waggoner@ichips.intel.com (Mark Waggoner) (05/11/91)
Could someone tell me what the difference between a Supra 2500 MNP
and Supra 2400 MNP plus is?
I'm not fully conversent on protocols, compression schemes and error
correction. My local sysadmin recommends:
2400 baud with V.22bis with MNP2-4 for error correction and MNP-5 for
data compression.
Will I get all of this with the Supra? Any other recommendations?
Thanks
--
Mark Waggoner waggoner@ichips.intel.com (503) 696-4590
No, I don't speak for intel.rockwell@socrates.umd.edu (Raul Rockwell) (05/11/91)
Mark Waggoner:
Could someone tell me what the difference between a Supra 2500 MNP
and Supra 2400 MNP plus is?
the Plus has V.42 and V.42bis (This allows you to use LAPM error
correction (Link Access Procedure M) and BTLZ compression (British
Telecom Lempel-Ziv) in place of MNP -- BTLZ is about twice as fast as
MNP-5, but requires LAPM).
I've never heard of a 2500 :-), but the 2400 MNP is supposed to be
upgradable to a Plus.
My local sysadmin recommends:
2400 baud with V.22bis with MNP2-4 for error correction and
MNP-5 for data compression.
Will I get all of this with the Supra?
yeah.
Btw, I believe all commercial 2400 baud modems are V.22bis.
Raul Rockwellpaul@wa1omm.UUCP (Paul MacDonald) (05/12/91)
In article <ROCKWELL.91May11090125@socrates.umd.edu> rockwell@socrates.umd.edu (Raul Rockwell) writes: >Mark Waggoner: > Could someone tell me what the difference between a Supra 2500 MNP > and Supra 2400 MNP plus is? > >the Plus has V.42 and V.42bis (This allows you to use LAPM error >correction (Link Access Procedure M) and BTLZ compression (British >Telecom Lempel-Ziv) in place of MNP -- BTLZ is about twice as fast as >MNP-5, but requires LAPM). > >I've never heard of a 2500 :-), but the 2400 MNP is supposed to be >upgradable to a Plus. > > > My local sysadmin recommends: > 2400 baud with V.22bis with MNP2-4 for error correction and > MNP-5 for data compression. > Will I get all of this with the Supra? > >yeah. > >Btw, I believe all commercial 2400 baud modems are V.22bis. > >Raul Rockwell I am not aware that the 2400's are upgradeable to a PLUS. According to Supra, they have a swap out program, send in your old Supra 2400 + $129 and they send you a Supra 2400 Plus. Likewise for the 2400zi Plus. The latter won't be available for another couple of weeks. -- 73, Paul _____________________________________________________________________ From the shack of Paul MacDonald! Packet Radio: WA1OMM@KB4N.NH.USA / / /\ / /~~/ /\/\ /\/\ /\ / /\ (~ / / / / /\ /\ / / / \/\/ /~~\ / /__/ / / / / ~ / V /~~\ ) /~/ /_/ /~~\, / V /~/ Internet: ubbs-nh!wa1omm!paul CIS: 70411,626 PLink: UPPERCRUST
nesbbx@agora.UUCP (Bill Seymour) (05/14/91)
In article <1991May10.233030.22425@ichips.intel.com>, Mark Waggoner writes: > Could someone tell me what the difference between a Supra 2500 MNP > and Supra 2400 MNP plus is? The MNP does regular 3/12/2400 baud operation, plus adds MNP levels 2-4 error correction and MNP5 data compression. When connected with another MNP compatible modem, you should see an improvement in error handling and an improvement is uncomressed data speed. The theoretical limit to the higher throughput is 4800 baud, or a 2:1 ratio. In the real world, expect to see about 3000 baud for text and something less than 2400 baud for compressed data. The Plus modem has everything the MNP does, plus V.42 error correction and V.42bis data compression. Both V.42 and V.42bis are more advanced techniques than the older MNP stuff. V.42bis gives a maximum compression ratio of 4:1, making 9600 baud theoretically possible. But there's a difference on precompressed files... With MNP5, you get an actual *slowdown* on precompressed files, since it doesn't know enough to shut itself off, with V.42bis, the compression algorythm shuts itself down on compressed files yet still gives you the advantage of the psuedosyncronous transmission (start and stop bits are stripped, giving a 20% speed increase) Because of this, you should see data rates of about 5000 bps with text and 2800 bps on compressed files. > I'm not fully conversent on protocols, compression schemes and error > correction. My local sysadmin recommends: > 2400 baud with V.22bis with MNP2-4 for error correction and MNP-5 for > data compression. You'll get that with either modem, although if you're transfering compressed files, you'll want to disable the MNP5. > Will I get all of this with the Supra? Any other recommendations? > > Thanks > > -- > Mark Waggoner waggoner@ichips.intel.com (503) 696-4590 > No, I don't speak for intel. Bill Seymour (Is this really getting out beyond my machine?) -Bill Seymour nesbbx!billsey@agora.uucp or nesbbx!billsey@agora.rain.com ***** American People/Link Amiga Zone Hardware Specialist NES*BILL ***** Bejed, Inc. NES, Inc. NAG BBS NES BBX BBS Home Sometimes (503)281-8153 (503)246-9311 (503)656-7393 (503)640-9337 (503) 640-0842
