kushmer@bnlux0.bnl.gov (christopher kushmerick) (02/01/91)
I am trying to decide if I should spend US$160 for an MNP class 5 modem. I will use it mostly for interactive work over a phone line. I now use a 2400 modem with out MNP, and have okay luck. My line noise is low but not zero (spurious character about 1 in 100 at worst, 1 in 500 at best.) Has anybody recently gone to MNP and able to comment on the speedup I should expect? I expect the modem connection to be the limiting factor (On one end, a 286 running kermit terminal emulator, on the other end, TXA0, a terminal line on the vax.) Thanks in advance -- Chris Kushmerick kciremhsuK sirhC kushmer@bnlux0.bnl.gov <===Try this one first kushmerick@pofvax.sunysb.edu
mlord@bwdls58.bnr.ca (Mark Lord) (02/05/91)
In article <2464@bnlux0.bnl.gov> kushmer@bnlux0.bnl.gov (christopher kushmerick) writes: <I am trying to decide if I should spend US$160 for an MNP class 5 <modem. I will use it mostly for interactive work over a phone line. < <I now use a 2400 modem with out MNP, and have okay luck. My line noise is low <but not zero (spurious character about 1 in 100 at worst, 1 in 500 at best.) < <Has anybody recently gone to MNP and able to comment on the speedup I should <expect? I expect the modem connection to be the limiting factor (On one end, <a 286 running kermit terminal emulator, on the other end, TXA0, a terminal line <on the vax.) Yes, IMHO, it is very much worth it. Almost, but not quite, a 2X speedup when reading news, for example. The higher the volume of text (readable characters), the better the compression and the faster the apparent speedup is. -- ___Mark S. Lord__________________________________________ | ..uunet!bnrgate!mlord%bmerh724 | Climb Free Or Die (NH) | | MLORD@BNR.CA Ottawa, Ontario | Personal views only. | |________________________________|________________________|
kendrix_j@mims.enet.dec.com (John R. Kendrix) (02/06/91)
In article <2464@bnlux0.bnl.gov>, kushmer@bnlux0.bnl.gov (christopher kushmerick) writes... >I am trying to decide if I should spend US$160 for an MNP class 5 >modem. I will use it mostly for interactive work over a phone line. > >I now use a 2400 modem with out MNP, and have okay luck. My line noise is low >but not zero (spurious character about 1 in 100 at worst, 1 in 500 at best.) I use the US Robotics HST with MNP error correction, line noise is practically impossilbe over that modem. That is, IF, you are connected to another modem which uses MNP error correction as well. I've accidently picked up the phone connected to the modem while online, (something which will nearly always kill the connection on a regular modem and definately will display much line noise on the screen), not only did the connection hold, but there was not the first bit of line noise which came through. The most solid connection I've ever seen, barring a data line. >Has anybody recently gone to MNP and able to comment on the speedup I should >expect? I expect the modem connection to be the limiting factor (On one end, >a 286 running kermit terminal emulator, on the other end, TXA0, a terminal line >on the vax.) Your speed up from using MNP will depend on a couple of factors. 1. The type of files that you are transfering. Text file transfers benefit more from MNP 5 than binary. A 19,200 connection MNP 5 transfering a text file will get you from 3500-4000 cps (chars per sec). Binary files, are slower, the transfer rate at 19200 is about 1650 cps. A 2400 baud connection will get you only marginal increase in cps, a non-MNP connection may do 230cps at 2400, while a MNP 5 connection might do as much as 290cps. You should also consider your application, are you going to be transfering alot of big files, or using it as a dumb terminal for the most part. 2400 baud MNP is plenty fast enough to just get a noise free line. If you are going to be transfering large files, you should also think about changing from Kermit to another transfer Protocol. Zmodem, since it doesn't require a reply from the client to send another packet is the best. It uses a larger packet size, as well as a streaming data line. Kermit, must have an ack from the client every 128 bytes to make sure that it got the packet properly. This just slows down data transfers of large files. There are versions of Zmodem in the PD available for the PC as well as the Vax, hope this helps! >Chris Kushmerick kciremhsuK sirhC >kushmer@bnlux0.bnl.gov <===Try this one first >kushmerick@pofvax.sunysb.edu ******************************************************************************** * John R. Kendrix * Disclaimers: The opinions expressed here * * Digital Equipment Corporation * aren't likely to be claimed * * * by me, much less my employer. * * * * * Phone: 404-343-1739 * E-Mail: Kendrix_J@mims.enet.dec.com * ******************************************************************************** * What do I want out of life??? * Just one tiny thing.... MORE!!!!! * ********************************************************************************