming the ballot at the meeting is unanimous, and the written ballot is 70% in the affirmative, V.32bis will be an official CCITT standard as of then (Feb '91). Only a couple of companies have announced V.32bis capability so far: Forval, Digicom, and Penril (that I'm aware of). These aren't as far as I know, V.32 modems that are upgradable to V.32bis, but are designed to be V.32bis from the start. The companies are taking a big risk by shipping products before the standard has even undergone it's first vote, especially since some of the negotiation parameters were changed just this summer. If you even think about buying one in advance of the finalization of the standard, be sure to get a commitment to upgrade to full compliance. V.32bis is similar in only one respect to the HST modulation scheme: the signal constellation at 7,200, 12,000, and 14,400. They're not at all compatible, however. The HST is asymmetrical (high speed one direction, low speed [300/450bps] reverse channel in the other), while V.32bis is full-duplex symmetrical with echo cancellation. Because V.32bis mandates backward compatible with V.32, you can talk at 9600 between a USR HST Dual Standard and a V.32bis modem, but not with an HST-only modem. -- Toby ----------------------------------------------------------------------------- Toby Nixon, Principal Engineer Fax: +1-404-441-1213 AT&T: !tnixon Hayes Microcomputer Products Inc. Voice: +1-404-449-8791 CIS: 70271,404 Norcross, Georgia, USA BBS: +1-404-446-6336 MCI: TNIXON UUCP: ...!uunet!hayes!tnixon Internet: hayes!tnixon@uunet.uu.net
mju@mudos.ann-arbor.mi.us (Marc Unangst) (10/07/90)
tnixon@hayes.uucp (Toby Nixon) writes: > Do you mean that you think V.42 and V.42bis are only useful in the > T2500 are 1200 and 2400? I don't know from personal experience, but > I'm sure they also support these with V.32 modulation. Yes, this was what I meant; sorry for any confusion. The T2500 is capable of making a 9600bps V.32 connection, with V.42 and V.42bis active. The part about not working at 9600 was a slip on my part; I was thinking of PEP mode, where any sort of compression and/or error-correction would be useless because PEP provides it internally. -- Marc Unangst | "Decryption is not supported by crypt(C) in the mju@mudos.ann-arbor.mi.us | export version of SCO Unix." ...!umich!leebai!mudos!mju | -- SCO User Guide, Open DeskTop
wb8foz@mthvax.cs.miami.edu (David Lesher) (10/07/90)
{discussion on 2500 port speeds, V.42, compression, and the
meaning of life ;-] deleted}
None of which says that a 2500 would not benefit from higher
port speeds. Then, of course, you run into the problem of the
receiving box not being able to swallow stuff quickly enough.
I seem to recall someone suggesting an etherhose faucet on the
back of a Blazer. ISTM that Bill Mayhew did just that, so to
speak, by devoting a 3B1 to the Blazer, and hosing it elsewhere.
I guess I'm dating myself, but I remember agonizing over ALL
that money for a direct connect 1200 bps modem. How could ANYONE
ever need all that speed ;_?
--
A host is a host from coast to coast.....wb8foz@mthvax.cs.miami.edu
& no one will talk to a host that's close............(305) 255-RTFM
Unless the host (that isn't close)......................pob 570-335
is busy, hung or dead....................................33257-0335bob@MorningStar.Com (Bob Sutterfield) (10/11/90)
In article <1990Oct4.032952.21956@watdragon.waterloo.edu> ccplumb@spurge.uwaterloo.ca (Colin Plumb) writes:
It *does* take a while to learn your way around the zillions of
parameters you can diddle, though.
Don't think of them as registers and parameters, think of them as
syntax elements of a programming language. I suspect that the TB is
the first Turing-complete modem :-)