Carra_its-me_Bussa@cup.portal.com (08/16/90)
(Sorry if this is a rehash, but I can't exactly find any comparisons....)
I'm planning on getting a high-speed modem. There SEEM to be 3 types:
USR HST modems using MNP 5 (giving 19.2)
v.32 modems using v.42bis (Hayes V-series & others)
Telebit PEP modems
HST (5+) uses compression to increase their speed over the single carrier.
V.32 runs at 9600 FDX, w/v.42bis to double it's speed over the single carrier.
PEP uses multiple carriers (unlike Hayes/USR HST) and can slowly(?)
lower the baud and/or change working carriers as the line changes.
USR has the dual v32/HST modem; Hayes has the Ultra modem. Both of these
do MNP5 and v.32, and can talk to each other (right?)
The telebit modems use PEP, but the 1000 is PEP 9600, the + is 9600/v.32,
and the 2500 is PEP/v.32/HST (?) (MNP 5??)
So I can use the (external?) T2500 and talk to any modem known to man?
Just trying to get my facts straight before I plunk down a megagram of pennies
Thanks!
Carra Bussa @ cup.portal.com
(If this is a known subject, just email me. If lots of requests appear, I'll
summarize.)vernon@hpcvaac.cv.hp.com (Vernon King) (08/17/90)
We tested the telebit 2500 and it seems a good choice if you want to talk
uucp and v32. Price was around $1000. On the front of the unit was a switch
that allowed you to load one configuration in a and another in b. This would
allow you to funtion in both worlds easily.
Datacom-r-us
VernonCarra_its-me_Bussa@cup.portal.com (08/17/90)
OK gang, I'm dumb. I'm trying to decide which high-speed modem to buy.
I'm looking at 3 modems in particular:
brand "street prices" who
Hayes Ultra $900 (PC Connection (the raccoon people))
USR HST Dual $1000 (PC Brand)
Telebit T2500 $870 (AnDATAco)
A Hayes Ultra 9600 baud (Hayes blurb) has:
v.32 (real AND ping-pong), v.42/42bis, MNP 5, and x.25 (!)
A USR HST Dual has HST with MNP5, and v.32. (New and upgraded models also
have v.42/42bis) (There are models for JUST v.32 or HST, around $500,
but I don't care.)
A Telebit T2500 has PEP (DAMQAM), v.32, v.42 (but not v.42bis??) and MNP 5.
In a nutshell:
USR HST modems are run (mostly) by msdos BBSs. People are buying
dual (v.32/HST) modems so they won't become obsolete as HST is
slowly replaced with v.32. [like the speed of the "logical" XT
dying - the limitations linger on long after the physical box
has been junked.] Duals also seem to have a problem connecting
to other v.32 modems (somtimes - I've seen a lot of messages
griping about that lately.)
Hayes Ultras are v.32/v.42/v.42bis modems with x.25. They'll
talk to the earlier Hayes 9600 baud modems (v.32HDX) and can
handle MNP 5 as well. "Corporate" users like these because
A) they're fast, and B) the name. These act like normal v.32
modems but they have x.25 built in.
Telebits A (new) T2500 has PEP, v.32/v.42 and MNP5. (no v.42bis?) Unix
systems like Telebits (due to UUNET's discount?) and transmit data
at 19200 effective. I assume slow (not abrupt) degredation will
occur when line quality degrades.
?s: A Hayes Ultra should be able to call a T2500 or Dual using v.32.
How about using HST/Dual or PEP/Telebit with a Ultra?
Same question: I thought MNP 5 _WAS_ HST. It's NOT, is it??
v.32bis will be finished Feb 91 or later. Any guesses for modem
firmware upgrades? Completion, elapsed time, throughput, $, etc.
The lower Telebits (T1000 - T2499) don't do as much as the T2500.
What, why, and how much?
Telebits are supposed to have 9 different modulation schemes.
Pop quiz: what ARE they? (Hint: 1 is PEP)
Bonus question: Which one do I get???
(I'm leaning towards the T2500)
Any info would be appreciated, I can't be the ONLY one confused by all this.
By the way, there is a very interesting article in the July, 1990 issue
of Vulcan's Computer Monthly. (like Computer Shopper on a diet :-) )
There are general articles about modems, and on page 129 there is an
article by D.F. Scott. He manages to talk to USR, Telebit, GE Info,
Microcom (of MNP fame) and Hayes. He talks about how all the companies
got to where they are today with their own standards. Nice article!
Sometimes articles in CS, PC Mag, etc. are just plain WRONG. Nobody
actually bothered to check out the facts. This guy at least goes to the
source. If next month's issue is similar to this one, CS has lost a
reader.
