jsq@im4u.UUCP (John Quarterman) (11/15/85)
This is a survey on 2400 baud or faster modems, as subject
which should be of interest to many, considering the increasing
traffic on both the UUCP and USENET networks, and the lessening
ability of a few sites to handle major parts of the load for the rest.
If someone has done such a survey recently, please just tell me.
In any case, please *MAIL*, do NOT post, all responses and I will summarize.
This is especially important since some of the newsgroups
I'm posting to may or may not be appropriate.
Your name and address will be included in the summary unless
you explicitly state otherwise in your response.
What I'm interested in are 2400 baud modems which can be used
to run UUCP or SLIP (TCP/IP over RS232). Faster modems are also
of interest, though it's not clear we can afford to buy any.
However, they must run over unconditioned telephone lines.
Asynchronous preferred.
Specific information of interest:
What modems you use, and for what (UUCP, USENET, terminal dialup, SLIP, etc.).
What other modems you know of.
For each modem model:
Manufacturor's name, telephone number, and address.
Same for distributor, if different from manufacturor.
Date available, model number, autodial, speeds, synchronous/asynchronous.
Rack mount or other.
Price, and discounts (bulk, academic, other).
What other modems they are compatible with:
since there seem to be at least two different 2400 baud standards,
this is of particular interest. If someone could send me a brief
summary of the various standards in use, that would be a big help.
Any other comments you'd care to add.
Remember: MAIL, do NOT post news! I will summarize.
Your name and address will be in the summary,
unless you explicitly tell me not to put it there.
Thanks.
--
John Quarterman, UUCP: {ihnp4,seismo,harvard,gatech}!ut-sally!im4u!jsq
ARPA Internet and CSNET: jsq@im4u.UTEXAS.EDU, formerly jsq@im4u.ARPAjsq@im4u.UUCP (John Quarterman) (11/24/85)
>From: jsq@im4u.UUCP (John Quarterman) >This is a survey on 2400 baud or faster modems, as subject >which should be of interest to many, considering the increasing >traffic on both the UUCP and USENET networks, and the lessening >ability of a few sites to handle major parts of the load for the rest. This summary was prepared by Carol Kroll, who didn't realize beforehand what she was getting into. A couple of disclaimers to add to what she writes: The set of newsgroups being posted to here may or may not be appropriate. If not, sorry about that, but remember that at least B news only transfers one copy and uses links. Some of the responses arrived as inclusions inside responses from other people, as they had evidently been responses to earlier surveys. Due to time constraints, we have not been able to ask permission to post every such included letter, and have assumed that you wanted your letter public. On to Carol's summary. -jsq Our thanks to everyone who replied to this survey. It turns out that an information summary on these modems is already available, in an article by Brian Edwards in the October 1985 issue of Hardcopy (Vol. 14, No. 10). It includes an 8 page chart describing the interface, protocols, jacks, features, and price of over 60 different manufacturers' 2400 baud modems. There appear to be a few inaccuracies, but the list is certainly helpful. Missing from the Hardcopy list are the USR Courier 2400, CTS Datacomm 2424AD, and Electronics Vaults UPTA-96/S. Information on them follows. The CDS 224 is in the article, but the info Tim Radzykewycz sent is more complete, and is also appended. This is the first of four messages. The others are: (2) a reposting of a description of 2400 transmission protocol types and standards by Bob Cunningham of Hawaii Institute of Geophysics from May 85, (3) a summary of comments people sent about their experience with the USR Courier 2400, (4) summary of comments on other types of modems. Manufacturer USRobotics Distributor Tek-Aids 1400-A Smith Rd Austin, TX (512) 385-0590 Modem Courier 2400 Interface RS232 Price 440.00 Baud or bps 300/1200/2400 Protocols Bell103/Bell212A/CCITT V22.bis Housing Standalone Autodial? yes Asynchronous? yes Public switched tele. network? yes Warranty 2 years Other autobaud in answer mode Manufacturer CTS Datacomm (203) 743-3681, Pete Coccaro Distributor Hall-Mark Electronics 12211 Technology Blvd Austin, TX 78727 (512) 258-8848 Modem CTS-2424ADA (CTS-2424AD rackmount) Interface RS232 Price 315.00 (495.00) Baud or bps 300/1200/2400 Protocols Bell103/Bell212A/CCITT V22.bis Housing Standalone (card) Autodial? yes Asynchronous? yes Public switched tele. network? yes Warranty Other autobaud in answer mode 16-card rack is $795.00 stores 10 numbers >From: ut-sally!seismo!gould9!sdcc3!ucbvax!calma!radzy (Tim Radzykewycz) CDS: manufacturer: Concord Data Systems 303 Bear Hill Road Waltham, MA 02154 (617) 890-1394 telex 95-1793 distributor: We used: Electro-Data Marketing 552A Valley Way Milpitas, CA 95036 (408) 945-1300 available: currently model number: 224 Autodial Modem autodial: yes speeds: 1200/2400 synch/asynch: asynchronous housing: standalone price: $689 on 3/85 discounts: unknown compatibility: 2400: ccitt v.22bis 1200: bell 212 let me quote the manual here: ...conforms to the following recommendations: o EIA RS232, RS422 o CCITT V.24, V.28, V.54, V.22bis (at 2400bps) o ISO and IEC specifications relevant to data modems and interfaces o Bell 212A (1200bps mode only) use: These modems are only used for dial-in. Right now, we are receiving UUCP (from SUN) calls and interactive use from home. comments: 1. These modems do not have fuses. We recently had one die because of this. I returned it a week ago, and it is not back yet. 2. The command set is non-hayes compatible. This is not so good for uucp dial-out, but fine for dial-in. There were some requests out a while ago in net.wanted for uucp drivers for these beasts, but I didn't grab them. I think the command set is better than Hayes. ************************************************************ manufacturer: Electronic Vaults, Inc 12347-E Sunrise Valley Drive Reston, VA 22091 (703) 620-3900 distributor: direct from mfg available: currently model number: UPTA-96/S autodial: yes speeds: 4800/7200/9600 synch/asynch: asynchronous housing: standalone -- Also available in IBM-PC version. price: $995 on 8/85 ($895 for PC version) discounts: unknown compatibility: none use: We have one set up for dial-in on one of our machines, and the other is used from home for dial-in. We plan to test this out for uucp, but haven't done so yet. comments: 1. This is a half-duplex modem, and it takes a significant amount of time to switch transmission directions. This makes it somewhat poor for interactive use. 2. We've had some problems with keeping the lines up. Every once in a while, the modem I have at home will print the message "OK\nRING\n", and disconnect you. Electronic Vaults has sent me new ROMs, but I haven't yet installed them. 3. They are very reliable, except for the above problem. I have *never* gotten a "noise" character with these. -- John Quarterman, UUCP: {ihnp4,seismo,harvard,gatech}!ut-sally!im4u!jsq ARPA Internet and CSNET: jsq@im4u.UTEXAS.EDU, formerly jsq@im4u.ARPA
jsq@im4u.UUCP (John Quarterman) (11/24/85)
The comments in square brackets in the following article were there when we got it: they aren't by me or Carol. Thanks to Bob Cunningham for the original posting: hope you don't mind the reposting. -jsq >From bob@islenet.UUCP (Robert P. Cunningham) Wed May 8 18:25:37 1985 Path: ukma!cbosgd!ihnp4!mhuxn!mhuxr!ulysses!allegra!mit-eddie!genrad!decvax!ittvax!dcdwest!sdcsvax!noscvax!uhpgvax!islenet!bob >From: bob@islenet.UUCP (Robert P. Cunningham) Newsgroups: net.dcom, Subject: 2400 bps modems can be non-standard Message-ID: <1097@islenet.UUCP> Date: 8 May 85 22:25:37 GMT Distribution: net Organization: Hawaii Institute of Geophysics Lines: 112 [These are my notes on some problems with U.S.-made 2400 bps modems, using information from a variety of different articles and discussions with various vendors. Clarifications and corrections welcome.] 2400 bps modems. Twice the throughput of 1200 bps modems for less than twice the price. It sounds good, but many of the new 2400 bps modems now on the market in the U.S. are not completely compatible with similar models from other manufacturers. There is no U.S. asynchronous dial-up 2400 bps standard in the same sense that the Bell 212 modem set the standard for 1200 asynchronous modems. There are two European standards: "CCITT V.22 bis" and "CCIT V.26 ter". These are written standards, while the Bell 212 was a complete working product, with very well known operating characteristics. A minor difference in principle, but a tremendous difference in practice. Not only are there loopholes in the CCITT standards that give each manufacturer considerable room to be creatively different, but there are some modifications that U.S. manufactures tend to make in order to maintain some compatiblity with existing U.S. equipment. The result is that many of the 2400 async dial-up modems are incompatible with each other in various ways. Most of the new U.S. made 2400 bps async dial-up modems follow the V.22 bis standard. They transmit and receive simultaneously by splitting the available bandwidth in half, using half to receive and the other to transmit, with a 16 point Quadrature Amplitude Modulation (QAM) technique at 600 baud [precisely speaking, the baud rate is the rate of change of the signal ... QAM and most other techniques provide a way of encoding several bits into each change of the signal]. A few use an alternate CCITT specification -- V.26 ter. Signal cancelling (the receiver cancelling out the echo of its own transmitted signal) allows the whole bandwith of a phone line to be used. V.26 ter uses a Differential Phase Shift Keying technique to handle 2400 bps at 1200 baud. V.22 2400 bps is probably less reliable than 212-type 1200 bps over long-distance lines, V.26 ter is probably better than 212. Of course V.22 bis and V.26 ter are completely incompatible. While V.22 bis seems to be the preferred standard now, there is a good chance it may eventually be superseeded by V.26 ter. [Then again, maybe not; the Vadic 1200 bps technique is -- in some ways -- more effective than 212, but it's never really caught on.] Now, about those loopholes in V.22 bis ... The standard designates a fall-back speed, if the originate and answer modems can't handle a 2400 bps connection. However, the standard doesn't specify how the connected DTE equipment (computer or terminal) is to be notified of the fall-back. The RS232C standard doesn't cover it. With V.22 bis, each U.S. manufacturer seems to have chosen a DIFFERENT way of indicating a speed change when the modem falls back, using various of the seldom-used secondary control pins on the RS232C connector. Chances are that the typical DTE device you hook up your 2400 bps modem to will ignore the speed change signal. Then, when you obtain a dial-up connection that's a bit noisy, the modem falls back. It sets up and maintains the connection nicely, but not at the baud rate your computer or terminal expects. This can tie up the equipment at each end indefinitely. V.22 bis specifies the CCITT V.22 format for 1200 bps fallback. Unfortunately, that's incompatible with Bell 212. To allow V.22 bis modems to be used together with regular 212 modems, many (but not all) of the U.S. manufacturers have chosen to make 212 rather than V.22 the fallback. As a convenience, some (but, again not all) of the U.S. makers who provide 212-type 1200 bps fallback also provide a further 103-type 300 bps fallback from 1200 bps. Nice feature, but definitely not in V.22 bis. There's still another common "Americanization" that U.S. manufacturers have adopted. V.22 bis assumes that the European standard 2,100 Hz answer tone be sent by the answering modem during initial connection handshaking. Many U.S. manufacturers have instead adopted the regular U.S. 2,225 Hz answer tone -- again for 212-type compatibility. Unfortunately, this means that many U.S.