Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!casbah.acns.nwu.edu!ftpbox!mothost!motcid!king From: king@motcid.UUCP (Steven King) Newsgroups: comp.sys.amiga.datacomm Subject: Re: Downloading problems !!! Help !!! Keywords: Help Message-ID: <4861@orchid3.UUCP> Date: 20 Mar 91 16:35:08 GMT References: Organization: Motorola Inc. - Cellular Infrastructure Div., Arlington Heights, IL 60004 Lines: 44 In article mac1@ra.MsState.Edu (Cheema) writes: > > I wonder if its only me or everybody else is in the same boat. I have a 1200 >baud modem and when I am downloading some long files say around 400k it makes >me wait for hours (normally 4 to 6 hrs). I have ordered another 2400 baud >modem but still I think I still will have to wait at least a couple of hours >for a file to get downloaded. Is this weird or normal ? > I am currently using Xmodem protocol. Does terminal program has any effect on >this. Also what to do with files that are longer than 880K. i.e they can't be >put onto one diskheema Let's do some ciphering... A good rule of thumb is to figure 10 bits per character, so at 1200 baud you can transfer a max of 120 characters per second. 400K = 409,600 characters, so you can figure the minimum time to transfer is 3413 seconds or .95 hours. Xmodem is a dog (send 128 characters, wait for an ACK, send 128 characters, wait for an ACK...) so I'd double that. I'd expect the transfer to take about 2 hours. Your terminal program *shouldn't* make a difference, but in practice it might. If you've got a poor program it may be wasteing time before it sends the ACK back to the machine you're downloading from. This will add to your overall transfer time. Also, if you've got noisy lines (do you see bursts of garbage when you're logged on?) packets will need to be retransmitted. That will also add to the transfer time. 4 to 6 hours is much longer than expected, but not outside the realm of possibility. If you can, change to Zmodem. Zmodem is a *much* faster protocol because it doesn't send ACKnowledgements back to the host after every so many characters. Instead, it will only send replies to the host during setup and when it detects an error. Also, the CRC error-detection routine Zmodem uses is more sensitive to errors than the checksum routine commonly used by Xmodem. If you've got files longer than 880K and you've only got floppies... Well, you're kind of screwed. If you can, unpack the large file on the host system and download the smaller individual file. If you can't manage that for whatever reason, you're screwed. The only solutions are to buy a hard drive (or one of the new AE high-density floppy drives) or find a friend with one who will transfer it for you. -- ---------------------------------------------------+--------------------------- The amount of work that actually got done during | Steven King the week is inversely proportional to the number | Motorola Cellular of entries in 'timetool'. | ...uunet!motcid!king