FYI, USR and Hayes both have a "sysop" modem special --
USR/ Dual/ $700/800-DIAL-USR (voice)
Hayes/Ultra/$600/800-874-2937 (data)
UUNET has Telebit modems available to normal people, see info@uunet.uu.net.
(But AnDATAco is supposed to be a little cheaper.)
Carra Bussa @ cup.portal.com (Hi JFT!)
A black hole is just /dev/null come to life - me.tempest@wet.UUCP (Ken Lui) (08/17/90)
In article <32867@cup.portal.com> Carra_its-me_Bussa@cup.portal.com writes: >(Sorry if this is a rehash, but I can't exactly find any comparisons....) > >I'm planning on getting a high-speed modem. There SEEM to be 3 types: > >USR HST modems using MNP 5 (giving 19.2) >v.32 modems using v.42bis (Hayes V-series & others) >Telebit PEP modems > >HST (5+) uses compression to increase their speed over the single carrier. The HST sports the fastest transfer speed over normal telephone lines. Its 14.4kbps carrier used in conjunction with MNP 3 and above results in normal transfer rates of 16.0kbps-17.0kbps. These figures come from transferring pre-compressed files. >V.32 runs at 9600 FDX, w/v.42bis to double it's speed over the single carrier. V.32 with V.42bis will not double its transfer speed when sending/receiving pre-compressed files. It works great with TEXT files, but will be roughly give you the same performance when transferring pre-compressed files. >PEP uses multiple carriers (unlike Hayes/USR HST) and can slowly(?) > lower the baud and/or change working carriers as the line changes. > Yes, and that's the great thing about PEP. Connections are solid unlike V.32. My experiences in calling systems though _satellite links_ show that V.32 will almost always drop carrier during a session while a PEP connection rarely drops carrier. This was during the Alaskan volcano eruption when tons of ash spewed into the atmosphere blocking the satellite link for brief periods. Transfer throughput was down but I rarely lost a connection. V.32 connections are reliable within the 48 states, however. >USR has the dual v32/HST modem; Hayes has the Ultra modem. Both of these >do MNP5 and v.32, and can talk to each other (right?) > Yes. The two will also talk to a Telebit T2500 in V.32 mode and a T1500 (the T1500 is only V.32, no PEP). If you only want PEP, there's the T2000 that also supports SNA/HDLC connections. The Trailblazer Plus supports only PEP. The T2500 supports everything the T2000 supports and V.32. > >The telebit modems use PEP, but the 1000 is PEP 9600, the + is 9600/v.32, >and the 2500 is PEP/v.32/HST (?) (MNP 5??) > The T2500 _DOES NOT_ support HST. You have to be aware of this. The current Telebit modems are: Trailblazer Plus PEP T1000 PEP at 9600bps T1500 V.32 T2000 PEP and SNA/HDLC T2500 PEP, SNA/HDLC, and V.32 As far as I know, all PEP modems support protocol spoofing--XMODEM, Kermit, UUCP. Currently, all V.32 supported Telebits sports V.42/V.42bis. There are Trailblazers for cellular phones, but I don't know too much about them. >So I can use the (external?) T2500 and talk to any modem known to man? > No. [I almost wanted to comment that PEP and HST are primarly half-duplex while V.32 is full duplex; but apparently there's been some really hot debate whether this is true for the HST on another network. Can anyone who is qualified post the answer? It's true that the HST is full duplex, but transfers data asymmetrically. I suppose my question is: "When one says 'full duplex,' does it automatically imply symmetrical full duplex IN THE TELECOMMUNICATIONS WORLD?" i.e. When one says "I'm going to build a new type of full duplex modem," do all engineers think it's symmetrically full duplex without further inquery? Or does one have to specify symmetrical full duplex to imply symmetrical full duplex?] > >Thanks! > >Carra Bussa @ cup.portal.com > Ken I have no connection with Telebit other than a satisfied customer. -- _____________________________________________________________________________ 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
tempest@wet.UUCP (Ken Lui) (08/17/90)
In article <1458@wet.UUCP> tempest@wet.UUCP (Ken Lui) writes: >there's the T2000 that also supports SNA/HDLC connections. The ^^^^ > T2000 PEP and SNA/HDLC ^^^^ > T2500 PEP, SNA/HDLC, and V.32 ^^^^ Oops, that should have said SDLC. Sorry about that. Treats me right for not using it and to go ahead and comment on it... 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
tnixon@hsfmsh.UUCP (Toby Nixon) (08/18/90)