-made V.22 bis modems won't handshake at all with a European V.22 bis modems. V.22 bis specifies V.25 (or V.25 bis) autodialing. U.S. makers prefer their own variation of the Hayes autodialing commands (or the Concord technique, or the AT&T technique, or Cermatek ... there's definitely no effective U.S. standard for autodialing commands). Summary & recommendations: If you want a 2400 modem that will talk to European-made modems make sure it uses the 2.1 kHz answering tone, and has V.22 (not 212) fallback. Find out whether the other end uses V.22 bis or V.26 ter. If you need point-to-point 2400 bps dialup in the U.S., choose your favorite manufacturer, but you'll have more consistent results of you have the same model from the same company at the other end. Otherwise, don't be surprised when your modem "hangs". In any case, may expect to see more "phone line hits" -- especially over long-distance lines -- than you get with your 1200 bps modem. -- Bob Cunningham ..{dual,ihnp4,vortex}!islenet!bob Honolulu, Hawaii -- John Quarterman, UUCP: {ihnp4,seismo,harvard,gatech}!ut-sally!im4u!jsq ARPA Internet and CSNET: jsq@im4u.UTEXAS.EDU, formerly jsq@im4u.ARPA
jsq@im4u.UUCP (John Quarterman) (11/24/85)
In response to this survey there were many comments on the USR Courier 2400 modem, which are summarized below: >From ut-sally!seismo!gould9!sdcc3!ucbvax!calma!radzy Sun Nov 17 07:54:54 1985 USR: manufacturer: US Robotics 8100 North McCormick Blvd. Skokie, IL 60076 distributor: We used: Electro-Data Marketing 552A Valley Way Milpitas, CA 95036 (408) 945-1300 available: currently model number: Courier 2400 autodial: yes speeds: 300/1200/2400 synch/asynch: asynchronous housing: standalone price: approx $600 on 3/85 discounts: unknown compatibility: I can't find any protocols in the manual, however, it talks with the CDS modem (and I presume Hayes 2400). use: These modems are used for people to log in on. They are only used for interactive use from home. comments: 1. Some early models had non-working ROMs in them. We got one of these. The fix is simple. 2. We're reasonably happy with these. ************************************************************ Tim (radzy) Radzykewycz, The Incredible Radical Cabbage calma!radzy@ucbvax.ARPA {ucbvax,sun,csd-gould}!calma!radzy >From: W8SDZ@SIMTEL20.ARPA (Keith Petersen) The following review was not written by me. It was downloaded from a Remote CP/M system. Unfortunately there is no way to reach the author because it is unsigned. It is presented here for its possible informational value. Please address discussions/comments to the mailing list, not me. I don't own a 2400 baud modem. --Keith 10 Mar 85 ... 2. USR COURIER 2400 The USR Courier seems to be the first smart low-priced modem to be released, probably due to the fact that, unlike many manufacturers, it does not use the Rockwell chip set. It features Hayes 2400 compatibility. I will briefly summarize the positive aspects of the modem: - externally accessible, well-labeled configuration switches - external switch to reverse pins 2 & 3, thus eliminating the need for a null modem - result codes can be completely turned off via switch - volume control for internal speaker After setting the configuration switches (an easy task for anyone who has ever set up a modem) the Courier is ready for operation. With the appropriate switch setting, it can be used both in originate and answer mode without any hardware changes. Originating a call can be accomplished with the now-famous ATDT sequence, except that command letters no longer have to be in caps. As with other smart modems, any character typed while dialing or waiting for carrier aborts the action and hangs up the line. The "escape" character can be used to either return the modem to command mode (like the Hayes) or to hang up (like other USR modems) depending on a configuration switch setting. The Courier was used to successfully connect to the local TYMNET number. A later model also was able to talk to a VADIC 2400 baud unit over long distance (Wayne Masters' RCPM). The Courier was also able to call and be called by a Penril 2024 and another Courier. As to autoanswer mode, the modem was a complete washout to put it mildly. Surely, hard- and software are partly to blame but the fact that other modems (including USR Password and AD212A) work with the same setup indicates a serious flaw in the Courier. The hardware used, for whatever reason, drops DTR while changing baud rates. The duration is so short that all other modems tested on the hardware, EXCEPT the Courier, are totally unaffected. The Courier will, upon carrier lock and receipt of the first character typed, drop the carrier 3 out of 4 times at 1200 and 2400 baud. While no considerations were given to 300 baud performance, it was noted that those problems only exist at 1200 and 2400 baud. Placing a 5MFD capacitor from the DTR line to ground totally fixed this problem. In autoanswer mode, the modems were used as follows: - all result codes are inhibited - on carrier loss, computer reboots, cycles DTR, then waits for a character typed by constantly polling the data input port - on receipt of character, baud rate is tested and, if necessary, changed I must again stress that this method works with all modems tested. The USR Courier, however, would simply refuse to answer any more phone calls after answering a few. No set pattern was discovered. Sometimes, the modem would work properly for 5-10 calls then refuse to answer, at other times it would only allow 1 or 2 calls. When it refused to answer, no outside indication was given as to the problem. The appropriate LEDs on the front panel were lit yet the modem did not respond to the ring. Surely, this is a most serious deficiency and I have decided that the Courier is unfit for use in this particular application. I am convinced the problem lies solely with the Courier, particularly sonce both the Auto Dial 212A and the Password 1200 work in the exact same