Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!zaphod.mps.ohio-state.edu!swrinde!ucsd!sdcc6!sdcc6.ucsd.edu!cg108dbd From: cg108dbd@icogsci1.ucsd.edu (Steve -Social Hacker) Newsgroups: comp.dcom.modems Subject: Re: Compucom 9600 baud modems Message-ID: Date: 31 May 91 00:39:37 GMT References: <110.28432781@zswamp.uucp> Sender: news@sdcc6.ucsd.edu Organization: University of California, San Diego -- Cognitive A. I. Lines: 121 In-reply-to: root@zswamp.uucp's message of 28 May 91 14:05:39 GMT Originator: cg108dbd@icogsci6 --=}>> On 28 May 91 14:05:39 GMT, root@zswamp.uucp (Geoffrey Welsh) said: GW> In a letter to All, Adrian Boyko (Adrian_Boyko@resbbs.UUCP ) wrote: [parts deleted..] >A friend of mine said that there was some discussion here >concerning >Compucom's 9600 baud modems. Does this group get archived .. GW> It was a short and relatively calm discussion: GW> GOOD: GW> - It's CHEAP! GW> - They're catching on. GW> - Even if you never connect to another Speedmodem, they're good as a 2400 GW> bps MNP5 modem. Well, I owned one, and I am going to have to disagree with this. I now own a USR HST, and when calling with 2400-MNP5, there is a very noticable difference between a CompuCom and other brands. The CompuCom implementation of MNP5 seems very jerky and filled with (IMHO) overly lengthy pauses. I am familiar with "normal" MNP5 connections, and they are jerky as well, due to the packetting, but much less so. GW> - They claim to use a 16550 UART on their modems, though I don't know if GW> it's the reliable National part or one of the flaky substitutes (WD, MX) GW> - FAX model available From what I was able to tell, they are not using a 16550. I have ran several different UART identifiers, and they all came up with "No 16550". Also, the included MTEZ is supposed to list FIFO in the connection information if a 16550 is detected, and it _does_not_. Again, this is said without any hardware inspection or inside knowledge, but on the software side, I, and all my programs, were unable to find or use a 16550. If anyone knows for sure what is on that card, please post. GW> BAD: GW> - They won't speak 9600 to anything except another Speedmodem GW> - No V.42 GW> - Internal only They have an external model in the making.. Guesstimated release date is approx. late Fall. GW> - They seem to be back-ordered; a friend has had one on order for months GW> - Not full duplex (I suspect half, but asymmetrical has been suggested) According to their documentation, the back-channel is around 350 baud (I can't find the docs now), similar to the HST. GW> - How good can line quality be on a modem whose purpose in life is to do GW> 9600 bps as cheaply as possible? I had no problems with errors on bad lines, but most of my connections are clean. GW> Geoffrey Welsh - Operator, Izot's Swamp BBS (FidoNet 1:221/171) GW> root@zswamp.uucp or ..uunet!watmath!xenitec!zswamp!root One aspect I haven't seen discussed is the actual thoroughput for file transfer. Having owned both the CompuCom and now a USR HST-V.42-14.4K, I was surprised at the dramatic difference. For starters, text reading is MUCH smoother on the HST. The CompuCom exhibits those lengthy packet pauses in 9600 mode as well, and they drive me nuts. As for file xfer, I almost always transfer .ZIP compressed files, so any external protocol they offer (like CCSP) that boasts compression will give me very little, if any. Numbers: On files of medium length (say 250K), clean connections, single-user BBS's, Y-Modem/G HST w/ V.42 at 14.4K: average 1700 cps usually 1620 - 1750 cps I have seen 1750 once or twice 1600 is about the lowest. Most xfers are about 1705-1710 cps. HST without V.42 is less, but I don't have any averages because I do it infrequently. HST at 9600 (old models) is just that, averaging 960 or so cps. (Again, questionable estimate for lack of data.) CompuComm 9600/REL (whatever that means) talking to another of the same on a dedicated BBS: Average 865 cps. usually 850 - 900 cps I did observe 920 once. Speeds as low as 800 - 820 were not uncommon, but less frequent. No, I did not rigorously test over and over on the same files, and this is all just jotting down what the protocol reports as a speed, so it is all very questionable.. BUT for what I do (call BBS's and up&down-load .ZIP files in the 100-300K range) these are very real, and my basis for chosing the HST. Of course, your mileage may, nay *WILL*, vary, so take it all with a grain of statistical salt. I have nothing to do with either CompuCom or USR, etc.. Read my other postings for details on the (excellent) service at CompuCom and other aspects of the modem. Happy Hacking! -Steve -- }>> Steve Haehnichen <<{ shaehnichen@ucsd.edu Disclaimer: UCSD and I do not share any opinions.