Reid_Bishop@a68k.UUCP (Reid Bishop) (05/17/91)
In a message dated Fri 17 May 91 05:50, Billsey!nesbbx@agora.uucp (bill Sey wrote: BS> But there's a difference on precompressed files... With MNP5, you get an BS> actual *slowdown* on BS> precompressed files, since it doesn't know enough to shut itself off I disagree here. In theory, this _should_ be true, but tests I have conducted prove just the opposite. My BBS has MNP-5 modems on all lines, and tests show that file transfers of compressed files (typically LHArced files...) are _always_ faster using MNP-5 than not. My BBS is locked at 9600 baud regardless of the connect rate, so BBS output is always constant. If I call my BBS with straight 2400 baud, I get around 240 CPS under ideal conditions. If I call using MNP-5, I get closer to 250-260 CPS, and sometimes better when downloading LHarced files. In addition, I used to run a straight 2400 baud modem on the FIDO line, and transfers never went over 240 CPS. Now, they go well over 250 CPS, again these files are LHarced. These transfers are with a USR DS modem on the other end. In a sense, MNP5 _can_ and _does_ improve transfer rates on compressed files. BS> You'll get that with either modem, although if you're transfering BS> compressed files, you'll want to disable the MNP5. I would run tests before actually disabling MNP5. -- Via DLG Pro v0.97b ~~~~~~~~~~~~~ Somebody's gotta fight for the AMIGA!! ~~~~~~~~~~~~~~~~~ Reid Bishop- Customer Support & Programming, M.V. Micro UUCP: boulder!tcr!a68k!Reid_Bishop [Reid Bishop] FIDO: (1:104/224) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ewaniu@ee.ualberta.ca (Darren Ewaniuk) (05/20/91)
In article <Reid_Bishop.3216@a68k.UUCP> Reid_Bishop@a68k.UUCP (Reid Bishop) writes: >In a message dated Fri 17 May 91 05:50, Billsey!nesbbx@agora.uucp (bill Sey >wrote: > BS> But there's a difference on precompressed files... With MNP5, you get an BS> actual *slowdown* on BS> precompressed files, since it doesn't know enough to shut itself off > >I disagree here. In theory, this _should_ be true, but tests I have >conducted prove just the opposite. My BBS has MNP-5 modems on all lines, and >tests show that file transfers of compressed files (typically LHArced >files...) are _always_ faster using MNP-5 than not. My BBS is locked at 9600 >baud regardless of the connect rate, so BBS output is always constant. If I >call my BBS with straight 2400 baud, I get around 240 CPS under ideal >conditions. If I call using MNP-5, I get closer to 250-260 CPS, and >sometimes better when downloading LHarced files. > >In addition, I used to run a straight 2400 baud modem on the FIDO line, and >transfers never went over 240 CPS. Now, they go well over 250 CPS, again >these files are LHarced. These transfers are with a USR DS modem on the >other end. > >In a sense, MNP5 _can_ and _does_ improve transfer rates on compressed files. Yes, compared to straight 2400, but not as much as turning compression off but leaving MNP4 active (see below). BS> You'll get that with either modem, although if you're transfering BS> compressed files, you'll want to disable the MNP5. > >I would run tests before actually disabling MNP5 Turn off compression only, and you'll see the difference. MNP4 increases throughput of a 2400 Supramodem Plus to about 272 CPS. This is due to the stripping of start/stop bits, and transmitting everything in packets. However, MNP5 compression DOES expand archived files. The net result is that archived files have a lower throughput for MNP5 as opposed to MNP4. MNP5 rates are close to the 250 CPS or so that you stated above. Compared to MNP4 (272 CPS) it is slower. However, you do gain a bit over straight 2400 baud files (232 CPS) because of the MNP4 packetizing that is part of MNP5. But, since all MNP5 modems also do MNP4, to get maximum throughput, you will want to turn MNP5 data compression off to use MNP4. With the Supramodem Plus (or MNP), you can do this with the AT command %C0. This can be in your startup string, or you can place it in your dial command string after the AT and before the D###-####. If you are using the excellent JR-Comm telecommunications package, then you can put this in the modem parameters' alternate dial prefixes and then select this alternate prefix, so that this will be used only for the boards that you download archived files from. Since you run a bulletin board, I would suggest that you disable compression in dial-out mode only, and put this in your dial command string rather than the modem setup string, then tell your users how to disable compression on their systems for file transfer. This will then enable them to use compression when they log on to read messages, and by disabling