environment (except for the much-needed 2400 capability, of course). In closing I must again stress that the USR certainly is a superb modem and very well suited to originate applications. Considering that 99 out of 100 modems sold will never be used for pure autoanswer purposes, the Courier is not at all a failure. One modem was tested in late November, two in late February (both were preproduction units) and thre PRODUCTION units were tested in March. All five units exhibited the same problems. ...may those who have the power to change things do so, may those whose toes I stepped on test for themselves before stepping on mine, may those who want to buy a Courier not be discouraged. If YOU intend to use a USR Courier in an autoanswer-only environment, please by all means give it a try, it may sure work for you. If it doesn't, you have been warned, and if it does, either "they" fixed it or the problem is installation-dependent... >From ut-sally!topaz!packard!cbosgd!rice!neuro1!sob Mon Nov 18 14:17:05 1985 I have sent you all I have, hope it is helpful. >For each modem model: >Manufacturor's name, telephone number, and address. USR ROBOTICS, 8100 North Mc Cormick, Skokie,IL 60076 They have an 800 number, but I don't have it handy. >Same for distributor, if different from manufacturor. See enclosed text to follow >Date available, model number, autodial, speeds, synchronous/asynchronous. They are currently available, Courier 2400, Hayes command set auto dial, 300 (103), 1200 (212A), 2400 (CCITT V.22bis), asynchronous only >Rack mount or other. stand alone only >Price, and discounts (bulk, academic, other). We got ours for $399 from a particular distributor that seismo recommended. >What other modems they are compatible with: They work with the Hayes 2400 and all the 1200's I have do uucp with. (RIXON R212A, Hayes 1200, Cemetek Info-mate) Please let me know your thoughts if any about this topic. ------------------------------------------------------------------------ >From USENET, by Rick Adams <seismo!rick>: I have spent the last 2 weeks evaluating a US Robotics Courier 2400 modem. I have beat on it pretty severely and can't find anything wrong with it. We are buying several. I like it well enough that I will probably buy myself one for home use. The modem was used for uucp traffic on seismo for 2 weeks. It was used for both dialins and dialing out. The ONLY problem I could find with it is that if you try and call another site at 2400 baud and it can only sync up at 1200, the modem prints "CONNECTED 1200" and then resets the baudrate to the host to 1200 baud. I added 5 lines of code to the dialer in uucp and have had no problems since. I consider this to be minor. Anyway, on to details. The GSA cost is $399 quantity 1. If you are not on the GSA scale (i.e. if you don't buy as a US government agency), you can still get it at this price by mentioning you heard about this price from The Center for Seismic Studies (i.e. where I work). The list price on this model is $895 and the regular non-GSA price is $479 (other dealers may charge more). The modem operates at 300/1200/2400 baud (Bell 103/Bell212A/CCITT V22.bis) in both originate and answer mode. It will fall back to 1200 from 2400, but not from 1200 to 300 in orignate mode and correctly autobaud in answer mode. A nice (and undocumented feature) is that the modem will detect what baudrate the computer is sending at and use that as the dialout speed. This means you can just list the same modem in your L-devices file 3 times with different speeds and not change anything else. [it's simpler than it sounds if you are confused] In orignate mode, it will detect (with a serate message for each) ringing, busy, dialtone, and voice (and hang up on a voice). It uses a superset of the HAYES SMARTMODEM command set. I used the unmodified Hayes driver for a while before changing it to also handle the USR extensions. It also claims to be able to be used with CrossTalk, SmartCom and PC-Talk communications software, but I was unable to test this. (I presume it will work, as it looks like a hayes) It does pulse or tone dialing and if tone dialing doesn't get rid of the dialtone, it will try pulse dialing. The warranty is 2 years from US Robotics. The dealer will also handle warranty repairs (by sending you a working one and sending yours off to the factory.) The 1200 baud performance was much, much better than our Racal-Vadic MACS dialers. We were able to connect to sites with the USR modem that we could not get to with the Vadic modem. There was very little noise at 2400 baud and virtually none at 1200. I successfully connected at 2400 baud to ATT, Concord Data Systems, Vadic and USR 2400 baud modems, so there is no interoperability problem. This also worked at 2400 baud on our ITT WATS lines which are much, much noiser than ATT WATS (then again, they are also much cheaper, you get what you pay for). I expected it to have problems with the noisy ITT lines, but it worked perfectly. I wasn't able to give it the acid test of trying to use Sprint, but then nothing works on Sprint reliably... Physically, it's 6" x 10" x 1". It's a very nice, low profile modem. The dealer is the major east cost distributer for US Robotics and has many units in stock. We received ours within days of placing the order. The $399 price is ONLY available from the following dealer. Any other dealer will probably charge you more. The dealer is: Advanced Data Products, Inc. 18974 Bonanza Way (B-3) Gaithersburg, MD 20879 (301) 424-9490 The salesmans name is: Don Parnell You can probably pay for the cost of the modem in the savings in a few months phone charges. It sounds too good to be true, but I've got a couple in the computer room proving they are real. rick@siesmo.uucp >I resently posted an inquiry about "inexpensive" modems, because we wanted to purchase several. These are the responses I received from the inquiry. I want to thank all the folks who responded. It helped us a great deal in making our selection. Thanks, David C. Bennett SCI Systems, Inc. {decvax, akgua}!mcnc!rti-sel!scirtp!dcb From: rti-sel!mcnc!ulysses!t12tst!chip (Chip Rosenthal) I've got a pair of USR 2400 modems, I'm pretty happy with. I've been using them for a lot of talking with another site about 120 miles away. They have worked very well when the other site uses USR 2400's. However, when the other place had Hayes 2400 I couldn't get a 2400 baud connection. I suspect the Hayes, but I don't have one in-house to play with. Complaints: 1) the DIP switches are underneath. Real pain when you have six modems stacked up in the bowels of a VAX like I do. You can't see or set switches without pulling the whole fricking thing apart. 