In article <32867@cup.portal.com>, Carra_its-me_Bussa@cup.portal.com writes: - I'm planning on getting a high-speed modem. There SEEM to be 3 types: - - USR HST modems using MNP 5 (giving 19.2) - v.32 modems using v.42bis (Hayes V-series & others) - Telebit PEP modems Actually, there are several other types of 9600bps modems. There are only two international standards: V.29, which is half-duplex on dial-up lines and full-duplex on four-wire leased lines, and used for Group 3 fax transmission; and V.32, which is asynchronous or synchronous full-duplex on two-wire dialup or leased lines. There are a plethora of proprietary modulation schemes, including Hayes V-series fast-turnaround ping-pong, Telebit DAMQAM multicarrier, USR HST assymetrical, Microcom MNP6 (which is fast-turnaround V.29), Racal-Vadic 9600VP (which is 2400bps duplex with switching into V.29 slow-turnaround half-duplex as required), EVI Fastcomm (a different asymmetrical scheme), etc. - HST (5+) uses compression to increase their speed over the single - carrier. The HST uses an asymmetrical scheme with real 14,400bps modulation in the forward direction and 450bps in the reverse direction. It's OK for file transfers, but not that great if you're changing the direction of the line very often (especially echoing). They also support compression on top of this. The USR Dual Standard also has V.32 modulation. - V.32 runs at 9600 FDX, w/v.42bis to double it's speed over the - single carrier. V.32 is 4800 or 9600 duplex. V.42bis data compression can quadruple throughput, depending on the data you're sending. - PEP uses multiple carriers (unlike Hayes/USR HST) and can slowly(?) - lower the baud and/or change working carriers as the line - changes. PEP is the error control protocol used in Telebit modems; DAMQAM is the modulation scheme. The point is not that it "slowly lower[s] the [bps] rate", but that it measures the quality of the circuit and assigns power and bits to each carrier depending on the measured capacity of that portion of the channel. The increments of degradation are smaller, but not necessarily the speed at which changing line conditions are recognized (line conditions changing very rarely during the course of a connection). - USR has the dual v32/HST modem; Hayes has the Ultra modem. Both of - these do MNP5 and v.32, and can talk to each other (right?) Right. The currently-shipping HST Dual Standard also does V.42bis, so you can get 38,400bps throughput between it and an Ultra 96. - The telebit modems use PEP, but the 1000 is PEP 9600, the + is - 9600/v.32, and the 2500 is PEP/v.32/HST (?) (MNP 5??) I think it's the 1500 that is V.32-only. The 2500 DOES NOT have HST asymmetrical modulation, just DAMQAM, V.32, and the lower speeds. - So I can use the (external?) T2500 and talk to any modem known to - man? No. It won't talk in high-speed mode with modems from other manufacturers that have only their proprietary modulation scheme. You'll only be able to talk to modems that also have V.32. Fortunately, that number is growing; virtually all manufacturers I've mentioned above now have modems that support both their proprietary schemes AND real CCITT V.32 modulation. - Just trying to get my facts straight before I plunk down a megagram - of pennies Somehow, I think you'll be due change back from 2,200 pounds of pennies, regardless of which modem you buy! :-) -- Toby ----------------------------------------------------------------------------- Toby Nixon, Principal Engineer Fax: +1-404-441-1213 Telex: 6502670805 Hayes Microcomputer Products Inc. Voice: +1-404-449-8791 CIS: 70271,404 Norcross, Georgia, USA BBS: +1-404-446-6336 MCI: TNIXON Telemail: T.NIXON/HAYES AT&T: !tnixon UUCP: ...!uunet!hayes!tnixon Internet: hayes!tnixon@uunet.uu.net MHS: C=US / AD=ATTMAIL / PN=TOBY_L_NIXON / DD=TNIXON -----------------------------------------------------------------------------
larry@nstar.uucp (Larry Snyder) (08/19/90)
Carra_its-me_Bussa@cup.portal.com writes: >OK gang, I'm dumb. I'm trying to decide which high-speed modem to buy. >I'm looking at 3 modems in particular: >brand "street prices" who >Hayes Ultra $900 (PC Connection (the raccoon people)) >USR HST Dual $1000 (PC Brand) >Telebit T2500 $870 (AnDATAco) I guess it depends on who you plan to communicate with - We have the Hayes V.42, USR HST and Telebit T2000 here at NSTAR - none of the modems have V.32 - but other than that we cover most bases. All the high speed news connections are on the PEP and Hayes V.42, while the HST and Hayes V.42 also support the BBS users (DOS users) and the Unix BBS users call in on the PEP. Your price for the T2500 is excellent! -- Larry Snyder, Northern Star Communications, Notre Dame, IN USA uucp: iuvax!ndmath!nstar!larry -or- larry@nstar Public Access Unix Site (219) 289-0282 (5 lines/PEP/HST/Hayes-V)