compression from their end, they could increase throughput when they know they are going to download archived files. However, V.42 modems are a lot simpler, since you just don't have to worry about compression or not, because it will never decrease throughput like MNP5 does. That all said, I'd like to add my three months' experience with my Supramodem Plus to the original purpose of this thread. First, I would probably recommend against the average person upgrading to a MNP/V42 modem if you already have 2400 baud. You don't get much extra for throughput. I've never seen the Supramodem Plus go above about 520 CPS for text, and about the maximum for archived files is 272 CPS. All you gain is about 40 CPS over a normal 2400 baud modem. Bulletin board sysops could use the extra speed a bit more, but most already use the 9600+ baud modems. For the new modem user, or for those upgrading from slow 300 or 1200 baud modems, MNP or V42 could be useful. If you intend on a lot of text reading it proves useful (and since this is usenet, most of you do a lot of text reading!). If you intend to mainly download, only go MNP or V42 if you want to spend the extra money, as there won't be much gain. Finally, If you do decide to go for an error correcting modem, I'd probably recommend the V42 one, (a Supramodem Plus over a Supramodem MNP), as it is faster for text and does not decrease throughput in compression mode. (eliminating the need to disable compression while downloading) One final note: MNP and V42 are quite well supported for dialing into local bulletin board systems. All USRobotics modems that I know of support at least MNP4, with about half supporting MNP5/V42. Most other 9600 baud systems also support at least MNP4. However, there are some boards that are just plain 2400, and no modem will increase this speed. Before buying that MNP or V42 modem, be sure that the main systems that you will use will support it. I hope this helps. -- // AMIGA Darren Ewaniuk Graduating student of \\ // the power ewaniu@bode.ee.ualberta.ca University of Alberta \X/ is yours! Proud Amiga 2000 owner Electrical Engineering program
holgerl@amiux.agsc.sub.org (Holger Lubitz) (05/21/91)
In article <Reid_Bishop.3216@a68k.UUCP> Reid_Bishop@a68k.UUCP (Reid Bishop) writes: >In a sense, MNP5 _can_ and _does_ improve transfer rates on compressed files. No, it _can't_ and _doesn't_ improve transfer rates on compressed files. The common misunderstanding about MNP5 is that when you're running MNP5 you are ONLY running MNP5. In fact, you're running MNP5 *upon* another Class of MNP, usually MNP4. >I would run tests before actually disabling MNP5. And tests show that downloading compressed files with MNP4+MNP5 is slower than downloading with MNP4 only. Best regards, Holger -- Holger Lubitz, Kl. Drakenburger Str. 24, D-W-3070 Nienburg/Weser
Reid_Bishop@a68k.UUCP (Reid Bishop) (05/30/91)
In a message dated Tue 21 May 91 19:25, Ewaniu@ee.ualberta.ca (darren Ewani wrote: RB> In a sense, MNP5 _can_ and _does_ improve transfer rates on compressed RB> files. EE> Yes, compared to straight 2400, but not as much as turning EE> compression off EE> but leaving MNP4 active (see below). EE> Turn off compression only, and you'll see the difference. I hadn't thought about the difference between MNP4 and MNP5. I will have to try your suggestion out and see what difference it makes. EE> Since you run a bulletin board, I would suggest that you disable EE> compression EE> in dial-out mode only, and put this in your dial command string EE> rather than the EE> modem setup string, then tell your users how to disable compression EE> on their EE> systems for file transfer. This will then enable them to use EE> compression when EE> they log on to read messages, and by disabling compression from their EE> end, EE> they could increase throughput when they know they are going to EE> download EE> archived files. Very good suggestion. Time to run some tests! (Of course, I fully intend to graduate to USR DS modems in the near future.) Along these lines... do the newer DS modems from USR also implement v.42? I know their straight v.32 modems (non-HST) are now v.42, but I have not seen any advertisements indicating the DS modems including v.42/v.42bis. EE> First, I would probably recommend against the average person EE> upgrading to a EE> MNP/V42 modem if you already have 2400 baud. You don't get much EE> extra for EE> throughput. What about the user experiencing line noise on a constant basis? Here the investment in any MNP modem will be a plus. -- Via DLG Pro v0.97b ~~~~~~~~~~~~~ Somebody's gotta fight for the AMIGA!! ~~~~~~~~~~~~~~~~~ Reid Bishop- Customer Support & Programming, M.V. Micro UUCP: boulder!tcr!a68k!Reid_Bishop [Reid Bishop] FIDO: (1:104/224) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~