2) the volume control is a slide control with a press-on knob. i've knocked it off before. 3) i can't figure out any reasonable way of dealing with a lot of them due to their packaging and those %*^$@$# power supply transformers all modem manufacturers seem to use. about all i can see is that you stack them, dangle cords all over the place, and hope that you've got enought AC outlets for the transformers. 4) One of our two modems arrived DOA. Repair went OK. Took about two weeks, which I suppose is reasonable, but I would have been much happier if the distributor appologized profusely and gave me a brand new one immediately. In spite of all these things, I would have no qualms buying them again. This might suprise you, but the problem which irks me the most is #3. If I could find a good way of storing these turkeys it would keep #1 and #2 from being intolerable. I'm willing to chalk #4 up as bad luck and catagorize it as reasonable response. What is good about them is that they seem pretty noise tolerant, they seem to establish connection and baud rate reliably. It has two commands I really like. The ATX6 tells me what is going on with the modem. BUSY, RINGING, etc. The answer I like best is VOICE. That's always good for a moment's panic. (Especially when I'm doing my dialing at 1:30am.) Also it has a command to display the current settings, which is obviously useful. (It impressed me, but then again I'm used to working with Hayes 1200's). Is there a reason why you aren't considering Hayes 2400, besides cost? Do you know something I don't? (PS. I wouldn't mind being forwarded a copy any interesting messages you might receive.) -- Chip Rosenthal, Intel/Santa Clara, (408) 496-7651 {intelca,idi,qubix,cbosgd}!t4test!chip -------- Stan uucp:{ihnp4!shell,rice}!neuro1!sob Opinions expressed Olan ARPA:sob@rice.arpa here are ONLY mine & Barber CIS:71565,623 BBS:(713)660-9262 noone else's. -- John Quarterman, UUCP: {ihnp4,seismo,harvard,gatech}!ut-sally!im4u!jsq ARPA Internet and CSNET: jsq@im4u.UTEXAS.EDU, formerly jsq@im4u.ARPA
jsq@im4u.UUCP (John Quarterman) (11/24/85)
Here's what's left. Be sure to notice the date on each message before depending on it for ordering information. Some of these are a year old. One is the oft-quoted survey of December 1984 from Bruce Factor. It's reposted here in the interests of reducing the number of times it gets mailed around from person to person. Not to mention historical interest: prices on 2400 baud modems have dropped by half within a year. >From ut-sally!topaz!packard!cbosgd!ukma!david Mon Nov 18 13:35:09 1985 Date: Sat, 16 Nov 85 10:48:17 est From: ut-sally!topaz!packard!ukma!david (David Herron, NPR Lover) Subject: Re: 2400 (or higher) baud modems To: im4u!jsq Newsgroups: net.periphs,net.news,net.lan, The following are messages I've been collecting about 2400 baud modems. We have 4 Multi-Tech 2224's here. They were selected by the person we feed in Cincinnati after he looked at all the modems he coiuld get his hands on. These modems do NO error correction protocols, which was a conscious decision because he was having terrible problems with the ones that did do error correction. Date: 20 Dec 1984 06:52 MST (Thu) >From: Keith Petersen <W8SDZ@SIMTEL20.ARPA> To: Info-Cpm@AMSAA, Telecom@MIT-MC Subject: 2400 baud modems This is file 2400BAUD.TXT - relayed from the RCPM circuit: --Keith >From: Wayne Masters, Potpourri sysop (408) 378-7474 300/1200/2400 baud San Jose, Ca. Subject: New 2400 baud modems 8/19/84 Many of you have asked technical questions about the 2400 baud modems now on the market (and more being introduced monthly). As most of you know by now Irv Hoff and I have been beta testing 2400 baud for several months. The test results are amazing to say the least. Running controlled tests on standard dial-up phone lines with random "noisy connections", the number of "hits" on a given file transfer is less by a factor of 10 using 2400 baud vs 1200 baud. So it is concluded that 2400 baud technology is working and will soon be available on most commercial and private dial-up systems. Now, what is a "standard" 2400 baud modem? You will no doubt see various technical descriptions of a given 2400 baud modem touting it's features. Be sure the modem you choose has this specification: CCITT recommendation for a V.22 bis modem communicating at 2400 bps. Further explanation of this CCITT standard: Frequency- Bell 212A Encoding modulation- 16 level psk (quadrature AM or QAM) This sounds a lot like the Bell 212A standard for 1200 baud--and it is. The difference is in the encoding or modulation scheme. Bell 212A 1200 baud uses 4 level psk and 2400 baud uses 16 level psk. If you "listen" to the 2400 baud carrier it will sound exactly like the familiar 1200/212A- like "static" or a scratchy noise. Features to look for in your search for the "right" 2400 baud modem: 1. Does it retain 300 baud bell 103 capability? (most offer 1200 baud as a "fallback") 2. Is it "smart"--a biggy if you intend to call other systems a lot. 3. Does it offer autoanswer--a biggy if you run a remote system. 4. Price--a real biggy So far, none of the modems on the market offer all these features in a "standalone" modem. That is one big reason why Irv Hoff and I have been involved with Racal-Vadic--not only beta testing to prove 2400 baud technology...but to get the features most users prefer designed into the modem. Others may follow some day but Racal Vadic will introduce their "standalone" modem in time for Christmas 84 with the following features: 1. Smart-autodialing. It will recognize both the Hayes and Vadic commands. 2. 0-300 baud at both Bell 103 and Vadic protocols 3. 1200 baud at both Bell 212A and Vadic protocols 4. 2400 baud CCITT V.22 bis 5. Price is expected to be $695.00 retail The first release will be an external RS-232 model. Early 1985 will see the single card slot version for IBM PC's and compatiables. In order for 2400 baud to be in "great demand" there must be systems available for the users to access. I am working with Racal-Vadic to identify RCP/M and RBBS systems where 2400 baud modems could be placed to generate public interest in 2400 baud. Sysop's should contact Potpourri at 408-378-7474 if interested in participating. Now about software to support 2400 baud. Both MDM7 and MEX will support 2400 baud if the user modifies his port overlay to setup his port for 2400 baud. For sysops who use BYE3, the problem is different. Most implementations of BYE rely on the hardware's Data Available signal (DAV) to trigger a check-for-carriage-return sequence at different baud rates. If most hardware is like mine (Z80 SIO), if the hardware is set to look at 300 baud and the modem answers at 2400 baud the DAV is never set and you are in an endless loop. Same thing happens if you set the hardware to 2400 and the modem answers at 300. I modified BYE3 (version 26 and up) to handle TSTBAUD differently. I chose to look at each baud rate in 2 second windows, 300 first, then 1200 and 2400, and loop thru this sequence until a C/R or L/F is detected. The caller is never more than 4 seconds away from his calling speed but must continue to issue c/r's until the familiar message "Nulls, if needed" is displayed. Sysop's who choose to use BYE3 need only add the "SET2400" code into their port insert. Well, enough for now. Feel free to contact me if you are more confused now than you were before reading this. -wayne masters, Potpourri sysop- 408-378-7474 ------------------------------ End of TELECOM Digest ****************************** Path: ukma!qusavx!hasmed!cbosgd!ihnp4!houxm!whuxlm!harpo!decvax!genrad!mit-eddie!godot!harvard!seismo!brl-tgr!tgr!philabs!sbcs!bruce%cmcl2.uucp@Seismo.ARPA >From: bruce%cmcl2.uucp@Seismo.ARPA Newsgroups: net.micro.cpm Subject: 2400 baud modems Date: Thu, 27-Dec-84 09:16:05 EST For those of you in the market to buy 2400 baud modems I want to inform you of a great deal. I would like to state that I am not affiliated with ANY of these companies, and I am not receiving and benefits by posting this information! After spending a few days pricing modems I have compiled the following information (saving the best for last). If anyone has any additional information I would greatly appreciate it. We were interested in rack mounting them so most of the prices given are for cards that would plug into a rack. "box" refers to a stand alone modem. DEC 1 - (800) 962 - 3244 now DF112-AM 300/1200 card $ 506 now DF126-AM 2400 only card $ 634 Racal Vadic 1 - (800) 482 - 3427 now VA212PAR 300/1200 card $ 445 3/85 VA4224 1200/2400 card $ 740 now VA1681 houses 16 rack $ not priced yet Concord Data Systems (617) 890 - 1394 Q10-24 now CDS224 AA/ORG 1200/2400 box/card$ 845 $ 825 now CDS224 Autodial 1200/2400 " $ 995 $ 975 now CDS224 ARQ 1200/2400 " $1295 now CDS224 ARQ Auto 1200/2400 " $1395 now CDS224 Super 1200/2400 " $1695 now CDSRM-07A houses 7 rack $ 750 Hayes 1 - (800) 241 - 6492 now Hayes1200 300/1200 box/card$ 499 2/85 Hayes2400 300/1200/2400 box/card$ none now 08-00056 houses 6 rack $ 766 Quantity Discounts are minimal. Micom 1 - (800) 527 - 0204 Q >16 now M3012 300/1200 box $ 495 now M3012 plus 300/1200 box $ 595 1/85 M3024 1200/2400 box $ 795 1/85 M3024 plus 1200/2400 box $ 895 $ 805 " " " card $ 845 $ 760 now M3200 houses 16 rack $ 750 General Datacomm (203) 574 - 1118 Q 10 - 19 now DC211AL 300/1200 box $ 675 $ 595 " " " card $ 585 $ 520 1/85 DC2412 1200/2400 box $1195 $1050 " " " card $1105 $ 790 " DS1 houses 16 rack $ 795 Paradyne 1 - (800) 482 - 3333 or 1 - (800) 342 - 3532 now DTU1200D 300/1200 $ now 1200/2400 $ 900 NEC 1 - (800) 538 - 8166 Q 11 -20 now N212BRL 300/1200 box $ 795 $ 669 " " " card $ 725 $ 606 " DSP2430 1200/2400 box $1095 $ 976 " " " card $ 965 $ 855 " N4083 houses 8 - 1200 rack $ 625 " SR0801 houses 8 - 2400 rack $ 900 QUADRAM (404) 923 - 6666 Q > 3 now QM10000 300/1200 $ 695 $ 625 not available ?/2400 $ NO Rack mounting. Ven-Tel 1 - (800) 538 - 5121 Will Call me back. 300/1200 $ ?/2400 $ Promethus (415) 490 - 2370 (check 800) Distributor: Will call me back. 300/1200 $ ?/2400 $ Fujitsu (408) 946 - 8777 ext 576 not available 300/1200 $ now F1935B 1200/2400 $ 895 ------------------------------- CTS Datacomm (203) 743 - 3681 Pete Coccaro Distributor: Professional Network Services Harvey Schlesinger (617) 449 - 6460 Model: CTS2424AD These people had by far the best deal. The list price for the Stand Alone (box) modem is $ 795 The list price for the (rack) mounted modem is ~$ 700. Besides starting off $ 200 less than everyone else their quantity discounts are very good. The Stand Alone modem will be available starting January, and their rack mount modem should be available February. Here is a Quantity discount price list. Quantity %dicount S.A. rack ======== ======== ==== ==== 1 list $795 $700 2-5 10 % 716 630 6-10 20 % 636 560 11-25 25 % 596 525 25- 30 % 556 490 For all of you usenet sites that are still running 1200 (or possibly even 300) the modems will pay for themselves very quickly. >From all of the literature that I have recieved here are a few of the advantages of this modem above the others: 1) works at 300 or 1200 or 2400 asyn (others only 1200/2400) 1200 or 2400 sync 2) Stores 10 numbers (40 chars each) (others only 1) 3) For tone dialing it dials ALL 12 (others only can generate tones including (* and #) numbers 0-9) This last one caused a nasty problem when we needed to generate the extra tones because some of the sites we talk to have switching systems that require them (Gandalf). 4) Will automatically change the speed (some of the others needed to the other modem. a manual intervention). --------------- usenet: {philabs, allegra}!sbcs!bruce Bruce Factor Path: ukma!qusavx!hasmed!cbosgd!ihnp4!houxm!vax135!ariel!mdg >From: mdg@ariel.UUCP (M.GALE) Newsgroups: net.micro.cpm Subject: Re: 2400 baud modems Date: Fri, 28-Dec-84 09:20:51 EST Please note at the beginning that this is coming from an account on an AT&T computer. <Reach out and byte someone...> Just wanted to point out that in the recent summeries of modems available people seem to be missing a major manufacturer of modems -- A T & T. Check it out with an A T & T - I S sales rep. They've got 1200/2400 standalone and rackmount systems. And you don't call it the Bell 212 standard for nothing. Please note that I do not work in that department and know only the basics concerning such hardware i.e. it exists. I am not an employee nor an authorized representative of any part of AT&T, I only help solve problems for them on a contract basis. To think that my opinions are those of the company is ludicrous. Michael D. Gale "I just like blinking lights-the DECsystem 10 operator's panel is a work of art" blink-blink-blink-burnout-blink >From rjk@mgweed.UUCP (Randy King) Sun Feb 6 01:28:16 206 Path: ukma!cbosgd!ihnp4!mgnetp!mgweed!rjk Newsgroups: att.general,net.unix Subject: Framing errors and autobaud @ 2400 It seems that autobauding from 1200 down to 300 by means of a framing error is quite reliable when the 300-baud user types almost any character. Hence for years uucp info has contained strings like: login:--login: where the "--" implied "send CR". The reverse did not work, so the 1200-baud user would send a BREAK to upshift the remote to 1200; hence login:-BREAK-login: for the uucp info. Now I am finding that downshifting from 2400 baud to 1200 baud more closely resembles the 300->1200 upshift in that sending a BREAK is the more reliable way. It is not always the case, however. There are times when just a CR from my 1200 baud modem calling a tri-speed modem at 2400 baud will cause the port to fallback to 1200. Many times, however, a BREAK is required to cause the downshift. If you have had experience with 2400 baud autobauding, including upshifts and downshifts among the speeds from 110->2400, I'd like to hear about your findings. This would be important information for future releases of UUCP information from sites with >1200 baud modems. Randy King AT&T-CP@MG ihnp4!mogul!rjk >From W8SDZ@SIMTEL20.ARPA (Keith Petersen) Sun Feb 6 01:28:16 206 Path: ukma!cbosgd!ihnp4!houxm!whuxl!whuxlm!harpo!decvax!genrad!panda!talcott!harvard!seismo!brl-tgr!tgr!W8SDZ@SIMTEL20.ARPA Newsgroups: net.micro Subject: 2400 baud modem review Date: Sun, 31-Mar-85 10:40:40 EST The following review was not written by me. It was downloaded from a Remote CP/M system. Unfortunately there is no way to reach the author because it is unsigned. It is presented here for its possible informational value. Please address discussions/comments to the mailing list, not me. I don't own a 2400 baud modem. --Keith 10 Mar 85 *** DISCLAIMER *** The products described here were repeatedly tested for a specific application only. No value was placed on advanced features not directly related to their intended use. The opinion expressed herein is that of the reviewer and may, in fact WILL differ considerably from other reviewers' opinions. This is an unsolicited review. Anyone able to disprove the reviewes claims is welcome to do so. This review is about as unobjective as it can get. In a data processing environment, chances are the employee with a terminal and a modem (or computer) and access to the business computer via dialup will be more productive and is more likely to put in a few hours' worth of unsolicited overtime per week than the employee who has access to the same computer only during working hours. Therefore, it was decided that the office computer be set up with at least one high-speed dialup line and the most economical choice was that of a 1200/2400 baud modem. The modems were going to be used for two purposes: 1. unattended autoanswer 2. occasional use for dialout Testing was started as soon as modems became available through a local distributor. Due to this factor only two brands were evaluated. Here is the story on both of them: 1. PENRIL 2024 The Penril 2024 seems to be the first widely available 1200/2400 baud modem, with the exception of the prohibitively priced VADIC 4400 series. The 2024's list price is somewhere around $900. The 2024 offers two baud rates, 1200 and 2400. The 1200 baud protocol can be switched from 212A to V.22 at configuration time. By today's standards, the 2024 cannot be considered a "smart" modem in that its smartness is limited to the ability to dial a phone number. Placing the modem in autoanswer mode is accomplished by simply configuring the internal and external switches according to the manual, releasing all front panel switches and plugging it in. The 2024 does not have a power switch (a definite plus in this application). Originating a phone call with the 2024 is a cumbersome procedure, especially in an application where the modem may be 100 feet away from the terminal. First, the modem must be taken out of autoanswer mode by pressing a front panel switch. Next, the originate baud rate must be selected by locking the HI/LO switch IN or OUT. Note that if you set up the modem for 2400 baud, you can call a 1200 baud number because of the "fallback" feature. You just have to adjust your terminal baud rate after connect. The 2024 has no abort provisions. While dialing, the TALK/DATA switch can be used to abort. When connected, you must either cause the remote computer to drop carrier or you again have to hit the switch. An alternative is dropping the DTR line low, but in some instances that's a bit hard to do. Dialing a phone number is very awkward. The sequence is "CRNnnnnnnn<CR><LF>" so to dial 555-1212, you type CRN5551212^M^J. Fine if the ENTER key on your keyboard generates a CR-LF sequence; with most terminals you have to hit two keys. Sorry, no redial capability. The Penril worked fine calling the local TYMNET 2400 baud access number, but no connection was established to any long distance modem at 2400 baud. The modem is superbly suited for unattended autoanswer mode. the 2024 can be turned on and left alone and if something goes wrong it's the software but not the modem. The continuous high-pitched noise coming out of the built-in speaker may be objectionable to some -- it picks up the strongest local AM radio station. the speaker can be turned low or off via an internal jumper block. One 2024 modem was tested initially in early November 1984, and two were again tested in late February 1985. No difference was found between the three modems, even though the early onemay have been a preproduction unit. >From neuro1!sob@rice.ARPA Sun Nov 17 03:22:35 1985 From: Stan Barber <neuro1!sob@neuro1.ARPA> Subject: modems Thought this might be of interest -------- begin included text ---------- Path: neuro1!shell!ut-ngp!ut-sally!seismo!lll-crg!dual!ames!jaw From: jaw@ames.UUCP (James A. Woods) Newsgroups: net.dcom Subject: Paul Baran, modem hero Date: 26 Jul 85 00:55:36 GMT # fools speed ahead that amazing telebit/dca 10kbit modem sure seemed like a minor miracle (infoworld, 7/22), so i called telebit for the technical dope. if the literature is to be believed, bad lines don't really faze the thing. i'm sure a few usenet sites with $2300 would jump for it. is it time to ring the death knell for CCITT modems, which, because of noise and gross fallback strategies, never reach their max throughput? hmm ... "packetized ensemble coding...inventor lists airport metal detector, invention of packet switching in 1964, and co-founding of equatorial communications (your friendly neighborhood spread spectrum service) among his credits". no slouch here. dca stock (telebit is private, but marketer dca is public) has risen to around $30 of late, from about $22 a few weeks back. oh, the dope -- - 512 carrier freqs. each modulated with either 6-bit or 4-bit QAM, or 2-bit QPSK, depending on SNR. - adaptive duplexing, to take advantage of the one-way burst nature of most traffic. - fallback in decrements of < 100 bps. (successive rate halving of the v22 standard is the real killer on dialups.) - bell 103, 212a, and hayes command language compatibility - call (800) telebit ames!jaw Path: neuro1!shell!ut-ngp!ut-sally!seismo!harvard!talcott!panda!genrad!decvax!decwrl!dec-rhea!dec-beta!dieter >From: dieter@beta.DEC Newsgroups: net.dcom Subject: Info on DEC DF224 \"Scholar\" Date: 30 Jul 85 18:52:17 GMT 2400 bps modems - reply >I was wondering about the compatibility of 2400 baud modems. > >ie: > >1) What different types of protocols are there, or aren't there? >2) Specifically, we have a bunch of ATTIS and Concords, which > are compatible, but how compatable are they with DECS new > DF-224s? >3) Which ones perform well, and which ones don't. >4) Is there a prevailing standard, or does it look like there > is going to be one. 1. Most modem vendors offer their own autodial protocol. Lately many have been implementing the Hayes protocol also, in one of two ways. One way is to offer two models, one with Hayes and one with their own. The other is to put the choice in the modem(Penril does this). At Interface many vendors criticized the Hayes protocol but sheepishly admitted that the marketplace demanded it. The DF224 does not support the Hayes protocol, it is unique like the ATTIS and some others. 2. The DF224 was tested with the CDS, Hayes, and Vadic it should be compatible with any other V.22bis modem - especially if it uses the Rockwell chip set (most of the market). 3. Of course the DF224 (Scholar) performs the best! What else could I say... Actually most of the V.22bis modems will be very similar, and we would expect all of the modems made with the Rockwell chips to work the same. 4. I presume the standard referred to is the Autodial method. The perception is that the Hayes autocall method is the most widespread...don't know if its true but it perceived to be so. Mostly due to Smartcomm software making life easy for PC users. The DF224 autocall method is very easy to use and the modem has an extensive menu, 15 stored numbers, redial, nametag calling, etc. I notice that the Hayes 1200 and 2400 versions are different, I wonder how much pain that has caused users wanting to upgrade. The initial question was about compatibility, I think you will find most of the recent V.22bis modems will be very similar. Most will also implement the fall back mode to be Bell 212A compatible rather than V.22. Those that adaptively equalize to the line in 1200 mode will work where a 212 will not. Ralph Dieter DEC Merrimack, NH -- John Quarterman, UUCP: {ihnp4,seismo,harvard,gatech}!ut-sally!im4u!jsq ARPA Internet and CSNET: jsq@im4u.UTEXAS.EDU, formerly jsq@im4u.ARPA
davidsen@steinmetz.UUCP (Davidsen) (12/10/85)
Preliminary testing of the Fastlink (9600+ baud) dialup modems indicates that they do in fact transfer data at about 9600 baud. Because they are half duplex they are no joy at all to use interactively, but a sustained transfer test shows a speed of 925+ cps (10 bit async). The original test was done using two lines on a common PBX. Having done this we switched to a dialout to AT&T and back in. This went from the local PBX to another PBX, to the local Centrex exchange, back to the remote PBX, back to the local PBX. Same result. We then forced a loop out onto out leased (barely) voice grade lines and back. Still okay. The next test will be uucp with the path: local exchange -> longline -> local exchange -> PBX -> PBX. I will report the results of this test in terms of transfer speed as soon as I return (next year). -- billD (..seismo!rochester!steinmetz!crdos1!davidsen) (davidsen@GE-CRD.ARPA) "It seemed like a good idea at the time..."